The bay-breasted warbler (''Setophaga castanea'') is a small species of songbird in the New World warbler family,

Parulidae 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 one of thirty-four species in the diverse genus ''

Setophaga ''Setophaga'' is a genus of birds of the New World warbler family Parulidae. It contains at least 33 species. The males in breeding plumage are often highly colorful. The ''Setophaga'' warblers are an example of adaptive radiation with the vario ...

.'' Like all songbirds, or

passerines 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 th ...

, the species is classified in the order Passeriformes.

Distribution

Bay-breasted warblers breed in the

boreal Boreal may refer to: Climatology and geography *Boreal (age), the first climatic phase of the Blytt-Sernander sequence of northern Europe, during the Holocene epoch *Boreal climate, a climate characterized by long winters and short, cool to mild ...

spruce-fir forests of eastern and central

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 ...

, as well as the extreme northern

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 ...

. The species winters in the wet lowland forests of northeastern

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

, the

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 ...

, and southern Central America, and may be seen during spring and fall migration across the eastern half of the United States in a variety of vegetative communities. Many individuals cross the Gulf of Mexico on their long-distance migration, although some travel north and south along the Mexican shore.

Diet and behavior

In the breeding season, bay-breasted warblers feed primarily on insects and spiders, especially the

spruce budworm ''Choristoneura'' is a genus of moths in the family Tortricidae. Several species are serious pests of conifers, such as spruce and are known as spruce budworms. Species *'' Choristoneura adumbratanus'' (Walsingham, 1900) *'' Choristoneura afri ...

(''Choristoneura fumiferana''). These are gleaned from vegetation, never caught on the wing. To avoid competition with similar species, bay-breasted warblers concentrate their foraging on the breeding grounds to the interior middle portions of coniferous trees. On wintering grounds in the tropics, fruit forms a majority of the diet. Wintering bay-breasted warblers often form mixed-species flocks with other

neotropical The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In bioge ...

migrants and resident species. These flocks seek food in the forest canopy, and the bay-breasted warbler is often an aggressive member of the unit,

bullying Bullying is the use of force, coercion, hurtful teasing or threat, to abuse, aggressively dominate or intimidate. The behavior is often repeated and habitual. One essential prerequisite is the perception (by the bully or by others) of an imba ...

smaller species from potential food sources. Bay-breasted warbler in Central Park (43472)

Breeding

Nests are typically constructed in the lower portion of a

spruce A spruce is a tree of the genus ''Picea'' (), a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Earth. ''Picea'' is the sole genus in the subfami ...

or fir tree. The nest is cup-shaped and primarily composed of plant material, with spider silk often utilized as well. Average clutch size is 4-7 whitish eggs with dark 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 ...

at birth, with limited down.

Description

Adult males in breeding plumage are primarily grayish above, with two white wing bars, dark streaks on the back, and a creamy neck patch. The face is black, and the crown, throat, and sides are a dark chestnut color. Breeding females are similar in overall pattern to the males, but are paler and duller. In the nonbreeding season, both sexes gain olive-green feathers on the back, nape, and head. The rufous on the flanks is limited and may even fade away entirely in nonbreeding females. The two white wing bars are present in all plumages.

Measurements

Similar species

In breeding plumage, the bay-breasted warbler may be confused with the

chestnut-sided warbler The chestnut-sided warbler (''Setophaga pensylvanica'') is a New World warbler. They breed in eastern North America and in southern Canada westwards to the Canadian Prairies. They also breed in the Great Lakes region and in the eastern United St ...

(''Setophaga pensylvanica''), which has similar chestnut coloration on the sides. Chestnut-sided warblers may be easily differentiated by the extent of the chestnut, which does not reach the throat or crown. Chestnut-sided warblers also have a bright yellow crown, dark mask, and white cheek and throat in breeding plumage. In fall, nonbreeding bay-breasted Warblers may look very similar to the

blackpoll warbler The blackpoll warbler (''Setophaga striata'') is a New World warbler. Breeding males are mostly black and white. They have a prominent black cap, white cheeks and white wing bars. The blackpoll breeds in forests of northern North America, from Ala ...

(''Setophaga striata''). However, blackpoll warblers never have a hint of chestnut coloration on the flanks, and also have yellowish feet, unlike the black feet of the bay-breasted warbler.

Conservation

Although currently classified by the IUCN as

least concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

, bay-breasted warblers, like many songbirds, are facing population declines across their range. A loss of insect prey and global climate change are contributing factors to decline. The global population is estimated to be fewer than 10 million individuals.

Etymology

The genus name ''Setophaga'' is 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 ...

''ses'', "moth", and ', "eating", and the specific ''castanea'' 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 ...

for chestnut-coloured.

References

External links

*
Bay-breasted warbler species account
- Cornell Lab of Ornithology

- USGS Patuxent Bird Identification InfoCenter * * * {{Taxonbar, from=Q27075917 Setophaga Birds of Canada Native birds of the Northeastern United States Birds of the Caribbean Birds described in 1810 Taxa named by Alexander Wilson (ornithologist)