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. They are not closely related to Old World warblers or Australian warblers. Most ...

. 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 ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

and south through the western

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

, and winters from

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

south through much of

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

. It is a very rare vagrant to western

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

Taxonomy

Wilson's warbler was formally described in 1811 by the

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 ...

Alexander Wilson under the

binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

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

New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...

. The species was moved to 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 ...

'' Wilsonia'' by the naturalist 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 ornithologist. Lucien and his wife had twelve children, including Cardinal Lucien Bonaparte. Life and career ...

in 1838.

Zoologist Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the Animal, animal kingdom, including the anatomy, structure, embryology, evolution, Biological clas ...

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

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 m ...

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 that is native to Europe, North Africa and western and central Asia. It has been introduced to other areas, including Austral ...

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

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

: *''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 Prussian zoologist and botanist who worked in Russia between 1767 and 1810. Life and work Peter Simon Pallas was born in Berlin, the son ...

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 bird ...

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 are distinguished from other orders of birds by t ...

, 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 other wingtip. For example, the Boeing 777–200 has a wingspan of , and a wandering albatross (''Diomedea exulans'') caught in 1965 had a wingspan of ...

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 intended to be performed by the human voice. This is often done at distinct and fixed pitches (melodies) using patterns of sound and silence. Songs contain various forms, such as those including the repetitio ...

is a chattering series of loud descending notes. The call is a flat "chuff". The 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, and down to northern S ...

: 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 trees, 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 sunlight and limited shade (see ...

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. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks ar ...

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 fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial f ...

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 Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

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

altricial In biology, altricial species are those in which the young are underdeveloped at the time of birth, but with the aid of their parents mature after birth. Precocial species are those in which the young are relatively mature and mobile from the mome ...

. 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 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 vulnerable c ...

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 southern ...

Feeding

Wilson's warbler is an

insectivore A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores wer ...

, feeding primarily on

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...

gleaned Gleaning is the act of collecting leftover crops from farmers' fields after they have been commercially harvested or on fields where it is not economically profitable to harvest. It is a practice described in the Hebrew Bible that became a legall ...

from leaves and twigs, or caught by flycatching. Some of these insects include beetles, bees, or caterpillars. The 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 or pit, although many pips or seeds may be present. Common examples are strawberries, raspb ...

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