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The red-winged blackbird (''Agelaius phoeniceus'') is a
passerine A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by t ...
bird of the family Icteridae found in most of North America and much of Central America. It breeds from
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...
and
Newfoundland Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...
south to Florida, the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...
, Mexico, and Guatemala, with isolated populations in western El Salvador, northwestern Honduras, and northwestern Costa Rica. It may winter as far north as
Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...
and
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
, but northern populations are generally migratory, moving south to Mexico and the southern United States. Claims have been made that it is the most abundant living land bird in North America, as bird-counting censuses of wintering red-winged blackbirds sometimes show that loose flocks can number in excess of a million birds per flock and the full number of breeding pairs across North and Central America may exceed 250 million in peak years. It also ranks among the best-studied wild bird species in the world. The red-winged blackbird is
sexually dimorphic Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
; the male is all black with a red shoulder and yellow wing bar, while the female is a nondescript dark brown. Seeds and insects make up the bulk of the red-winged blackbird's diet.


Taxonomy

The red-winged blackbird is one of five species in the
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''
Agelaius ''Agelaius'' is a genus of blackbirds in the New World family Icteridae. Established by Louis Jean Pierre Vieillot in 1816, it contains five species: The name ''Agelaius'' comes from the Greek ', meaning "gregarious". Gallery File:Blackbird t ...
'' and is included in the family
Icteridae Icterids () or New World blackbirds make up a family, the Icteridae (), of small to medium-sized, often colorful, New World passerine birds. Most species have black as a predominant plumage color, often enlivened by yellow, orange, or red. Th ...
, which is made up of
passerine A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by t ...
birds found in
North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...
and South America. The red-winged blackbird was formally described as ''Oriolus phoeniceus'' by
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
in 1766 in the twelfth edition of his ''
Systema Naturae ' (originally in Latin written ' with the ligature æ) is one of the major works of the Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the system, now known as binomial nomen ...
'', but was later moved with the other American blackbirds to the genus ''Agelaius'' by
Louis Jean Pierre Vieillot Louis Pierre Vieillot (10 May 1748, Yvetot – 24 August 1830, Sotteville-lès-Rouen) was a French ornithologist. Vieillot is the author of the first scientific descriptions and Linnaean names of a number of birds, including species he collecte ...
in 1816. Linnaeus specified the type location as "America" but this was restricted to
Charleston, South Carolina Charleston is the largest city in the U.S. state of South Carolina, the county seat of Charleston County, and the principal city in the Charleston–North Charleston metropolitan area. The city lies just south of the geographical midpoint o ...
in 1928. The genus name is derived from
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
, meaning "gregarious". The specific epithet, , is
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
meaning "crimson" or "red". The red-winged blackbird is a
sister species In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...
to the
red-shouldered blackbird The red-shouldered blackbird (''Agelaius assimilis'') is a species of bird in the family Icteridae. It is endemic to Cuba, but despite its limited range, the species is listed as Least Concern on the IUCN Red List The International Union for ...
(''Agelaius assimilis'') that is
endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
to
Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...
. These two species are together sister to the
tricolored blackbird The tricolored blackbird (''Agelaius tricolor'') is a passerine bird of the family Icteridae. Its range is limited to the coastal areas of the Pacific Ocean, Pacific coast of North America, from Northern California in the U.S. (with occasional st ...
(''Agelaius tricolor'') that is found on the Pacific coast region of the California and upper
Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...
in Mexico. Depending on the authority, between 20 and 24 subspecies are recognised which are mostly quite similar in appearance. However, there are two isolated populations of bicolored blackbirds that are quite distinctive: ''A. p. californicus'' of California and ''A. p. gubernator'' of central Mexico. The taxonomy and relationships between these two populations and with red-winged blackbirds is still unclear. Despite the similarities in most forms of the red-winged blackbird, in the subspecies of
Mexican Plateau The Central Mexican Plateau, also known as the Mexican Altiplano ( es, Altiplanicie Mexicana), is a large arid-to-semiarid plateau that occupies much of northern and central Mexico. Averaging above sea level, it extends from the US-Mexico border ...
, ''A. p. gubernator'', the female's veining is greatly reduced and restricted to the throat; the rest of the plumage is very dark brown, and also in a different family from the European
redwing The redwing (''Turdus iliacus'') is a bird in the thrush family, Turdidae, native to Europe and the Palearctic, slightly smaller than the related song thrush. Taxonomy and systematics This species was first described by Carl Linnaeus in h ...
and the Old World
common blackbird The common blackbird (''Turdus merula'') is a species of true thrush. It is also called the Eurasian blackbird (especially in North America, to distinguish it from the unrelated New World blackbirds), or simply the blackbird where this does not ...
, which are
thrushes The thrushes are a passerine bird family, Turdidae, with a worldwide distribution. The family was once much larger before biologists reclassified the former subfamily Saxicolinae, which includes the chats and European robins, as Old World flyca ...
(Turdidae). In the California subspecies, ''A. p. californicus'' and ''A. p. mailliardorum'', the veining of the female specimens also covers a smaller surface and the plumage is dark brown, although not in the ''gubernator'' grade; and also its superciliary list is absent or poorly developed. The male subspecies ''mailliardorum'', ''californicus'', ''aciculatus'', ''neutralis'', and ''gubernator'' lack the yellow band on the wing that is present in most male members of the other subspecies. The red-shouldered blackbird was formerly considered as a subspecies of red-winged blackbird. They were split by the
American Ornithologists' Union The American Ornithological Society (AOS) is an ornithological organization based in the United States. The society was formed in October 2016 by the merger of the American Ornithologists' Union (AOU) and the Cooper Ornithological Society. Its m ...
in 1997. Listed below are the red-winged blackbird subspecies and groups of subspecies recognized as of January 2014 with their respective distribution areas and the location of their wintering quarters: * Group phoeniceus: ** ''A. p. arctolegus'' – from southeastern
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...
and
Yukon Yukon (; ; formerly called Yukon Territory and also referred to as the Yukon) is the smallest and westernmost of Canada's three territories. It also is the second-least populated province or territory in Canada, with a population of 43,964 as ...
to the north-central United States; migrates to the south-central United States. ** ''A. p. fortis'' – from
Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columbi ...
to southeastern
New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...
(east of the
Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico in ...
); migrates to
Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...
. ** ''A. p. nevadensis'' – from southeastern
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
to
Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyom ...
, southeastern California, and southern
Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
; migrates to southern
Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
. ** ''A. p. caurinus'' – from the southwest coast of British Columbia to northwest California; migrates to central California. ** ''A. p. aciculatus'' – mountains of central-southern California (central-eastern
Kern County Kern County is a county located in the U.S. state of California. As of the 2020 census, the population was 909,235. Its county seat is Bakersfield. Kern County comprises the Bakersfield, California, Metropolitan statistical area. The county sp ...
). ** ''A. p. neutralis'' – from the coast of southern California (
San Luis Obispo County San Luis Obispo County (), officially the County of San Luis Obispo, is a county on the Central Coast of California. As of the 2020 census, the population was 282,424. The county seat is San Luis Obispo. Junípero Serra founded the Miss ...
) to the northwest of Baja California. ** ''A. p. sonoriensis'' – from southeastern California to northeast
Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...
, southern Nevada, central Arizona, and northwest Mexico. ** ''A. p. nyaritensis'' – coastal plains of southwestern Mexico (
Nayarit Nayarit (), officially the Free and Sovereign State of Nayarit ( es, Estado Libre y Soberano de Nayarit), is one of the 31 states that, along with Mexico City, comprise the Federal Entities of Mexico. It is divided in 20 municipalities and its ...
). ** ''A. p. grinnelli'' – Pacific Slope from western Guatemala to northwest Costa Rica ( Guanacaste). ** ''A. p. phoeniceus'' – from southeastern Canada to Texas and the southeastern United States. ** ''A. p. littoralis'' –
Gulf Coast The Gulf Coast of the United States, also known as the Gulf South, is the coastline along the Southern United States where they meet the Gulf of Mexico. The coastal states that have a shoreline on the Gulf of Mexico are Texas, Louisiana, Mississ ...
from Southeast Texas to Northwest Florida. ** ''A. p. mearnsi'' – extreme southeast
Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to the ...
and northern Florida. ** ''A. p. floridanus'' – South Florida (
Everglades The Everglades is a natural region of tropical climate, tropical wetlands in the southern portion of the U.S. state of Florida, comprising the southern half of a large drainage basin within the Neotropical realm. The system begins near Orland ...
to
Key West Key West ( es, Cayo Hueso) is an island in the Straits of Florida, within the U.S. state of Florida. Together with all or parts of the separate islands of Dredgers Key, Fleming Key, Sunset Key, and the northern part of Stock Island, it cons ...
). ** ''A. p. megapotamus'' – from central Texas and the lower Rio Bravo valley to eastern Mexico (northern
Veracruz Veracruz (), formally Veracruz de Ignacio de la Llave (), officially the Free and Sovereign State of Veracruz de Ignacio de la Llave ( es, Estado Libre y Soberano de Veracruz de Ignacio de la Llave), is one of the 31 states which, along with Me ...
). ** ''A. p. richmondi'' –
Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...
slope from Mexico (southern Veracruz) to
Belize Belize (; bzj, Bileez) is a Caribbean and Central American country on the northeastern coast of Central America. It is bordered by Mexico to the north, the Caribbean Sea to the east, and Guatemala to the west and south. It also shares a wate ...
and northern Guatemala. ** ''A. p. pallidulus'' – southeast Mexico (north of the Yucatan peninsula). ** ''A. p. nelsoni'' – south-central Mexico (from
Morelos Morelos (), officially the Free and Sovereign State of Morelos ( es, Estado Libre y Soberano de Morelos), is one of the 32 states which comprise the Federal Entities of Mexico. It is divided into 36 municipalities and its capital city is Cuer ...
and the adjacent
Guerrero Guerrero is one of the 32 states that comprise the 32 Federal Entities of Mexico. It is divided in 81 municipalities and its capital city is Chilpancingo and its largest city is Acapulcocopied from article, GuerreroAs of 2020, Guerrero the pop ...
west of
Puebla Puebla ( en, colony, settlement), officially Free and Sovereign State of Puebla ( es, Estado Libre y Soberano de Puebla), is one of the 32 states which comprise the Federal Entities of Mexico. It is divided into 217 municipalities and its cap ...
and
Chiapas Chiapas (; Tzotzil language, Tzotzil and Tzeltal language, Tzeltal: ''Chyapas'' ), officially the Free and Sovereign State of Chiapas ( es, Estado Libre y Soberano de Chiapas), is one of the states that make up the Political divisions of Mexico, ...
). ** ''A. p. matudae'' – tropical southeast Mexico (not always recognised). ** ''A. p. arthuralleni'' – northern Guatemala. ** ''A. p. brevirostris'' – Caribbean slope of
Honduras Honduras, officially the Republic of Honduras, is a country in Central America. The republic of Honduras is bordered to the west by Guatemala, to the southwest by El Salvador, to the southeast by Nicaragua, to the south by the Pacific Oce ...
and southeastern
Nicaragua Nicaragua (; ), officially the Republic of Nicaragua (), is the largest country in Central America, bordered by Honduras to the north, the Caribbean to the east, Costa Rica to the south, and the Pacific Ocean to the west. Managua is the cou ...
(sometimes included in ''richmondi''). ** ''A. p. bryanti'' – northwest
Bahamas The Bahamas (), officially the Commonwealth of The Bahamas, is an island country within the Lucayan Archipelago of the West Indies in the Atlantic Ocean, North Atlantic. It takes up 97% of the Lucayan Archipelago's land area and is home to ...
. * Group californicus/ mailliardorum: ** ''A. p. mailliardorum'' – Central California Coast. ** ''A. p. californicus'' –
Central Valley of California The Central Valley is a broad, elongated, flat valley that dominates the interior of California. It is wide and runs approximately from north-northwest to south-southeast, inland from and parallel to the Pacific coast of the state. It covers ...
. * Group gubernator : ** ''A. p. gubernator'' –
Mexican Plateau The Central Mexican Plateau, also known as the Mexican Altiplano ( es, Altiplanicie Mexicana), is a large arid-to-semiarid plateau that occupies much of northern and central Mexico. Averaging above sea level, it extends from the US-Mexico border ...
(
Durango Durango (), officially named Estado Libre y Soberano de Durango ( en, Free and Sovereign State of Durango; Tepehuán: ''Korian''; Nahuatl: ''Tepēhuahcān''), is one of the 31 states which make up the 32 Federal Entities of Mexico, situated in ...
to
Zacatecas , image_map = Zacatecas in Mexico (location map scheme).svg , map_caption = State of Zacatecas within Mexico , coordinates = , coor_pinpoint = , coordinates_footnotes = , subdivision_type ...
, Mexico and
Tlaxcala Tlaxcala (; , ; from nah, Tlaxcallān ), officially the Free and Sovereign State of Tlaxcala ( es, Estado Libre y Soberano de Tlaxcala), is one of the 32 states which comprise the Federal Entities of Mexico. It is divided into 60 municipaliti ...
).


Description

The common name for the red-winged blackbird is taken from the mainly black adult male's distinctive red shoulder patches, or ''epaulets'', which are visible when the bird is flying or displaying. At rest, the male also shows a pale yellow wingbar. The spots of males less than one year old, generally subordinate, are smaller and more orange than those of adults. The female is blackish-brown and paler below. The female is smaller than the male, at long and weighing , against his length of and weight of . The smallest females may weigh as little as whereas the largest males can weigh up to . Each wing can range from , the tail measures , the culmen measures and the tarsus measures . The upper parts of the female are brown, while the lower parts are covered by an intense white and dark veining; also presents a whitish superciliary list. Females exhibit a year or salmon pink stain on the shoulders and a clear pink color on the face and below this, while older show a stain usually more crimson on the shoulders and dark pink hue on and under the face. Observations in females in captivity indicate that small amounts of yellow pigment are present on the shoulders of these after leaving the
nest A nest is a structure built for certain animals to hold eggs or young. Although nests are most closely associated with birds, members of all classes of vertebrates and some invertebrates construct nests. They may be composed of organic materia ...
, that the concentration of the pigment increases with the first winter plumage after the change of the feathers and that the passage from yellow to orange generally takes place in the second summer with the acquisition of the second winter plumage, after which no further changes in feather color occur. The colored area on the wing increases in surface with the age of the female, and varies in intensity from brown to a bright red-orange similar to that of the males in their first year. Young birds resemble the female, but are paler below and have buff feather fringes. Both sexes have a sharply pointed bill. The tail is of medium length and is rounded. The eyes, bill, and feet are all black. Unlike most North American passerines which develop their adult plumage in their first year of life so that the one-year-old and the oldest individual are indistinguishable in the breeding season, the red-winged blackbird does not. It acquires its adult plumage only after the breeding season of the year following its birth when it is between thirteen and fifteen months of age. Young males go through a transition stage in which the wing spots have an orange coloration before acquiring the most intense tone typical of adults. The male measures between in length, while the female measures . Its wingspan is between approximately. Both the peak male and the legs, the claws and the eyes are black; in the female beak is dark brown and clear in the upper half at the bottom, and the tail is medium in length and rounded. As in other species
polygyny Polygyny (; from Neoclassical Greek πολυγυνία (); ) is the most common and accepted form of polygamy around the world, entailing the marriage of a man with several women. Incidence Polygyny is more widespread in Africa than in any o ...
exists, the red-winged blackbird exhibit considerable
sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
both in plumage and size, males weighing between 65 and 80g the females about 35g. Males are 50% heavier than females, 20% larger in its linear dimensions, and 20% larger compared to the length of their wings. The trend towards greater dimorphism in the size of non-
monogamous Monogamy ( ) is a form of Dyad (sociology), dyadic Intimate relationship, relationship in which an individual has only one Significant other, partner during their lifetime. Alternately, only one partner at any one time (Monogamy#Serial monogamy, ...
ichterid species indicates that the larger size of males has evolved due to
sexual selection Sexual selection is a mode of natural selection in which members of one biological sex mate choice, choose mates of the other sex to mating, mate with (intersexual selection), and compete with members of the same sex for access to members of t ...
. The male is unmistakable except in the far west of the US, where the
tricolored blackbird The tricolored blackbird (''Agelaius tricolor'') is a passerine bird of the family Icteridae. Its range is limited to the coastal areas of the Pacific Ocean, Pacific coast of North America, from Northern California in the U.S. (with occasional st ...
occurs. Males of that species have a darker red epaulet edged with white, not yellow. Females of tricolored, bicolored, red-shouldered and red-winged blackbirds can be difficult to identify in areas where more than one form occurs. In flight, when the field marks are not easily seen, the red-winged blackbird can be distinguished from less closely related icterids such as
common grackle The common grackle (''Quiscalus quiscula'') is a species of large icterid bird found in large numbers through much of North America. First described in 1758 by Carl Linnaeus, the common grackle has three subspecies. Adult common grackles have a ...
and
brown-headed cowbird The brown-headed cowbird (''Molothrus ater'') is a small, obligate brood parasitic icterid native to temperate and subtropical North America. It is a permanent resident in the southern parts of its range; northern birds migrate to the southern ...
by its different silhouette and undulating flight.


Staining of red spots and yellow bands

Two keto-carotenoids – carotenoid with a
ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...
group – reds synthesized by the birds themselves – namely
astaxanthin Astaxanthin is a keto- carotenoid within a group of chemical compounds known as terpenes. Astaxanthin is a metabolite of zeaxanthin and canthaxanthin, containing both hydroxyl and ketone functional groups. It is a lipid-soluble pigment with r ...
and canthaxanthin – are responsible for the bright red color of the wing spots, but two yellow dietary precursor pigments –
lutein Lutein (;"Lutein"
zeaxanthin Zeaxanthin is one of the most common carotenoids in nature, and is used in the xanthophyll cycle. Synthesized in plants and some micro-organisms, it is the pigment that gives paprika (made from bell peppers), corn, saffron, goji ( wolfberries), ...
– are also present in moderately high concentrations in red feathers. Astaxanthin is the carotenoid more abundant (35% of the total), followed by lutein (28%), canthaxanthin (23%) and zeaxanthin (12%). Such a balanced combination of dietary precursors and metabolic derivatives in colored feathers is quite unusual, not only within a species as a whole but also in individuals and particular feathers. After removing the carotenoids in an experiment, the red feathers acquired a deep brown coloration. This is because the feather barbles of the colored spot contain
melanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino ...
pigments – mainly eumelanin, which was equivalent to 83% of all melanins, but also pheomelanin at a concentration approximately equal to that of carotenoids, which seems to be a rare trait for carotenoid-based ornamental plumage. On the other hand, the feathers of the yellow stripes of the males are devoid of carotenoids —except occasionally when they appear tinged with a pink coloration derived from small amounts of said pigments— and present high concentrations of pheomelanin —82% of all melanins. Melanin concentrations in the yellow band are even higher than in the red spot.


Role of wing spots

These markings are vital in the defense of the
territory A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or a ...
. Males with larger spots are more effective at chasing away their non-territorial rivals and are more successful in contests within aviaries. When the red shoulder patches were dyed black as part of an experiment, 64% of males lost their territories, while only 8% of control subjects did. However, males whose wings had been dyed before they had mated could still attract females and successfully reproduce. In the red-winged blackbird, the spots on the wings are a sign of threat among males and have an unimportant role, if any, in intersex encounters. Therefore, the spots are likely to have evolved in response to pressures linked to intrasexual selection. Additionally, neither the size nor the coloration of the same are linked to the reproductive success of the males with those females that are not their mates, that is, those with which they eventually mate. It has been suggested that also in the case of females, the best explanation for the evolution of a variable coloration in the shoulder spots is that their intensity indicates their physical condition in aggressive encounters between them. The fact that female red-winged blackbirds do not appear to consistently use variability in the size and color of male wing spots when choosing a mate runs counter to the classic role of carotenoid pigmentation ornamental feathers, mostly used in the attraction of a couple. In turn, its use as a sign of aggressiveness and social status against rival males is not a common trait in carotenoid ornaments. On the other hand, ornaments with a preponderance of melanin do tend to have an important role as an indicator of status in avian populations, so the spots of red-winged blackbirds seem to work more as melanin ornaments than as carotenoids.


Vocalizations

The calls of the red-winged blackbird are a throaty ''check'' and a high slurred whistle, '. The male's song, accompanied by a display of his red shoulder patches, is a scratchy ', except that in many western birds, including bicolored blackbirds, it is '. The female also sings, typically a scolding chatter '.


Feather molt

The most critical period of feather molting runs from late August to early September. When viewed in flight, they have a misaligned or "moth-eaten" appearance and generally slower and more laborious travel. Their mobility is reduced due to the lack of several
remiges Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tail ...
or
rectrices Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tail ...
or these are not entirely renewed. Most of the red-winged blackbirds have moved almost entirely by October. By then, some birds have not completed the molt of the feathers of the capital region and the helmsmen of the center of the tail and the internal secondary sprouts have only partially emerged from the pod. Virtually all individuals have completed their molts by mid-October. Birds do not begin their migration to wintering quarters until the two outer primary sprouts and the two inner or central rectrices have completed at least two-thirds of their development. Therefore, there is a correlation between molting, particularly replacement of the remiges and rectrices, and fall migration in red-winged blackbirds.


Succession of plumages and molts

* Juvenile plumage: in both males and females, juvenile plumage is similar in color and pattern to that of the adult female, except for the yellow coloration of the lower body and the sides of the head . The shoulder spots appear mottled and are brown and yellow or brown and beige. Other sources describe the juvenile plumage of the male as follows: above, including the sides of the head, the wings, the tail and the lesser coverts – the feathers of the "shoulders" -, dull brownish black – not seen no red at this stage—, with beige-bordered feathers, paler and narrower in primaries, rectrices, head, and bladderand deeper in the scapulars and secondaries; below, pinkish beige, ocher above chin, densely veined — except chin — with brownish black stripes; undefined ocher-beige superciliary list. The female is described as more brown above with less beige below and a closely veined chin. * First pre-basic molt (or post-juvenile molt): Generally begins 45–60 days after individuals have left the nest. The molt begins in August and the time at which it begins varies between early and late clutches. This is a complete molt, except for the retention in some individuals of a few down feathers under the wing. * Appearance in autumn and winter of the first basic plumage (also called the first winter plumage or immature plumage): in the male, it is black, with the feathers of the upper part bordered with brown or beige and those of the lower part bordered with beige or white. The bird then has a mottled appearance. The shoulder spot is generally orange with black speckles, especially on the yellow stripe. Some immature males have a reddish patch like adults, but with black specks on the yellow band. Others have a blackish spot on the shoulder. Other sources describe the male's first winter plumage as follows: all plumage, including wings and tail, greenish-black, much of it with beige and rust edges, paler underneath and faint or absent in primaries and rectrices; minor wing covers – "shoulders" – orpiment-dull orange, each feather with black subterminal bars or spots; medium beige, deep ocher coverts, generally mottled with black in subterminal areas, mainly in the beards of the inner part of the feathers; generally black spines. :Females are dark above with feathers bordered with beige or rust. The lower part shows black and white streaks, but with more beige on the chest and sometimes on the flanks than in the reproductive plumage. The medium and secondary major cover feathers are noticeably bordered with beige. They generally lack the pink coloration on the chin and throat – which may be beige, yellow, or light salmon – and the crimson wing patch – which may be rust, orange, or gray – typical of second winter plumage. * Appearance in spring and summer of the first basic plumage (also known as the first breeding plumage or sub-adult plumage): the males, which normally are not yet defending a territory, present a dull black coloration acquired by the wear of the edges of the feathers. The stain alar may be more noticeable than in the first winter plumage due to wear subterminal blacklists, which generally only remain in the form of small black spots. Mottled wing spots are characteristic of young individuals and the extent of orange is highly variable. Females, which are usually already breeding, exhibit plumage similar to the first winter plumage, but darker above due to wear on beige edges or rust on feathers. The chest is less beige, and has a black and white veining. * Second and subsequent prebasic molts (or postnuptial molts) : the second prebasic molt takes place approximately one year after the first. Postnuptial molts constitute complete molts, except for the occasional retention of a few down feathers under the wing. * Appearance in autumn and winter of the second and subsequent basic plumages (also called adult winter plumage or second winter plumage) : the male no longer exhibits the mottled appearance characteristic of the autumn and winter appearance of the first basic plumage. The lower part is almost immaculate and similar to that of the reproductive plumage. The head and back feathers and the secondary covers are bordered with brown and beige. The wing blot becomes bright scarlet-vermilion, while deep ocher beige coloration appears on the medium coats. Other sources describe the adult winter plumage of the male as follows: glossy greenish black; feathers of the head, back, major wing covers and tertiary more or less bordered, depending on the individual, beige and rust; below, paler or absent edges. The female's plumage is similar to the autumn and winter appearance of the first basic plumage, except that the wing spot is generally crimson and the chin and throat pink. * Aspect in summer and spring of the second and subsequent basic plumages (or adult bridal plumage): it is acquired through the wear of the feathers. is similar to the appearance in the spring and summer of the first basic plumage, but the alar spots of both sexes have a more intense color and chin and throat of the female. The beige and brown edges of the male feathers disappear. Despite the fact that the brown or white tips on the feathers of the males are larger just after the molt and that they wear out throughout the year, the individuals vary considerably regarding the size of these non-black tips on the feathers in spring.


Wing feathers

Complete replacement of wing feathers takes about eight weeks. However, birds in their first year frequently retain some of the under-wing
coverts A covert feather or tectrix on a bird is one of a set of feathers, called coverts (or ''tectrices''), which, as the name implies, cover other feathers. The coverts help to smooth airflow over the wings and tail. Ear coverts The ear coverts are s ...
and juvenile tertiary remiges after post-juvenile
moulting In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...
. Of seventy immature males examined during the last week of October, it retained 70% of older lower primary blankets. In most cases where partial replacement of the covert feathers occurs, it is the proximal coverts that the bird retains.


Remiges

Primary remiges are one of the first feathers to molt. The molt of these feathers proceeds regularly from the innermost primary—primary I—to the outermost—primary IX. By October 1, most birds have either acquired the three new external primaries—VII, VIII, and IX—or they are at some advanced stage of development. The average dates for completion of the development of the new primary springs are: August 15 for primary I; September 1, primary II-IV; September 15, primary V and VI; and October 1, primaries VII-IX. The molting of the secondary remiges begins with the most external—secondary I— and proceeds inward to secondary VI. The secondary I sheath appears around the same time that all the secondary covers have been replaced and rarely before mid-August. These feathers are not completely renewed until the beginning of October. The molt of the tertiary remiges begins more or less at the same time as that of the secondary ones. The middle tertiary falls first, followed by the internal tertiary. Both feathers are often well developed again before the outer tertiary leaves the sheath.


Cover feathers and alula

The major primary blankets are changed along with their respective primary springs. Unlike the major primary coats, the major secondary coats molt earlier than the secondary spruces. The molting of these feathers is rapid, with several of them at the same stage of development simultaneously. The progression of the molt in these feathers is from the outside to the inside, as in the secondary remiges. Most birds has completed the change of the secondary coverts to August 15, more or less at the time is appreciable only secondary sheath remige I. The molting of the lesser coverts begins early, often being the first feathers to fall. The onset of molting in male juveniles is particularly noticeable because it involves the replacement of the minor covers and results in the appearance of the reddish or orange wing spot. The new wing spot contrasts sharply with the yellowish-brown juvenile plumage in this area of the wing. The move of the minor blankets has generally been completed by September 1. Alula feathers complete their development at about the same time as the last three primary sprouts. The marginal covers on the upper or outer surface of the forearm, located below the alula, shed at approximately the same time that the primary remix VI is being replaced. The first feathers under the wing to molt are the marginal coverts, under the forearm. The shedding of these feathers begins at about the same time that the primary remix IV falls and is followed by that of the lower middle primary and lower middle secondary coats. The progression of the molting of the lower middle secondary blankets is from the outside to the inside, while that of the lower middle primary mats seems to be irregular or almost simultaneous. The medial lower coverts molt before the primary remiges VIII and IX. The major lower primary coverts and major lower secondary coverts molt last. The progression of the molting of these last feathers is the same as in the primary and secondary sprouts, that is, from the inside out and from the outside in, respectively.


Flow and capital pens

The caudal feathers comprise the rudder or rectrix feathers and the upper and lower tail covers. The tail covers begin to shed before the rectrices. Generally, the upper tail covers begin to shed first. Certain birds lose some rectrices by the end of the third week of August. The helmsmen in the center of the queue are the last rectrices to be renovated. Molting in the capital region involves changing the feathers of the pileus and the sides of the head. It is one of the last parts of the body to begin feather replacement, but the renewal of most of the capital feathers is complete before that of the secondary feathers, tail feathers, and under-wing feathers. The beginning of the molt in this region coincides with the beginning of the development of the primary remige V or VI. Some individuals have already started replacing the capital feathers by mid-August. The molt begins at the pileus and the last areas of the capital region to complete it are the eye strip and the cheeks (malar region).


Other pens

In some birds, the first signs of molt in the ventral feathers appear during the last days of July, when the feathers of the anterior portion of the laterals begin to fall. From there, the molt progresses backward along the sides and forward toward the throat and chin. The last ventral feathers to be replaced are those towards the center of the abdomen. The molt of the dorsal feathers begins around the first week of August. It begins at the bladder, progresses to the upper back, and then to the cervical region. The earliest evidence of molting in the humeral plumes corresponds to the last days of July. The molt comes from the anterior region backwards. The change of the femoral feathers begins later than that of the humeral ones. However, the progression is similar. Replacement of feather feathers rarely begins before August 15. The progression is generally from the proximal end of the tibia to the tarsometatarsal region.


Distribution and habitat

The red-winged blackbird is widely spread throughout North America, except in the arid desert, high mountain ranges, and arctic or dense afforestation regions. It breeds from central-eastern Alaska and Yukon in the northwest, and Newfoundland in the northeast, to northern Costa Rica in the south, and from the Atlantic to the Pacific. Northern populations migrate to the southern United States, but those that breed there, in Mexico, and in Central America are sedentary. Red-winged blackbirds in the northern reaches of the range are migratory, spending winters in the southern United States and Central America. Migration begins in September or October, but occasionally as early as August. In western and Central America, populations are generally non-migratory. The red-winged blackbird inhabits open grassy areas. It generally prefers
wetlands A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...
, and inhabits both freshwater and saltwater
marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found at ...
es, particularly if
cattail ''Typha'' is a genus of about 30 species of monocotyledonous flowering plants in the family Typhaceae. These plants have a variety of common names, in British English as bulrush or reedmace, in American English as reed, cattail, or punks, in A ...
is present. It is also found in dry upland areas, where it inhabits meadows, prairies, and old fields. In a large part of its distribution area, it constitutes the most abundant passerine bird in the swamps in which it nests. It is also present in areas without much water, where it inhabits open fields – often agricultural areas – and sparse deciduous forests. In the winter of 1975–1976, near
Milan Milan ( , , Lombard: ; it, Milano ) is a city in northern Italy, capital of Lombardy, and the second-most populous city proper in Italy after Rome. The city proper has a population of about 1.4 million, while its metropolitan city h ...
(western
Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...
), red-winged blackbirds were observed resting in a mixed roost that came to house 11 million individuals in January and early February in a plantation of 4.5 hectares of yellow pine (Pinus taeda) with little undergrowth was seen in soybean fields during the day, being that these constituted only 21% of the habitat in the area and that the other bird species present in the roost were not commonly observed in these fields; they were also common in cornfields. the presences of the bird in
feedlot A feedlot or feed yard is a type of animal feeding operation (AFO) which is used in intensive animal farming, notably beef cattle, but also swine, horses, sheep, turkeys, chickens or ducks, prior to slaughter. Large beef feedlots are called conc ...
s has increased as winter progressed, but, accounting for less than 5% of the ichterids and starlings recorded in both feedlots of cows and pigs, they were much rarer there than the
brown-headed cowbird The brown-headed cowbird (''Molothrus ater'') is a small, obligate brood parasitic icterid native to temperate and subtropical North America. It is a permanent resident in the southern parts of its range; northern birds migrate to the southern ...
,
common grackle The common grackle (''Quiscalus quiscula'') is a species of large icterid bird found in large numbers through much of North America. First described in 1758 by Carl Linnaeus, the common grackle has three subspecies. Adult common grackles have a ...
and common starling.


Preferences by habitat types during the breeding season

During the breeding season, the density of breeding adults is much higher in swamps than in highland fields. Although the highest concentrations of nesting red-winged blackbird are found in swamps, most of them nest in upland habitats since they are much more abundant. In a study conducted in the
Wood County, Ohio Wood County is a county located in the U.S. state of Ohio. As of the 2020 census, the population was 132,248. Its county seat is Bowling Green. The county was named for Captain Eleazer D. Wood, the engineer for General William Henry Harriso ...
between 1964 and 1968, the density of territorial males in wetland habitat was found to be 2.89 times those in upland habitat. But, because of the small amount of wetland habitat, the total estimated upland population of territorial males was 2.14 times the wetland population.
Alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as w ...
(''Medicago sativa'') and other
legume A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock f ...
crops (hay) were the principal habitat for breeding redwings in the county. Despite the marked preference for wetland habitats, the greater population in uplands reflects wetlands' scarcity.


Vegetation type preferences during the breeding season

In that same study, reproductive individuals in upland habitats demonstrated a slight preference for old and new grasses such as ''
Phleum pratense Timothy (''Phleum pratense'') is an abundant perennial grass native to most of Europe except for the Mediterranean region. It is also known as timothy-grass, meadow cat's-tail or common cat's tail. It is a member of the genus ''Phleum'', consis ...
'', ''
Dactylis glomerata ''Dactylis Glomerata'' is the sixth studio album by Swedish doom metal band Candlemass, released in 1998. This was their first album released since their split in 1994. The album was originally destined to be the second release by Candlemass ...
'', '' Poa'' spp., ''
Festuca ''Festuca'' (fescue) is a genus of flowering plants belonging to the grass family Poaceae (subfamily Pooideae). They are evergreen or herbaceous perennial tufted grasses with a height range of and a cosmopolitan distribution, occurring on every ...
'' spp., and ''
Bromus ''Bromus'' is a large genus of grasses, classified in its own tribe Bromeae. They are commonly known as bromes, brome grasses, cheat grasses or chess grasses. Estimates in the scientific literature of the number of species have ranged from 100 ...
'' spp. In the early part of the breeding season and new non-graminoid herbaceous plants in the mid and late season. In wetlands, they consistently preferred old and new broadleaf
monocotyledon Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of ...
s, primarily ''
Carex ''Carex'' is a vast genus of more than 2,000 species of grass-like plants in the family Cyperaceae, commonly known as sedges (or seg, in older books). Other members of the family Cyperaceae are also called sedges, however those of genus ''Carex'' ...
'' spp, broadleaf, and ''
Typha ''Typha'' is a genus of about 30 species of monocotyledonous flowering plants in the family Typhaceae. These plants have a variety of common names, in British English as bulrush or reedmace, in American English as reed, cattail, or punks, in A ...
'' spp, and consistently rejected old and new narrow-leaved monocots, primarily narrow-leaved ''
Phalaris arundinacea ''Phalaris arundinacea'', or reed canary grass, is a tall, Perennial plant, perennial bunchgrass that commonly forms extensive single-species stands along the margins of lakes and streams and in wet open areas, with a wide distribution in Europe ...
'' and ''
Calamagrostis canadensis ''Calamagrostis canadensis'' is a species of grass, having three or more varieties, in the family Poaceae. It is known variously by the common names of bluejoint, bluejoint reedgrass, marsh reedgrass, Canadian reedgrass, meadow pinegrass, and m ...
'', and non-graminoid herbaceous plants. Red-winged blackbirds breeding in the highlands favored older tall vegetation only in the early part of the breeding season on April to May, and higher new vegetation and dense vegetation throughout the breeding season. For their part, those who settled in wetlands seemed to have a slight predilection for taller old vegetation. During the breeding season, this species is attracted to tall vegetation that restricts visibility. Early season preferences for old grassland in the highlands and old broadleaf monocotyledons in wetlands point to the importance of upright residual vegetation. Highland grasses and broadleaf monocots in wetlands stand partially vertically and are easily visible in early spring, unlike
clovers Clover or trefoil are common names for plants of the genus ''Trifolium'' (from Latin ''tres'' 'three' + ''folium'' 'leaf'), consisting of about 300 species of flowering plants in the legume or pea family Fabaceae originating in Europe. The genus ...
, narrow-leaved monocotyledons in wetlands and most non-graminoid herbaceous plants. Old alfalfa plants are also partially upright in early spring, but they are not as consistently chosen a species as old grasses. The start of the territorial activity is earlier when the amount of residual vegetation is large. Vegetation structural strength also appears to be important for nesting as females tend to broadleaf monocotyledons in wetlands throughout the breeding season and new non-graminoid herbaceous plants in the mid to late season. In southwestern Michigan, the density of cattail stems in different ponds was positively related to the concentration of reproductive adults. However, other studies detected a predilection for more scattered vegetation. One found that red-winged blackbirds avoided the
marsh wren The marsh wren (''Cistothorus palustris'') is a small North American songbird of the wren family. It is sometimes called the long-billed marsh wren to distinguish it from the sedge wren, also known as the short-billed marsh wren. Taxonomy The ma ...
(''Pantaneros chivirenes''), a predator common in nests of this species, reproducing among more dispersed vegetation, which was more easily defended from the chivirines; conversely, the chivirines seemed to prefer the denser vegetation, where they were more likely to avoid the aggressiveness of the red-winged blackbird; These differences in habitat selection between one species and another resulted in spatial segregation of their breeding areas. On the other hand, red-winged blackbirds tend to opt for small lots of vegetation and plants with thick stems.


Behavior

The red-winged blackbird is territorial, polygynous, gregarious and a short-distance migratory bird. Its way of flying is characteristic, with rapid wing flaps punctuated by brief periods of gliding flight. The behavior of males makes their presence easily perceived: they perch in high places such as trees, bushes, fences, telephone lines, etc. Females tend to stay low, prowling through the vegetation and building their nests. They can be found in home gardens, particularly during their migration, if seeds have been scattered on the ground. The forest curtains serve as a resting place during the day. For several weeks after their first appearance in early spring, red-winged blackbirds are generally seen in flocks made up entirely of males. During those days, they are seldom seen at their breeding sites, except early morning and late afternoon. In most of the remaining hours of the day, they frequent open and often elevated agricultural land, where they feed mainly on grain stubble and grassy fields. When disturbed while eating, they fly to the nearest deciduous trees and immediately after landing they begin to sing.


Food

The red-winged blackbird is
omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutri ...
. It feeds primarily on plant materials, including
seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
s from weeds and waste grain such as corn and rice, but about a quarter of its diet consists of insects and other small animals, and considerably more so during breeding season. It prefers insects, such as
dragonflies A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of true dragonfly are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threa ...
,
damselflies Damselflies are flying insects of the suborder Zygoptera in the order Odonata. They are similar to dragonflies, which constitute the other odonatan suborder, Anisoptera, but are smaller and have slimmer bodies. Most species fold the wings along ...
,
butterflies Butterflies are insects in the macrolepidopteran clade Rhopalocera from the Order (biology), order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The ...
,
moths Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
, and
flies Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...
, but also consumes
snail A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gastro ...
s, frogs,
egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...
s,
carrion Carrion () is the decaying flesh of dead animals, including human flesh. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures, c ...
, worms, spiders,
mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000  extant species of molluscs are recognized. The number of fossil species is e ...
s. The red-winged blackbird forages for insects by picking them from plants, or by catching them in flight. Sometimes insects are obtained by exploring the bases of aquatic plants with their small beaks, opening holes to reach the insects hidden inside. Aquatic insects, particularly odonates emerging, are of great importance in the diet of red-winged blackbirds that breed in swamps. These birds typically capture the odonates when the larvae climb up the stem of a plant from the water, get rid of their exuviae, and cling to the vegetation while their exoskeletons harden. The years of emergence of
Periodical cicadas The term periodical cicada is commonly used to refer to any of the seven species of the genus ''Magicicada'' of eastern North America, the 13- and 17-year cicadas. They are called periodical because nearly all individuals in a local population ...
, it provides an overabundant amount of food. In season, they also eat blueberries, blackberries and other fruits. According to
Edward Howe Forbush Edward Howe Forbush (April 24, 1858 – March 7, 1929) was a noted Massachusetts ornithologist and a prolific writer, best known for his book ''Birds of New England''. Biography Born in Quincy, Massachusetts, in 1858, he was a precocious na ...
, when they arrive north in the spring, they feed in the fields and meadows. Then, they follow the plows, collecting larvae, earthworms and caterpillars left exposed, and in case there is a plague of
Paleacrita vernata ''Paleacrita vernata'', the spring cankerworm, is a moth of the family Geometridae. The species was first described by William Dandridge Peck in 1795. It is found in North America from the Atlantic Ocean west to Alberta, Texas and California. T ...
caterpillars in a fruit orchard, these birds will fly a kilometer to get them for their chicks. In season, it eats blueberries,
blackberries The blackberry is an edible fruit produced by many species in the genus ''Rubus'' in the family (biology), family Rosaceae, hybrids among these species within the subgenus ''Rubus'', and hybrids between the subgenera ''Rubus'' and ''Idaeobatus' ...
, and other fruit. These birds can be lured to backyard
bird feeder A birdfeeder, bird table, or tray feeder are devices placed outdoors to supply bird food to birds (bird feeding). The success of a bird feeder in attracting birds depends upon its placement and the kinds of foods offered, as different species h ...
s by bread and seed mixtures and
suet Suet is the raw, hard fat of beef, lamb or mutton found around the loins and kidneys. Suet has a melting point of between 45 °C and 50 °C (113 °F and 122 °F) and congelation between 37 °C and 40 °C (98.6& ...
. In late summer and in autumn, the red-winged blackbird will feed in open fields, mixed with
grackle Grackles is the common name of any of 11 passerine birds (10 extant and one extinct) native to North and South America. They belong to various genera in the icterid family. In all the species with this name, adult males have black or mostly blac ...
s,
cowbird Cowbirds are birds belonging to the genus ''Molothrus'' in the family Icteridae. They are of New World origin, and are obligate brood parasites, laying their eggs in the nests of other species. The genus was introduced by English naturalist Will ...
s, and
starling Starlings are small to medium-sized passerine birds in the family Sturnidae. The Sturnidae are named for the genus ''Sturnus'', which in turn comes from the Latin word for starling, ''sturnus''. Many Asian species, particularly the larger ones, ...
s in flocks which can number in the thousands. It feeds on corn while it is maturing; once the grain has hardened it is relatively safe from this bird, since its beak and digestive system are not adapted for the consumption of hard and whole corn grains, unlike the Common grackle, which has a longer and stronger beak. Studies of the stomachs of individuals of both sexes reveal that males consume higher proportions of crop grains, while females ingest a relatively larger amount of herb seeds and animal matter. In the winter of 1975–1976, near Milan, western Tennessee, corn and herb seeds were the main foods consumed by red-winged blackbird. Herbs whose seeds were commonly consumed were
Sorghum halepense Johnson grass or Johnsongrass, ''Sorghum halepense'', is a plant in the grass family, Poaceae, native to Asia and northern Africa. The plant has been introduced to all continents except Antarctica, and most larger islands and archipelagos. It re ...
,
Xanthium strumarium ''Xanthium strumarium'' (rough cocklebur, clotbur, common cocklebur, large cocklebur, woolgarie bur) is a species of annual plants of the family Asteraceae. Some sources claim it originates in southern Europe and Asia, but has been extensively na ...
,
Digitaria ischaemum ''Digitaria ischaemum'' is a species of crabgrass known by the common names smooth crabgrass and small crabgrass. It is native to Europe and Asia, but it is known throughout much of the warm temperate world as an introduced species and often a co ...
,
Sporobolus ''Sporobolus'' is a nearly cosmopolitan genus of plants in the grass family. The name ''Sporobolus'' means "seed-thrower", and is derived from Ancient Greek word (), meaning "seed", and the root of () "to throw", referring to the dispersion of ...
spp.,
Polygonum ''Polygonum'' is a genus of about 130 species of flowering plant in the buckwheat and knotweed family Polygonaceae. Common names include knotweed and knotgrass (though the common names may refer more broadly to plants from Polygonaceae). In the ...
spp. and
Amaranthus ''Amaranthus'' is a cosmopolitan genus of annual or short-lived perennial plants collectively known as amaranths. Some amaranth species are cultivated as leaf vegetables, pseudocereals, and ornamental plants. Catkin-like cymes of densely pac ...
spp.


Breeding

The red-winged blackbird nests in loose
colonies In modern parlance, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the '' metropolitan state'' ...
. The nest is built in cattails, rushes, grasses, sedge, or alder or willow bushes. The nest is constructed entirely by the female over the course of three to six days. It is a basket of grasses, sedge, and mosses, lined with mud, and bound to surrounding grasses or branches. It is located to above water. A clutch consists of three or four, rarely five,
egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...
s. Eggs are oval, smooth and slightly glossy, and measure . They are pale bluish green, marked with brown, purple, and/or black, with most markings around the larger end of the egg. These are incubated by the female alone, and hatch in 11 to 12 days. Red-winged blackbirds are hatched blind and naked, but are ready to leave the nest 11 to 14 days after hatching. Red-winged blackbirds are polygynous, with territorial males defending up to 10 females. However, females frequently copulate with males other than their social mate and often lay clutches of mixed
paternity Paternity may refer to: *Father, the male parent of a (human) child *Paternity (law), fatherhood as a matter of law * ''Paternity'' (film), a 1981 comedy film starring Burt Reynolds * "Paternity" (''House''), a 2004 episode of the television seri ...
. Pairs raise two or three clutches per season, in a new
nest A nest is a structure built for certain animals to hold eggs or young. Although nests are most closely associated with birds, members of all classes of vertebrates and some invertebrates construct nests. They may be composed of organic materia ...
for each clutch. The reproductive season of the red-winged blackbird extends approximately from the end of April to the end of July. On the other hand, in different states has been estimated that the period in which the active nests contained eggs lay between beginning in late April and early late August; and in northern
Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is borde ...
nests were found to harbor chicks from late April to late July. The peak of the nesting season (the time with the highest number of active nests) has been recorded between the first half of May and the beginning of June in different places. A study in eastern Ontario found that although red-winged blackbirds began nesting earlier in years with warm springs, associated with low winter values in the
North Atlantic Oscillation The North Atlantic Oscillation (NAO) is a weather phenomenon over the North Atlantic Ocean of fluctuations in the difference of atmospheric pressure at sea level (SLP) between the Icelandic Low and the Azores High. Through fluctuations in the ...
Index, egg laying dates remained unchanged. Male testosterone levels peak in the early part of the breeding season, but remain high throughout the season. Females reproduce for up to ten years. Many aspects of
territorialism Territorialism can refer to: * Animal territorialism, the animal behavior of defending a geographical area from intruders * Environmental territorialism, a stance toward threats posed toward individuals, communities or nations by environmental even ...
(for example, the number of male songs and displays, and the number of intrusions into foreign territories) peak before mating. After this, the frequency of many of the territorial behaviors decreases and the males are mainly concerned with defending the females, eggs, and chicks against predation. Experiments in the systematic removal of birds from their territories suggest that the extra population of males that is present in swamps before copulations disappears after copulation. Predation of eggs and nestlings is quite common. Nest predators include snakes,
mink Mink are dark-colored, semiaquatic, carnivorous mammals of the genera ''Neogale'' and '' Mustela'' and part of the family Mustelidae, which also includes weasels, otters, and ferrets. There are two extant species referred to as "mink": the A ...
,
raccoon The raccoon ( or , ''Procyon lotor''), sometimes called the common raccoon to distinguish it from other species, is a mammal native to North America. It is the largest of the procyonid family, having a body length of , and a body weight of ...
s, and other birds, even as small as
marsh wren The marsh wren (''Cistothorus palustris'') is a small North American songbird of the wren family. It is sometimes called the long-billed marsh wren to distinguish it from the sedge wren, also known as the short-billed marsh wren. Taxonomy The ma ...
s. The red-winged blackbird is occasionally a victim of brood parasites, particularly
brown-headed cowbird The brown-headed cowbird (''Molothrus ater'') is a small, obligate brood parasitic icterid native to temperate and subtropical North America. It is a permanent resident in the southern parts of its range; northern birds migrate to the southern ...
s. Since nest predation is common, several adaptations have evolved in this species. Group nesting is one such trait which reduces the risk of individual predation by increasing the number of alert parents. Nesting over water reduces the likelihood of predation, as do alarm calls. Nests, in particular, offer a strategic advantage over predators in that they are often well concealed in thick, waterside reeds and positioned at a height of one to two meters. Males often act as sentinels, employing a variety of calls to denote the kind and severity of danger.
Mobbing Mobbing, as a sociological term, means bullying of an individual by a group, in any context, such as a family, peer group, school, workplace, neighborhood, community, or online. When it occurs as physical and emotional abuse in the workplace, suc ...
, especially by males, is also used to scare off unwanted predators, although mobbing often targets large animals and man-made devices by mistake. The brownish coloration of the female may also serve as an anti-predator trait in that it may provide camouflage for her and her nest while she is incubating.


Predators and parasites

Predators of red-winged blackbirds include such species as
raccoons The raccoon ( or , ''Procyon lotor''), sometimes called the common raccoon to distinguish it from other species, is a mammal native to North America. It is the largest of the procyonid family, having a body length of , and a body weight of . ...
,
American mink The American mink (''Neogale vison'') is a semiaquatic species of mustelid native to North America, though human intervention has expanded its range to many parts of Europe, Asia and South America. Because of range expansion, the American mink i ...
,
long-tailed weasel The long-tailed weasel (''Neogale frenata''), also known as the bridled weasel, masked ermine, or big stoat, is a species of mustelid distributed from southern Canada throughout all the United States and Mexico, southward through all of Central A ...
s,
Eurasian magpie The Eurasian magpie or common magpie (''Pica pica'') is a resident breeding bird throughout the northern part of the Eurasian continent. It is one of several birds in the crow family (corvids) designated magpies, and belongs to the Holarctic ra ...
s,
common grackle The common grackle (''Quiscalus quiscula'') is a species of large icterid bird found in large numbers through much of North America. First described in 1758 by Carl Linnaeus, the common grackle has three subspecies. Adult common grackles have a ...
s, owls,
red-tailed hawk The red-tailed hawk (''Buteo jamaicensis'') is a bird of prey that breeds throughout most of North America, from the interior of Alaska and northern Canada to as far south as Panama and the West Indies. It is one of the most common members with ...
s, short-tailed hawks, and snakes (such as the
northern water snake The common watersnake (''Nerodia sipedon'') is a species of large, nonvenomous, common snake in the family Colubridae. The species is native to North America. It is frequently mistaken for the venomous cottonmouth (''Agkistrodon piscivorus''). ...
and the
plains garter snake The plains garter snake (''Thamnophis radix'') is a species of garter snake native to most of the central United States as far north as Canada and as far south as Texas. It has a distinctive orange or yellow stripe from its head to tail, and the ...
). Ravens and grazers such as marsh wrens feed on eggs (and even small chicks), if the nest is left unattended, destroying the eggs, occasionally drinking from them, and pecking the nestlings to death. The relative importance of different nest predators varies by geographic region: the top predators in different regions include the marsh wren in British Columbia, the magpies in Washington, and the raccoons in Ontario. The incidence of avian predation in red-winged blackbird nests is higher in western populations than in eastern populations. Due to high predation rates, especially of eggs and chicks, the red-winged blackbird has developed various
adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...
s to protect its nests. One of them consists of nesting in groups, which reduces the danger since there is a greater number of alert parents. Nesting over water also lowers the chances of an attack. Nests in particular offer a strategic advantage as they are often hidden among dense riparian reeds, at a height of one or two meters. males often act as sentinels, using a repertoire of calls. Males in particular hunt down potential predators to scare them away, even when dealing with much larger animals. Aggressiveness of the red-winged blackbird towards the marsh wren, which also nests in swamps, causes a partial interspecies territorialism. On the other hand,
nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...
predators such as raccoons and American mink are not attacked by adults. Coloration of the female could serve to
camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the ...
it, protecting it and its nest when it is incubated. The red-winged blackbird can accommodate
ectoparasites Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...
such as various ''
Phthiraptera Louse ( : lice) is the common name for any member of the clade Phthiraptera, which contains nearly 5,000 species of wingless parasitic insects. Phthiraptera has variously been recognized as an order, infraorder, or a parvorder, as a result of ...
'', the ''
Ischnocera The Ischnocera is a large superfamily of lice. They are mostly parasitic on birds, but including a large family (the Trichodectidae) parasitic on mammals. The genus '' Trichophilopterus'' is also found on mammals (lemurs), but probably belongs ...
'' ''Philopterus agelaii'' and ''Brueelia ornatissima'', and
hematophagous Hematophagy (sometimes spelled haematophagy or hematophagia) is the practice by certain animals of feeding on blood (from the Greek words αἷμα ' "blood" and φαγεῖν ' "to eat"). Since blood is a fluid tissue rich in nutritious p ...
mites, like ''Ornithonyssus sylviarum'', and
endoparasites Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...
like ''Haemoproteus quiscalus'', ''Leucocytozoon icteris'', ''Plasmodium vaughani'',
nematodes The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a broa ...
,
fluke Fluke may refer to: Biology * Fluke (fish), a species of marine flatfish * Fluke (tail), the lobes of the tail of a cetacean, such as dolphins or whales, ichthyosaurs, mosasaurs Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Greek ...
s and
tapeworms Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, known as tapeworms. Their bodies consist of man ...
.


Territorial

The red-winged blackbird aggressively defends its territory from other animals, and will attack much larger birds. During breeding season, males will swoop at humans who encroach upon their nesting territory. Male red-winged blackbirds also exhibit important territorial behaviors, most of which provides them with the necessary fidelity for many years to come. A few important factors for male red-winged blackbirds’ adherence to territories include food, hiding spaces from predators, types of neighbors, and reactions towards predators. Additionally, a study was done on site fidelity and movement patterns by Les D. Beletsky and Gordon H. Orians in 1987 which explained much of the males’ territorial behaviors once migrated and settled onto a territory of their own. Sufficient evidence had shown that males are committed to staying in their territory over a long period of time and are not more likely to change territories at a younger age due to limited experience of knowledge for success. Studies also showed that most of the males that were first-time movers to a new territory were between two and three years old. The majority of males that moved were young and inexperienced. Later on they had moved towards more available territories. If males had chosen to leave their territory for reproductive success, as an example, they would do so within a short distance. Males who moved shorter distances were more successful in reproducing than those who moved longer distances. Further studies showed that when males moved further away from their territories there was a decrease in probability of successfully fledging. The maximum longevity of the red-winged blackbird in the wild is 15.8 years.


Migration

Red-winged blackbirds that breed in the northern part of their range, i.e., Canada and border states in the United States, migrate south for the winter. However, populations near the Pacific and Gulf coasts of North America and those of Middle America are year-round resident. Red-winged blackbirds live in both Northern U.S. and Canada, ranging from Yucatan Peninsula in the south to the southern part of Alaska. These extensions account for the majority of the continent stretching from California's Pacific coast and Canada to the eastern seaboard. Much of the populations within Middle America are non-migratory. During the fall, populations begin migrating towards Southern U.S. Movement of red-winged blackbirds can begin as early as August through October. Spring migration begins anywhere between mid-February to mid-May. Numerous birds from northern parts of the U.S., particularly the Great lakes, migrate nearly between their breeding season and winter Winter territorial areas differ based on geographic location. Other populations that migrate year-round include those located in Middle America or in the western U.S. and Gulf Coast. Females typically migrate longer distances than males. These female populations located near the Great Lakes migrate nearly farther. Yearly-traveled females also migrate further than adult males, while also moving roughly the same distance as other adult females. Red-winged blackbirds migrate primarily during daytime. In general, males’ migration flocks arrive prior to females in the spring and after females in the fall.


Ecological and economic impact

According to the American
ornithologist Ornithology is a branch of zoology that concerns the "methodological study and consequent knowledge of birds with all that relates to them." Several aspects of ornithology differ from related disciplines, due partly to the high visibility and th ...
Arthur Cleveland Bent Arthur Cleveland Bent (November 25, 1866 – December 30, 1954) was an American ornithologist. He is notable for his encyclopedic 21-volume work, ''Life Histories of North American Birds'', published 1919-1968 and completed posthumously. Bent ...
, in the northern regions of its range the eastern red-winged blackbird is almost completely beneficial from an economic perspective and there are comparatively few complaints of severe crop damage. Their diet consists almost entirely of insects, very few of which are useful species, and herb seeds. However, it causes certain damages to the grains that germinate in spring and to sweet corn in summer, while the grains are still soft, tearing the foliaceous covering of the ears and ruining them from a commercial point of view. It also attacks other grains in a limited way, but most of what it consumes is waste left in the ground. In the Midwest, where these birds are much more abundant and where cereals are grown more extensively than in the North, red-winged blackbirds and other ichterids, in late summer and fall, do great damage to grain fields, both while they are maturing as when they are harvested . However, it has been claimed that even there are beneficial because the larvae harmful than removed from corncobs and plants beet and can counteract pests of caterpillars. In the southern states, they seriously harm rice by plucking seedlings in spring and eating the still-soft grains as they mature, being in this sense almost as harmful as the Bobolink. On the other hand, they are of some use in consuming the weed seeds that would otherwise devalue the product. Being one of the most numerous birds on the continent, it plays an important role in the dispersal of other species. Since red-winged blackbirds gather and rest in such large numbers, the survival of certain species that join their flocks is likely to be affected by their company. They can also be an important source of food for animals such as raccoons and mink. Likewise, populations that nest and rest in swamps could cushion the effect of predation on duck species and other animals. In summary, these birds are so numerous and active that their mere presence and natural behavior is enough to influence the environment in a visible way.


Positives: weed control and harmful insects

Through the control of insect populations through predation and unwanted herbs with the consumption of their seeds, they allow the growth of larger plants and crops. They also eat on Anthonomus grandis and Hypera postica, two species of weevils affecting cotton and alfalfa respectively, as well as harmful caterpillars of the European gypsy moth (Lymantria dispar) and of the genus Malacosoma. In some areas of the southern United States, the seeds of the common plumber (
Xanthium strumarium ''Xanthium strumarium'' (rough cocklebur, clotbur, common cocklebur, large cocklebur, woolgarie bur) is a species of annual plants of the family Asteraceae. Some sources claim it originates in southern Europe and Asia, but has been extensively na ...
), a weed detrimental to soybeans and cotton, seems to be an important food source for the species. During the breeding season, the approximately 8 million red-winged blackbirds nesting in Ohio and their chicks probably consume more than of insects, an average of almost . Many of these insects, such as the weevils (Hypera spp.), Come from alfalfa fields, pastures, oat fields and other crops. In cornfields, blackbirds often feed on corn worms (Helicoverpa zea) and beetles of the genus Diabrotica. In early spring, red-winged blackbirds consume corn borers (Ostrinia nubilalis) in fields with corn stubble. However, Bendell et al. (1981) found that the economic benefit of pest control, such as larvae of that lepidopteran, by the red-winged blackbird only compensated for 20% of the damage to crops caused by this bird.


Negative aspects: consumption of cultivated grains

The red-winged blackbirds can devastate farm fields. Despite the fact that they consume weed seeds, they are known to cause great damage to agriculture due to their habits of resting in massive groups and their taste for agricultural products. may be also causes harm to plantings corn, rice, sunflower and sorghum, particularly important near roosts. Red-winged blackbird is the largest species of Icterid in North America and the most damaging to crops. From 215 birds Neotropical migrants have been identified as causing, by a wide margin, the greatest economic loss. In North America, the damage to corn crops by this species has increased since the late 1960s to early 1980s, perhaps because of the increase in the area for grain production, and due to the reduction of small areas with stubble, hayfields and uncultivated land, which, in turn, accentuated the bird's dependence on corn to ensure its livelihood. Apparently, the male does more damage to this grain than the female. In some areas of Ohio, corn can account for up to 75% of the diet of males and only 6% of that of females in August and September. In South Dakota, in the late summer, the Gizzards of the males studied contained 29% corn, while in the case of the female that number was limited to 9%.


Situation in the Midwest

The red-winged blackbird is the dominant species in the large concentrations of blackbirds that feed on the fields of sunflower, corn and small grains maturing in late summer or early fall in the Dakotas. In the 1970s, losses to sunflower and corn crops caused by blackbirds in the Dakotas exceeded $3 million annually for each case. In the northern part of the Great Plains, an area known as the Prairie Pothole Region, in red-winged blackbirds are very abundant in summer, they congregate in post-reproductive flocks that significantly harm crops, particularly sunflower plantations near their home sites. Most sunflower damage occurs between mid-August and early September, when the calorie content of immature seeds is low and birds must consume more of them to satiate themselves. During this initial stage of predation on sunflower crops in which more than 75% of the total damage is caused, the red-winged blackbird represent 80% of the blackbirds observed in the fields of this seed. This period predates the massive migration of birds and most of them are of local origin. Most remain within of their native sites until the molting of their feathers is complete or nearly complete in late August or early September. Damage can be quite serious in the center and southeast of North Dakota and Northeast South Dakota, areas of high concentration of sunflower production and abundant wetlands that attract red-winged blackbird during the breeding season. Investigations conducted between 1968 and 1979 revealed that blackbirds, notably the black-winged blackbird and the Common grackle, annually destroyed less than 1% of corn crops in Ohio, amounting to a loss between 4 and 6 million dollars according to 1979 prices. Insects, weeds, diseases and fungi. They are likely to cause losses of more than 20% of the total potential maize harvest in the Midwest states, and harvesting procedures often leave 5% or more of the maize in the fields, revealing that comparative damage by Ichteridae in Ohio is not great. However, the average damage caused by these birds is not of as much economic importance as its distribution among producers. While 97.5% of cornfields studied in Ohio suffered a loss of less than 5%, which constituted about 60% of the total damage in the state, the remaining 2.5% often incurred losses of more than 5% and represented approximately 40% of total injury in Ohio. All Ohio counties experience some degree of predation on their maize crops from blackbirds, but those most affected are a few counties where marshes that roost them still abound. The counties of Ottawa, Sandusky and Lucas, on the waters of Sandusky Bay and Lake Erie, were the hardest hit. These three counties, among the 19 studied between 1968 and 1976, contained 62% of the fields in which the losses exceeded 5% and 77% of those in which they exceeded 10%. Other counties with extensive localized damage were Erie, Ashtabula also located on the coasts of the mentioned water courses and Hamilton. Almost all the plantations with damages greater than 5% were within of some important roosting of blackbirds. In the 1968–1976 period, in northeast Sandusky County and northwest Ottawa, where large roosts of up to a million birds were discovered in late summer and fall, average losses exceeded 9% in fields from the roosts, but they were less than 5% at and less than 2% at . In southwestern Ontario, in the summer of 1964, it was found that the greatest damage to the cornfields by red-winged blackbird also occurred near roosts in swamps.


Pest control

The two main options that farmers can choose from to avoid the presence of birds once corn has entered the milky stage of its maturation process are the use of the chemical 4-aminopyridine and the implementation of mechanical devices to frighten birds away. The time chosen to take measures to disperse the blackbirds is of great importance since once the birds have chosen a field to feed there they are likely to return for several days. The longer be allowed to feed them unmolested, will become more difficult to scare them away. Also, most of the damage is inflicted in just a few days, when the pimples are soft; consequently, control techniques will not be very useful if applied after this period.


Pest control history

As early as 1667, Massachusetts Bay settlers had enacted laws to try to reduce blackbird populations and mitigate damage to corn. According to Henry David Thoreau, a law provided that each single man in a town must kill six of those birds and, as a punishment for not doing so, he could not marry until he had complied with the aforementioned design. Obviously, since blackbirds reproduce at a much higher speed than humans marry, this control strategy was a failure. Pioneers traveling west to the Great Lakes region faced similar problems. By 1749, blackbirds were so abundant around western Lake Erie that people took turns watching over the maturing grain crops. At the beginning of the 20th century, in some places, when the reeds dried up, these circumstances were used to kill these birds in the following way. A crew approached a roost in silence, hidden in the darkness of the night, and simultaneously lit the reeds at various points, which were quickly enveloped by a single great flame. This caused a huge tumult among the red-winged blackbird, which, lit by fire, were shot down in large numbers as they hovered in midair and screamed all over the place. Sometimes straw was used for the same purpose, which was previously scattered near reeds and alder bushes (Alnus spp.) in which they gathered to rest, the burning of which caused great consternation among the birds. The gang returned the next day to collect the hunted prey. Arthur Cleveland Bent says that, before it was banned the sale of prey hunting in the market, red-winged blackbirds were massacred in large numbers in autumn and sold in markets. When they had put on weight on a diet of grains or rice, their small bodies were served as delicious snacks on the gourmet tables . Few could distinguish them from charlatans (Dolichonyx oryzivorus). In 1926, when the US Biological Survey – predecessor of the United States Fish and Wildlife Service carried out its first compilation of roosts of undesirable ichterids, it was recorded in Ohio, with its large populations of these birds and the fifth largest area allocated to the cultivation of corn among the American states, a number of complaints higher than in any other state. During the 1950s, bird control committees were organized in some counties to deal with the damage to maize caused by blackbirds and the Ohio Agricultural Experiment Station now the Ohio Agricultural Research and Development Center and the Department of Zoology and Entomology of the state university began investigating the problem.


Use of deadly traps and chemicals

Crop predation has led to the use of traps, poison and surfactants by farmers in an attempt to control populations of red-winged blackbirds; these last properties suppress waterproof feathers, making them extremely vulnerable to the cold, but their effectiveness depends on certain atmospheric conditions, namely low temperatures and rainfall. Programs in which baits were used poisoned to reduce icteride concentrations in late summer have been unsuccessful. While thousands of birds have occasionally died, the effect on large roosting-associated flocks that sometimes contain more than a million individuals is small; In addition, specimens of other species frequently die. The use of large lure traps, which often catch hundreds of birds per day, is also ineffective against these large flocks.


Use of 4-aminopyridine

4-Aminopyridine is applied to one in one hundred particles of ground corn used as bait. Generally, corn is thrown into the fields from planes that release a load of about of bait per hectare on one third of the land. Because that amount of ground corn contains around 205,000 particles, approximately 2050 toxic particles are distributed per hectare treated. The ingestion of one or more of these particles by a blackbird causes erratic flight, calls for suffering and finally death; that behavior often leads the remaining birds in the flock to leave the field. The chemical DRC-1327, which has proven useful in mitigating damage to maturing corn, operates in the same way: when a bird ingests kernels from a partially hand-peeled cob to which the chemical has been applied with a sprayer manual, his erratic flight and his pre-death calls for suffering, which span a space of between five and fifteen minutes, chase away flocks from the fields. The initial application of 4-aminopyridine should be carried out as soon as possible after the start of the milky stage of the grain ripening process. Two other booster applications five to seven days apart are generally recommended; Often just one is sufficient, but under conditions of prolonged bird activity more than three applications may be required at shorter intervals. In Brown County, South Dakota, Brown County (Northeast South Dakota), in 1965, hand-spread 4-aminopyridine baits at intervals of about one week reduced projected red-winged blackbird loss by maturing corn crops by 85%. The distressing behavior exhibited by the individuals affected by the chemical produced a marked fear response in other members of the flocks and the fields were free of red-winged blackbirds even when the estimated directly affected proportion was less than 1%. It has even been suggested that the continued use of 4-aminopyridine over the years could cause a change in the pattern of migration to the south, as if birds were learning to avoid areas persistently treated with the chemical. In another experiment in the same county, the number of blackbirds making use of the treated area fell dramatically over a period of five days after treatment had begun and remained low for the remainder of the season of damage to cornfields. The results of this method were largely limited to icterides. Although common pheasant were abundant, there was no evidence that any were affected, and mortality among other bird species was negligible. The abundance of weeds should be considered as restricting the chances that birds will find bait particles scattered on the ground, so the use of this chemical must be accompanied by a weed control program. A less obvious problem is that of the insects that remove the bait. If Gryllus are detected in a field, ground corn is expected to disappear quickly. Crickets generally select untreated particles and leave the toxic ones behind; however, the rapid decrease in the total volume of ground corn on the ground decreases the attractiveness of ground-level feeding for blackbirds. Because cricket populations are difficult to control, more frequent applications or other bird control techniques may be desirable under these circumstances. A third problem is that of heavy rains, which cover the bait with soil or drag it into cracks in the ground. Likewise, a low population density of ichterides can reduce the effectiveness of its control with 4-aminopyridine.


Non-lethal methods

A variety of devices to repel them, including electronic noise-making systems, helium balloons tied in the fields, radio-controlled aircraft, and various types of scarecrows are occasionally used in cornfields. Methods such as scarecrows, pyrotechnics, and propane cannons, may help mitigate mild predation, but only work effectively if the duration of the damage period is less than that of the birds becoming accustomed to these methods. Red-winged blackbirds quickly become accustomed to them, particularly if the crop is a prime food source in an area with few alternative sources of livelihood. Although harvesting as early as possible after the corn has dried sufficiently can limit damage by northern grazing flocks, adjusting the harvest date does not help farmers reduce losses by red-winged blackbirds during the milky stage. One approach that has been successful in controlling roosts in the highlands is dispersal of populations through habitat alteration or bird harassment. These procedures, carried out by biologists in cooperation with local citizens, have been successful in dispersing or displacing populations of up to one million individuals. Although this dispersion can sometimes move the problem from one place to another – especially when the area has been intensively cultivated with corn and alternative food sources are not abundant, it has often been effective in solving local problem situations. Because oats and wheat grains in already harvested fields constitute an important food for blackbirds in late summer, the postponement of plowing the land with small grain stubble can lessen the pressure exerted by the predation of these birds on the maturing corn. The natural existence or planting of plants such as millet, sorghum (Sorghum spp.), Polygons (
Polygonum ''Polygonum'' is a genus of about 130 species of flowering plant in the buckwheat and knotweed family Polygonaceae. Common names include knotweed and knotgrass (though the common names may refer more broadly to plants from Polygonaceae). In the ...
spp.) And various grasses for example, mohas (Setaria spp.) that could be beneficial. As a general ecological principle, diversity in the types of habitats that can be maintained in regions of intense agricultural activity is related to a greater probability that the damages caused by pests are restricted to economically tolerable levels. Studies in sweet corn fields indicate that blackbirds could often be initially attracted to maturing crops by insects. Flocks can wander the land cultivated for about a week consuming insects and weed seeds before attacking the corn. Diabrotica beetles may be especially attractive during this period. Thus the birds become habituated to feeding in the fields and quickly move from insects to corn when it enters the vulnerable milky stage. Experiments in which insect populations in sweet corn crops were treated with insecticides during the week before the grain entered the milky phase, they showed that fewer birds visited these fields and less damage was recorded to the corn in the subsequent vulnerability period than in nearby untreated land. It is probable that the abundance of weeds in cornfields also increases their attractiveness to ichterids and their control would lead to a decrease in the losses produced by these birds.


Chemical sterilization

An alternative way to reduce populations of red-winged blackbird, and therefore the damage they cause to crops, involves implementing a program that is intended to interfere with their ability to reproduce, for example, through the use of sterility (physiology), sterilizing chemicals. Due to the polygynous nature of the species, it has been suggested that such a program could become more effective if directed at males. However, the incidence of promiscuity would imply that chemical sterilization of a certain fraction of males from a local population would not result in a proportional decrease in fertile clutches. The effects of this method would probably vary according to the type of habitat in which the treated males have established their territories. In general, there should be a higher proportion of fertile clutches in those densely populated habitats and with a greater number of renidifications (nest reconstructions). Renidifications are more common in swamps than in the highlands. In turn, individuals that reproduce in the highlands probably feed more often within their own territories than those that reproduce in swamps, which probably makes promiscuity difficult in the first type of habitat. Thus, chemical sterilization could be more effective among upland populations than among swamp populations. Sterilizing chemicals may reduce the number of chicks produced by a successful nest. Since renidification clutches are significantly fewer in number than the original, even if a female that first mated with a sterile male then renidified and mated with a fertile male, perhaps she would produce fewer chicks than she would have had if her first clutch would have been fertile. The number of fertile clutches in a male's territory may be limited through the sterilization of that male, but the degree to which that number decreases will depend on the disposition of the neighboring fertile territorial males and perhaps also on the number of fertile non-territorial males. in the population. Studies with artificial eggs suggest that incubation of sterile eggs would be prolonged, 98 since females normally incubate artificial eggs for around 20 days. An extended incubation of unviable eggs would result in fewer renidification attempts and, therefore, it decreased the opportunities to find a fertile mate for a female who originally mated with a sterile male.


Relationship with humans

Farmers have been known to use pesticides—such as parathion—in illegal attempts to control their populations. In the United States, such efforts are illegal because no pesticide can be used on non-target organisms, or for any use not explicitly listed on the pesticide's label. However, the USDA has deliberately poisoned this species in the past: in 2009, the Animal and Plant Health Inspection Service reported poisoning over 950,000 red-winged blackbirds in Texas and Louisiana. This poisoning has been implicated as a potential cause of the decline of the rusty blackbird, a once abundant species that has declined 99% since the 1960s and has been recently listed as Threatened species, Threatened on the IUCN Red List. In the Anishinaabe languages, an indigenous language group spoken throughout much of the bird's northeastern range, this bird's names are diverse. In the Oji-Cree language, the northernmost of the Anishinaabe languages, it is called ''jachakanoob'', while the Ojibwa language spoken in Northwestern Ontario and into Manitoba ranging immediately south of the Oji-Cree's range, the bird is called ''jachakanoo'' (with the cognates ''cahcahkaniw'' (Swampy Cree), ''cahcahkaluw'' (coastal Southern East Cree), ''cahcahkayuw'' (inland Southern East Cree), ''cahcahkayow'' (Plains Cree); the northern Algonquian languages classify the red-winged blackbird as a type of a junco or
grackle Grackles is the common name of any of 11 passerine birds (10 extant and one extinct) native to North and South America. They belong to various genera in the icterid family. In all the species with this name, adult males have black or mostly blac ...
, deriving the bird's name from their word for "spotted" or "marked". In the vast majority of the other Ojibwa language dialects, the bird is called ''memiskondinimaanganeshiinh'', literally meaning "a bird with a very red damn-little shoulder-blade". However, in the Odawa language, an Anishinaabe language in southwestern Ontario and in Michigan, the bird is instead called either ''memeskoniinisi'' ("bird with a red [patch on its wing]") or ''memiskonigwiigaans'' ("[bird with a] wing of small and very red [patch]"). In N'syilxcn (Colville-Okanagan, Interior Salish language) the bird is known as ƛ̓kƛ̓aʕkək. In the Ho-Chunk Language, Hoocąk language they are known as ''cooxją́ aporošucra'', which describes the round red spot on its wing as well as identifying it as a blackbird. In the Great Plains, the Lakota language, another Indigenous language spoken throughout much of the bird's range, the bird is called ''wabloša'' ("wings of red"). Its songs are described in Lakota as ''tōke, mat'ā nī'' ("oh! that I might die"), as ''nakun miyē'' ("...and me"), as ''miš eyā'' ("me too!"), and as ''cap'cehlī'' ("a beaver's running sore").Buechel, Eugene and Manhard, Paul (2002). ''Lakota Dictionary: Lakota-English/ English-Lakota; New Comprehensive Edition''. Lincoln and London: University of Nebraska Press.


Conservation status

It is a species of Least-concern species, least-concern. Being one of the largest and most widely distributed birds in North America, little has been done to protect it from the effects of habitat destruction and urbanization. It can survive in a wide range of environments, many populations manage to overcome the loss of natural habitats. However, red-winged blackbirds thrive in wetland areas and with the destruction of natural wetlands their population is likely to shrink. The species is protected under the Migratory Bird Treaty Act 1918, a formal treaty between the United States and Canada that was later expanded to include Mexico. This law gives them legal protection in the United States, but they can be killed "when they are found preying or about to prey on ornamental trees or trees planted for shade, crops, livestock or wildlife." A study in Illinois indicated that red-winged blackbird populations doubled between 1908 and 1958. It had traditionally reproduced in wetlands, with Ohio primarily inhabiting swamps associated with lakes and rivers. During the 20th century, however, it adapted to man-made habitat changes and now often nests in hayfields, along roads and ditches, and elsewhere in the highlands. Despite its successful adaptation to changes in practices related to land use, populations of red-winged blackbird have reduced the width of its range during the second half of the twentieth century, and Changes in the abundance and adequacy of grasslands have been implicated in this. In Ohio, the red-winged blackbird was negatively affected between 1966 and 1996 by the decrease in hay production, the earlier harvest of hay and the increase in crops planted in furrows, a situation homologous to that suffered by other species of birds from less numerous grasslands. Although the negative effect of the increased efficiency and the diminishing diversity of modern agricultural practices on the populations of red-winged blackbird in this state may be perceived as a positive event by the producers of corn and sunflower, the agricultural practices that have precipitated the numerical decline of this species may have caused more severe repercussions for birds from less common grasslands, such as the upland sandpiper and the Grasshopper sparrow. In the late 1970s, Ohio hosted the highest density of blackbirds during the breeding season among all US states and Canadian provinces, However, between 1966 and 1996, the reproductive populations in this state showed a marked decrease. Decreasing the area under hay other than alfalfa between those same years was likely to reduce the availability of quality nesting habitats. Likewise, corn even though it attracts insects that red-winged blackbirds consume and despite the fact that their grains represent in themselves an energy source and soybeans which do not constitute a food source for the species, which together made up 1966 to 1996, an average of 70% of the cultivated area in Ohio, do not provide adequate nesting habitat. In turn, the large annual fluctuations in the area cultivated with hay, both from one year to the next and within the same year of a certain reproductive season, Similarly, in Ontario between 1974 and 1995, the average size of harems in a given year was positively related to hay production from the previous year, although the percentage variation in the size of harems from one season to the next the following was not linearly related to the annual percentage change in hay production; Hay production declined during this period and the size of the harems decreased from approximately three females per male to 1.6 females. In addition in Ontario, a negative relationship was found between the
North Atlantic Oscillation The North Atlantic Oscillation (NAO) is a weather phenomenon over the North Atlantic Ocean of fluctuations in the difference of atmospheric pressure at sea level (SLP) between the Icelandic Low and the Azores High. Through fluctuations in the ...
Index (NAO) in the six months prior to a certain reproductive season and the size of the harems. If winter mortality contributes to the decrease in the size of the harems, the annual variations in their size should be related to the annual changes in the rates of return of marked territorial males. Variations in the size of harems and male return rates per year were indeed found to be positively correlated. Although not as pronounced, the relationship between male return rates and winter NAO values was similar to that between changes in harem size and NAO. On the other hand, in southwestern Quebec, red-winged blackbird populations doubled between 1966 and 1981, apparently in response to the development of maize production. The increased availability of residual grains in spring and summer. the reproductive season will probably play a fundamental role in the growth of this bird's population. Likewise, in the mid-1990s, the reproductive population of North Dakota which at least between 1994 and 2002 was at the forefront among all the American states and Canadian provinces in terms of population density of this species began to increase rapidly.


Gallery

File:Agelaius phoeniceus by Brian Gratwicke (cropped).jpg, in McLean, Virginia, USA. File:Red-wingedBlackbird-22OCT2016.jpg, In Sacramento County. October 2016. File:Red Wing Blackbird.jpg, Leaving a feeder in suburban St. Louis, MO. File:Agelaius phoeniceus PP.jpg, A red-winged blackbird clutching a Juncaceae, rush in Point Pelee National Park. File:Red-winged Blackbird (Agelaius phoeniceus), Male - Oakville, Ontario 03.jpg, Red-winged blackbird in spring in Oakville, Ontario, Oakville, Ontario.


References


External links

*
Red-winged blackbird
– eNature.com
Florida bird sounds including red-winged blackbird
– Florida Museum of Natural History * {{Authority control Agelaius, red-winged blackbird Birds of North America Nearctic realm fauna Fauna of the San Francisco Bay Area Birds described in 1766, red-winged blackbird Articles containing video clips Taxa named by Carl Linnaeus Extant Pleistocene first appearances