Wilson's WarblerCardellina pusilla

adult male, Pacific
Glenn Bartley/VIREO
adult female, Pacific
Joe Fuhrman/VIREO
juvenile, Pacific
Brian E. Small/VIREO
adult male, Eastern
Garth McElroy/VIREO
adult female, Eastern
Claude Nadeau/VIREO
juvenile, Eastern
Barth Schorre/VIREO
adult female, Pacific
Brian E. Small/VIREO

Family

Description

A small and spritely warbler that moves actively in bushes and trees, often flipping its longish tail about as it hops from branch to branch. Typically stays low in semi-open areas, avoiding the interior of dense forest. Although it nests from coast to coast across Canada, Wilson's Warbler is far more common farther west. In the East it is seen in small numbers, but in the Rockies and westward it is often the most abundant migrant in late spring.

Habitat

Thickets along wooded streams, moist tangles, low shrubs, willows, alders. Breeds as far north as timberline, in thickets, second-growth, bogs, or in alder and willow groves near streams and ponds. In migration and winter, occurs from hot lowland thickets up to cool mountain woods; always in scrubby overgrown clearings and thin woods, not in the interior of dense forest.

Feeding Diet

Mostly insects. Presumably feeds mostly on insects, like other warblers. Frequent items in diet include bees, wasps, beetles, caterpillars, and aphids. Also eats some spiders, and sometimes berries. In winter in the tropics, sometimes feeds on protein corpuscles found at the bases of leaves of Cecropia trees.

Feeding Behavior

Feeds usually within 10' of ground, searching actively among foliage of bushes. Hops on ground to probe among fallen leaves, and flutters up to take items from the undersides of leaves. Frequently flies out to catch flying insects in mid-air.

Nesting

Populations that nest along Pacific Coast tend to lay fewer eggs and raise fewer offspring per nesting attempt, and males mate with only one female. Populations that nest in high mountains of West tend to lay more eggs per clutch and fledge more young, and some males have more than one mate. Nest: Usually on ground, sunken in moss or sedges, often at base of shrub. Along Pacific Coast, nests often placed up to 3' above ground, in shrubs or vines. Nest is bulky open cup, built by female, made of dead leaves, grass, and moss; lined with fine grass and hair. Eggs: 4-6, sometimes 2-7. Creamy white with variable marks of brown. Incubation is by female only, 10-13 days. Cowbirds regularly lay eggs in nests of this species. Young: Fed by both parents; brooded by female only. Young leave the nest about 8-13 days after hatching. Normally 1 brood per year.

Eggs

4-6, sometimes 2-7. Creamy white with variable marks of brown. Incubation is by female only, 10-13 days. Cowbirds regularly lay eggs in nests of this species. Young: Fed by both parents; brooded by female only. Young leave the nest about 8-13 days after hatching. Normally 1 brood per year.

Young

Fed by both parents; brooded by female only. Young leave the nest about 8-13 days after hatching. Normally 1 brood per year.

Conservation

Numbers probably stable. Adaptable in its choice of wintering habitats, probably not threatened by cutting of forests in the tropics.

Range

Birds wintering in Mexico apparently migrate around west side of Gulf of Mexico, not across it. In the West, those nesting along the Pacific Coast arrive earlier in spring than those nesting in the mountains of the interior.

Listen

songs #1
alarm chips
songs #3
songs #6
songs #4

Similar Species

adult male, Interior West, breeding

Yellow Warbler

The bright, sweet song of the Yellow Warbler is a familiar sound in streamside willows and woodland edges. This is one of our most widely distributed warblers, nesting from the Arctic Circle to Mexico, with closely related forms along tropical coastlines. Their open, cuplike nests are easy to find, and cowbirds often lay eggs in them. Yellow Warblers in some areas thwart these parasites by building a new floor over the cowbird eggs and laying a new clutch of their own.

adult male

Kentucky Warbler

During spring and summer, the fast, rolling song of the Kentucky Warbler comes from the undergrowth of eastern forests. This bird spends most of its time on the ground in moist, leafy woodlands, walking on the leaf-litter under thickets as it searches for insects. Despite its bright colors, it can be surprisingly hard to see in the shadows of the deep forest interior.

adult male

Prothonotary Warbler

In southeastern swamps in summer, this bright golden warbler sings from high in the trees. It is unique among eastern warblers in its habit of nesting in holes in trees, rather than in the open; it will sometimes nest in birdhouses placed close to the water. The name "Prothonotary" originally referred to a group of official scribes in the Catholic Church who wore bright yellow hoods, as this bird appears to do.

adult male (breeding)

Blue-winged Warbler

The simple buzzy song of the Blue-winged Warbler is often heard in brushy overgrown fields and thickets in the East during the summer. Although the bird is not especially shy, it can be a challenge to observe as it forages actively in the dense brush. In recent decades this species has been expanding its range northward, encroaching on the territory of its close relative, the Golden-winged Warbler. The two species often interbreed.

adult male, breeding

Canada Warbler

Known by its necklace of short stripes, the Canada Warbler is a summer resident of moist, shady woods in the East. It usually stays in the understory, feeding in the bushes or on the ground. Sometimes hard to see in this dense cover, it is not especially shy, and a patient observer can usually get good looks. Although it does breed in Canada, it also nests in the higher Appalachians as far south as Georgia.

adult male

Hooded Warbler

In the forest undergrowth, this skulking warbler seems to call attention to itself by frequently fanning its tail quickly open and shut, flashing the white outer tail feathers. Hooded Warblers are common in moist leafy woodlands of the Southeast. They usually stay low in the shadowy understory, foraging actively in the bushes and nesting close to the ground, although males will move up into the trees to sing.

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