Cape May Warbler

Appearance

This bird is a small passerine and is a mid-sized New World warbler. Length can vary from 12 to 14 cm (4.7 to 5.5 in), wingspan is 19–22 cm (7.5–8.7 in), and body mass can range from 9 to 17.3 g (0.32 to 0.61 oz). Among standard measurements, the wing chord is 6.1 to 7.3 cm (2.4 to 2.9 in), the tail is 4.3 to 5 cm (1.7 to 2.0 in), the bill is 0.9 to 1.2 cm (0.35 to 0.47 in) and the tarsus is 1.7 to 1.9 cm (0.67 to 0.75 in). The summer male Cape May warbler has a brown back, yellowish rump and dark brown crown. The underparts are yellow, streaked black, giving rise to the bird's scientific name. The throat and nape are bright yellow and the face is striking chestnut with a black eyestripe. There is a narrow white wing bar.

Other plumages resemble washed-out versions of the alternate-plumaged male's, lacking the strong head pattern. The yellowish rump and at least indications of the white wing bar are always present.

Behavior

This species is insectivorous and lays larger clutches in years when spruce budworm is abundant. It picks insects from the tips of conifer branches or flies out to catch insects. The Cape May warbler also feeds on berry juice and nectar in winter, and has, uniquely for a warbler, a tubular tongue to facilitate this behavior.

The breeding habitat of this bird is the edges of coniferous woodland. Cape May warblers nest in dense foliage near the trunk of the tree, commonly a black spruce, and lay 4–9 eggs in a cup nest. This species can lay the largest clutch of any New World warbler, probably in response to increases in the numbers of spruce budworm during outbreaks.