Wilson's warbler (''Cardellina pusilla'') is a small

New World warbler The New World warblers or wood-warblers are a group of small, often colorful, passerine birds that make up the family Parulidae and are restricted to the New World. The family contains 120 species. They are not closely related to Old World warb ...

. It is greenish above and yellow below, with rounded wings and a long, slim tail. The male has a black crown patch; depending on the subspecies, that mark is reduced or absent in the female. It breeds across

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

and south through the western

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, and winters from

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

south through much of

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

. It is a very rare vagrant to western

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

Taxonomy

Wilson's warbler was

formally described A species description is a formal scientific description of a newly encountered species, typically articulated through a scientific publication. Its purpose is to provide a clear description of a new species of organism and explain how it differ ...

in 1811 by the

ornithologist Ornithology, from Ancient Greek ὄρνις (''órnis''), meaning "bird", and -logy from λόγος (''lógos''), meaning "study", is a branch of zoology dedicated to the study of birds. Several aspects of ornithology differ from related discip ...

Alexander Wilson under the

binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...

''Muscicapa pusilla''. The type locality is southern

New Jersey New Jersey is a U.S. state, state located in both the Mid-Atlantic States, Mid-Atlantic and Northeastern United States, Northeastern regions of the United States. Located at the geographic hub of the urban area, heavily urbanized Northeas ...

. The species was moved to the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

'' Wilsonia'' by the

naturalist Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is cal ...

and ornithologist

Charles Lucien Bonaparte Charles Lucien Jules Laurent Bonaparte, 2nd Prince of Canino and Musignano (24 May 1803 – 29 July 1857) was a French naturalist and ornithology, ornithologist, and a nephew of Napoleon. Lucien and his wife had twelve children, including Cardinal ...

in 1838.

Zoologist Zoology ( , ) is the scientific study of animals. Its studies include the structure, embryology, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems. Zoology is one ...

Thomas Nuttall Thomas Nuttall (5 January 1786 – 10 September 1859) was an English botanist and zoologist who lived and worked in America from 1808 until 1841. Nuttall was born in the village of Long Preston, near Settle in the West Riding of Yorkshire a ...

moved it to ''Sylvania'' in 1840, and by 1845, many authors included it in ''Myiodioctes.'' In 1899, the

American Ornithological 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 ...

returned the species to ''Wilsonia.'' The species is currently assigned to the genus ''Cardellina''. The genus name ''Cardellina'' is a diminutive of the Italian dialect ''Cardella'', a name for the

European goldfinch The European goldfinch or simply the goldfinch (''Carduelis carduelis'') is a small passerine bird in the finch Family (biology), family that is native to the Palearctic zone in Europe, northern Africa, and western Asia. It has been introduced t ...

, and the specific epithet ''pusilla'' means "very small". There are three recognized

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

: *''C. p. pusilla'' was described by Alexander Wilson in 1811. *''C. p. pileolata'' was described by German naturalist

Peter Simon Pallas Peter Simon Pallas Fellow of the Royal Society, FRS FRSE (22 September 1741 – 8 September 1811) was a Prussia, Prussian zoologist, botanist, Ethnography, ethnographer, Exploration, explorer, Geography, geographer, Geology, geologist, Natura ...

in 1811. *''C. p. chryseola'' was described by

Robert Ridgway Robert Ridgway (July 2, 1850 – March 25, 1929) was an American ornithologist specializing in systematics. He was appointed in 1880 by Spencer Fullerton Baird, secretary of the Smithsonian Institution, to be the first full-time curator of birds ...

in 1902. The ''chryseola'' subspecies, which nests in northern coastal California to southwestern coastal Canada, has a distinctive orange-tinged yellow forehead. The population of the subspecies has declined sharply in the 21st century because it migrates preferentially to the southern end of the Baja Peninsula in Mexico, where luxury resort and residential developments have replaced the bird's habitat.

Description

Wilson's warbler is a small

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 generally have an anisodactyl arrangement of their ...

, ranging from in length, with a

wingspan The wingspan (or just span) of a bird or an airplane is the distance from one wingtip to the opposite wingtip. For example, the Boeing 777–200 has a wingspan of , and a wandering albatross (''Diomedea exulans'') caught in 1965 had a wingsp ...

of and a mass of . It has a plain green-brown back and yellow underparts. The male has a small black cap. Males of the western race ''C. p. chryseola'' are greener above and brighter than males of the eastern, nominate race. Individuals from Alaska and the west-central portion of the species' range average slightly larger than those found in eastern and Pacific coastal populations. Its

song A song is a musical composition performed by the human voice. The voice often carries the melody (a series of distinct and fixed pitches) using patterns of sound and silence. Songs have a structure, such as the common ABA form, and are usu ...

is a chattering series of loud descending notes. The call is a flat "chuff". Wilson's warbler resembles the

yellow warbler The yellow warbler (''Setophaga petechia'') is a New World warbler species. Yellow warblers are the most widespread species in the diverse genus ''Setophaga'', breeding in almost the whole of North America, the Caribbean, as well as northern So ...

: the latter is readily distinguished by its different shape, yellow wing markings, and yellow tail spots.

Distribution and habitat

The breeding habitat is fairly open

woodland A woodland () is, in the broad sense, land covered with woody plants (trees and shrubs), or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunli ...

with undergrowth or shrubs and thickets in moist areas with streams, ponds, bogs, and wet clearings. Wilson's warbler breeds in northern Canada and the western US; it winters in overgrown clearings and coffee plantations, forest edges, deciduous forests, tropical evergreens, pine-oak forests, mangroves, thorn-scrub,

riparian A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripar ...

gallery forests, brushy fields, and mixed forests . At all seasons, it prefers secondary growth,

habitats, lakes,

montane Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures lapse rate, fall as elevation increases, causing the ecosystem to stratify. This stratification is ...

and boreal forests with overgrown clearcuts. It is a very rare vagrant to Western Europe.

Behavior and ecology

Breeding

Nesting generally begins in early March in west coast populations, and extends into August in the northern range. The female does the majority of the nest building. The

cup nest A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American robin or Eurasian bl ...

is typically constructed of vegetation and lined with grasses and hair. It is often sunken into moss or sedges at the base of shrubs. The clutch varies from 2 to 7

eggs An egg is an organic vessel in which an embryo begins to develop. Egg, EGG or eggs may also refer to: Biology * Egg cell, the female reproductive cell (gamete) in oogamous organisms Food * Eggs as food Places * Egg, Austria * Egg, Switzerland ...

, which are creamy or off-white with fine reddish spots. The young are

altricial Precocial species in birds and mammals are those in which the young are relatively mature and mobile from the moment of birth or hatching. They are normally nidifugous, meaning that they leave the nest shortly after birth or hatching. Altricial ...

. The montane populations generally have a higher clutch size and nest success rate than those on the coast. The eggs hatch at 11–15 days and the young

fledge Fledging is the stage in a flying animal's life between egg, hatching or birth and becoming capable of flight. This term is most frequently applied to birds, but is also used for bats. For altricial birds, those that spend more time in vulnera ...

at 8–13 days; adults care for them for several weeks. Some montane populations are polygamous (one male breeds with multiple females). Wilson's warbler is a frequent host for 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 souther ...

Feeding

Wilson's warbler is an

insectivore file:Common brown robberfly with prey.jpg, A Asilidae, robber fly eating a hoverfly An insectivore is a carnivore, carnivorous animal or plant which eats insects. An alternative term is entomophage, which can also refer to the Entomophagy ...

, feeding primarily on

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

s gleaned from leaves and twigs, or caught by flycatching. Some of these insects include beetles, bees, or caterpillars. Wilson's warbler is an active forager, moving rapidly through shrubs, on the ground, and sometimes in taller trees during the winter. Feeding birds often twitch their tails or flick their wings nervously.Benedict, Audrey DeLella (2008). ''The Naturalist's Guide to the Southern Rockies.'' pp. 431. The observed feeding rate of the male Wilson's warbler was not significantly different between males with or without mates.Gowaty, P.A. (1996). Field studies of parental care in birds: New data focus questions on variation among females. ''Advance in the Study of Behavior, 25''. 477–531. It also eats a few

berries A berry is a small, pulpy, and often edible fruit. Typically, berries are juicy, rounded, brightly colored, sweet, sour or tart, and do not have a stone fruit, stone or pit (fruit), pit although many wikt:pip#Etymology 2, pips or seeds may be p ...

References

External links

Xeno-canto: audio recordings of Wilson's warbler
* *

– Cornell Lab of Ornithology

- USGS Patuxent Bird Identification InfoCenter {{Taxonbar, from=Q27076007

Wilson's warbler Wilson's warbler (''Cardellina pusilla'') is a small New World warbler. It is greenish above and yellow below, with rounded wings and a long, slim tail. The male has a black crown patch; depending on the subspecies, that mark is reduced or absent ...

Birds of North America Native birds of Alaska Birds of Canada Native birds of the Northwestern United States Native birds of the West Coast of the United States

Taxa named by Alexander Wilson (ornithologist) Birds of Central America