Bay-breasted Warbler – Profile | Facts | Female | Fall | Range

Bay-breasted Warbler

The Bay-breasted Warbler nests in boreal forests, normally with a spruce element, from southeastern Yukon throughout central Canada to the Northern Great Lakes, New England, and Atlantic Canada.

Bay-breasted Warbler profile

It winters from Costa Rica and Panama to Colombia and Venezuela, migrating for essentially the most half throughout the Gulf of Mexico.

Although it nests uncommonly within the lowlands of northeastern British Columbia, east of the Rocky Mountain crest, it’s no more than an informal customer in the remainder of the province and the northwestern United States.

Bay-breasted Warbler  Distribution

Bay-breasted Warblers breed within the boreal spruce-fir forests of eastern and central Canada, in addition to the acute northern United States.

The species winters within the moist lowland forests of northeastern South America and southern Central America, and could also be seen throughout spring and fall migration throughout the eastern half of the United States in a wide range of vegetative communities.

Many people across the Gulf of Mexico on their long-distance migration, though some travel north and south alongside the Mexican shore.

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Bay-breasted Warbler  Overview

All plumages present greenish upperparts, streaked back, two outstanding white wing bars, and unstreaked underparts. Breeding-plumaged adults are straightforward to establish, with bay crown, higher breast, and flanks; darkish face; and buffy sides to the neck.

Immatures and fall birds are among the many most complicated of all warblers, even with good views. Separation from Blackpoll Warbler could be significantly troublesome. Consult superior area guides for the subtler factors.

This is an attribute warbler of spruce forest in eastern Canada in summer. Its numbers fluctuate from year to year and are prone to improve rapidly throughout inhabitants’ explosions of the spruce budworm or different forest pests.

This species forages fairly slowly in comparison with most warblers, shifting intentionally among the many branches.

The male Bay-breasted Warbler is unmistakable in spring however goes by way of a hanging transformation in fall, changing into a greenish “confusing fall warbler.”

The male Bay-breasted Warbler has a black face with chestnut throat and aspect plumage. Females, fall adults, and immatures are a lot duller and lack robust color patterns. Both sexes have white-wing bars.

Bay-breasted Warblers are likely to forage in the course of timber. They are among the many earliest warblers who emigrate south within the fall. Bay-breasted Warblers breed within the northern spruce forests of Canada.

Populations have been in decline over the previous 20 years. Possible causes are lack of winter habitat and spraying to cut back caterpillars, significantly the bud spruce worm in Canada

Bay-breasted Warbler  Description

A grayish warbler highlighted with wealthy red-brown and creamy buff in the summertime, the Bay-breasted transforms itself within the fall right into a principally green and white warbler with a touch of the bay on the flanks.

Uncommon throughout the migration, these birds are quite a few within the forests of northern Canada, the place they specialize in spruce budworms.

They nest in low-elevation coniferous forests and forage pretty low in dense foliage on the internal part of the tree. In autumn they intently resemble Blackpoll Warblers, regardless of trying so not like them in the summer season.

Adult males in breeding plumage are primarily grayish above, with two white wing bars, darkish streaks on the back, and a creamy neck patch. The face is black, and the crown, throat, and sides are a darkish chestnut color.

Breeding females are comparable in general pattern to the males, however are paler and duller. In the nonbreeding season, each sex acquires olive-green feathers on the back, nape, and head.

The rufous on the flanks is restricted and should even fade away fully in nonbreeding females. The two white wing bars are present in all plumages.

Bay-breasted Warbler  Behavior

In the breeding season, Bay-breasted Warblers feed totally on bugs and spiders, particularly the spruce budworm (Choristoneura fumiferana). These are gleaned from vegetation, by no means caught on the wing.

To keep away from competitors with comparable species, Bay-breasted Warblers focus their foraging on the breeding grounds to the inside center parts of coniferous timber. On wintering grounds within the tropics, fruit varieties a majority of the diet.

Wintering Bay-breasted Warblers usually kind mixed-species flocks with different neotropical migrants and resident species.

These flocks search meals within the forest cover, and the Bay-breasted Warbler is commonly an aggressive member of the unit, bullying smaller species from potential meal sources.

Bay-breasted Warblers feed by hopping and flying around within the internal components of timber and expecting insect prey, which they seize by gleaning and sometimes hovering.

They readily are a part of mixed-species flocks within the nonbreeding season, after they eat more fruit than bugs.

Bay-breasted Warblers are primarily insectivorous, with a big portion of their diet consisting of spruce budworm.

Since spruce budworms make up a big portion of the Bay-breasted Warbler’s diet, the prevalence of spruce budworms straight impacts Bay-breasted Warbler inhabitant’s sizes from year to year.

Cape May, Blackpoll, and Blackburnian Warblers additionally feed on spruce budworms, however at completely different heights inside the cover, serving to cut back competitors for meals.


Woodlands, conifers in summer. Usually breeds in northern coniferous forest, in thick stands of spruce and fir.

Where spruce just isn’t discovered, will nest in deciduous or combined second-growth woods of birches, maples, firs, and pines. In winter within the tropics, happens in forest edge, second growth, and open woodland.

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A small songbird with a fine, pointed bill and fairly long wings and tail.

Bay-breasted Warbler  Color

Breeding males are grayish above with a reddish-brown crown, breast and flanks, black face, and creamy buff underparts and rear cheek.

Breeding females are comparable however lack black masks and have much less bay color.

In the nonbreeding plumage, yellow-green upperparts and whitish underparts, normally with a touch of pinkish-brown on the flanks. All plumages have two robust white wing bars.


Mostly bugs, berries. In breeding season, eats a wide range of bugs, together with beetles, flies, moths, caterpillars, leafhoppers, and grasshoppers; additionally Virginia creeper berries and mulberries.

May eat many spruce budworms when that insect is at epidemic numbers. In winter within the tropics, additionally eats many berries.

Feeding Behavior

Appears more sluggish in foraging than do different Dendroica warblers feeding in the identical spruce forests.

Forages out and in alongside branches, principally at mid-levels in timber. Rarely catches flying bugs in mid-air. In winter within the tropics, joins combined foraging flocks within the forest cover.


4-5, generally 3-7. Off-white, with brown or black marks at the bigger end. Incubated by the feminine, 12-13 days. The Female is consumed in the nest by the male throughout incubation.

Tends to put more eggs in years of spruce budworm outbreaks, when meals are considerable. Rarely parasitized by cowbirds. Young: Both parents feed the nestlings. Young go away the nest 11-12 days after hatching.


Both parents feed the nestlings. Young go away the nest 11-12 days after hatching.

Bay-breasted Warbler  Nesting

Males could not arrive on breeding grounds till early June. The nest site is on a horizontal branch of dense spruce, hemlock, birch, or different tree, 4-40′ above the ground.

The nest is a big, open cup, both loosely constructed or compact, a product of grasses, lichens, roots, mosses, and protruding conifer twigs; lined with bark strips and hair.

Nests are usually constructed within the decrease portion of a spruce or fir tree. The nest is cup-shaped and primarily composed of plant materials, with spider silk usually utilized as effectively.

The average clutch size is 4-7 whitish eggs with darkish spots. The younger are altricial at the beginning, with restricted down.

Find Bay-breasted Warbler

Most bird watchers’ finest probability to see Bay-breasted Warblers will likely be throughout spring or fall migration. In spring, pay attention to the male’s song, which is analogous to songs of Cape May and Black-and-white Warblers.

The species forages at medium heights on the nesting grounds, however, migrants frequent smaller timber and shrubs. In May, migrants could also be quite a few at hotspots within the eastern Great Lakes.

In September, checking warbler flocks from Appalachia to the Atlantic ought to produce a number of, however, they’re typically unusual.


In spring, most apparently transfer north by way of Central America after which fly north throughout the Gulf of Mexico, persevering with to Canada and the Northeast. In fall, evidently strikes south on a broader front. Some could linger fairly late in the fall.

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Bay-breasted Warbler Facts

Bay-breasted Warblers are voracious predators of spruce budworms. One research concluded that they consumed over 13,000 budworms per hectare (about 2.5 acres) in simply 41 days.

The density of nesting Bay-breasted Warblers throughout outbreaks of spruce budworm was very high on historic occasions. One Ontario research in 1946 discovered as many as 230 pairs in simply 247 acres.

Young Bay-breasted Warblers in fall can look similar to Blackpoll Warblers. One surefire technique to distinguish them is by the color of the soles of their feet—bluish-grey in Bay-breasted, yellow in Blackpoll.

Bay-breasted Warblers nest in a lot the identical habitat as Cape May, Blackburnian, and Blackpoll Warblers, which additionally feed on spruce budworm, however the species all forage and nest at completely different heights.

Bay-breasted Warblers place their nests an average of about 16 feet high. Blackpoll Warbler nests are on average 5 feet higher, and Cape May and Blackburnian nests are normally over 40 feet and generally as high as 80 feet.

Adult Bay-breasted Warblers seem to comply with a more westerly migratory route within the fall than first-year birds. More adults migrate west of the Appalachian Mountains than east of them, whereas first-year birds are more frequent east of the mountains and alongside the coast.

In distinction to the more stable populations of different warblers, Bay-breasted Warbler numbers go up and down relying on outbreaks of the spruce budworm.

The birds are considerable throughout infestations, however, decline and even disappear from some areas a number of years later.

An analogous relationship with spruce budworm exists for Tennessee and Cape May Warblers. Blackburnian and Blackpoll Warblers additionally readily eat budworms however aren’t as specialized in their diets.

The oldest recognized Bay-breasted Warbler was a minimum of Four years, 11 months old.


Although presently labeled by the IUCN as Least Concern, Bay-breasted Warblers, like many songbirds, are dealing with inhabitants declines throughout their range.

A lack of insect prey and world local weather change are contributing components to say no. The world’s inhabitants are estimated to be fewer than 10 million people.

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