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Bay-breasted Warbler


IUCN Conservation Status: Least Concern

A large warbler of the northern spruce forests, the Bay-breasted Warbler benefits from spruce budworm outbreaks when the caterpillars provide abundant food. Spraying to control the destructive outbreaks may have reduced populations of this warbler.

At a GlanceHelp

Both Sexes
5.5 in
14 cm
7.9–8.7 in
20–22 cm
0.4–0.6 oz
10–17 g
Other Names
  • Paruline à poitrine baie, Fauvette à poitrine baie (French)
  • Reinita pecho bayo, Reinita castaña (Spanish)

Cool Facts

  • The Bay-breasted Warbler is closely related to the Blackpoll Warbler, and hybrids between the two species are known. The Bay-breasted Warbler is known to hybridize also with Yellow-rumped and Blackburnian warblers.
  • Adult Bay-breasted Warblers appear to follow a more western migratory route south in the fall than first-year birds. More adults migrate west of the Appalachian Mountains than east of them, while first-year birds are frequent along the coast.
  • In contrast to the more stable populations of other warblers, Bay-breasted Warbler numbers go up and down depending on outbreaks of the spruce budworm. It is abundant during infestations, but declines or even disappears from some areas a few years later.



Breeds in boreal spruce and fir forest. Winters in lowland tropical forest and second growth.



Insects and spiders, fruit in winter.


Nesting Facts
Clutch Size
4–7 eggs
Egg Description
White or creamy with bold dark spots.
Condition at Hatching
Helpless with sparse brown down.
Nest Description

Nest an open cup of twigs, bark, lichen, spider web, and plant down; lined with fine rootlets, pine needles, hair, moss, and fine grasses. Placed on limb of dense spruce tree.

Nest Placement



Foliage Gleaner

Gleans insects off leaves and branches in middle part of trees.


status via IUCN

Least Concern

Populations decreasing over last 20 years, possibly as result of spraying for spruce budworms. Loss of wintering habitat may be a problem.


    1. Dunn, J. L., and Garrett, K. L. 1997. A Field Guide to Warblers of North America. Houghton Mifflin Co., Boston.
    2. Williams, J. M. 1996. Bay-breasted Warbler (Dendroica castanea). In The Birds of North America, No. 206 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, PA, and The American Ornithologists' Union, Washington, D.C.

Range Map Help

Bay-breasted Warbler Range Map
View dynamic map of eBird sightings

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