Migratory Status: Neotropical migrant
PIF Population Estimate: 
3 200 000
Percent of western hemisphere population breeding in boreal forest: 83%
BAM Effective Detection Radius (m) : 47.96
PIF Maximum Detection Distance (m) : 80
Canadian BBS Population trend: 0.2 n.s. (-2.2 to 2.6)
Life History
The male Cape May Warbler has a striking appearance which can be easily distinguished from other members of the wood warbler family in North America by the distinct yellow breast with black streaks, yellow rump, broad white wing patches and chestnut ear patches.
The breeding range of the Cape May Warbler extends over most of the southern boreal forest, from the Maritime Provinces to east-central British Columbia and in the southern Mackenzie District. Unlike many other species within the genus Dendroica, the Cape May Warbler breeds almost exclusively within the boreal forest region. The winter range includes most of the larger islands in the Greater Antilles (Caribbean), east to Puerto Rico and the Virgin Islands. The species also winters, albeit at a much lower density, along the Caribbean coast of southern Mexico and Central America.
Amongst North American wood warblers, the Cape May Warbler is regarded as the true spruce budworm (Choristoneura fumiferana) specialist. It is known for its ability to track highly irruptive outbreaks, often resulting in large population fluctuations during major outbreaks. Unlike similar species, the Cape May Warbler has evolved a number of strategies to maximize benefits from these outbreaks. During spring migration, birds travel north to eastern Canada before moving west to breeding sites throughout the boreal forest, possibly as a means of locating new budworm outbreaks. Secondly, they are capable of larger and more variable clutch sizes than similar wood warblers, suggesting that the species can increase reproductive output during large outbreaks. This may be important for the population persistence of the species.
As with other, similar species that share the same habitat niche, the song of the Cape May Warbler is high and thin, often at the upper range of most observers hearing. The song of the Cape May Warbler consists of four or more high, thin “seet” notes uttered in rapid succession. Males typically sing conspicuously from the tip of the exposed crown in the tallest conifer trees.
Reference(s)
Baltz, M. E., and S. C. Latta. 1998. Cape May Warbler (Dendroica tigrina), The Birds of North America, No. 332. A. Poole and F. Gill, eds. The Academy of Natural Sciences, Philadelphia, PA, and The American Ornithologists's Union, Washington, D.C.
