Birds in Forested Landscapes
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Canada Warbler (Wilsonia canadensis)
Distribution

Breeding: Breeds in a belt of boreal and northern hardwood forests from southeastern Yukon, northeastern British Columbia, and northernCanada Warbler range map Alberta across southern Canada to Nova Scotia, and south to central Minnesota, the Great Lakes region, New York and New England. Range extends south at higher elevations through northern New Jersey and Pennsylvania to the southern Appalachians.

 

Canada Warbler pair by James Coe

 

Winter: Almost exclusively northern South America, east of the crest of the Andes, including Venezuela, Colombia, eastern Ecuador, eastern Peru, and extreme northern Brazil.

Breeding habitat

Coniferous and mixed northern hardwood forests with dense (usually wet) undergrowth; includes aspen-poplar stands, tamarack and cedar bogs, rhododendron thickets, red maple swamps, and deciduous second growth. Appears to prefer limited ground cover, but high foliage density in the shrub layer. Limited to forested wetlands in Rhode Island and hemlock dominated ravines in Ohio.

Conservation status

This warbler is of high conservation importance, because of its low overall density, rapid deforestation in its tropical wintering grounds, and widespread population declines on the breeding grounds. An overall decline of 40% has been noted since 1966, with particularly steep drops in the spruce-hardwood forest region of eastern Canada, Maine, and the Adirondack Mountains. Although it seems tolerant of moderate disturbance, including silvicultural practices favoring regeneration of shrubs, this species’ sensitivity to forest fragmentation and habitat alteration is poorly known in much of its range.

Description

Male: A moderately long-tailed warbler with a distinctive black necklace across the yellow throat and breast. Upperparts areslate gray with a blacker crown and cheek contrasting with a yellow supraloral line and a bold, whitish eye-ring. No wing-bars. Undertail coverts are white.

Female: Similar to the adult male, but with a more olive-gray face and crown; necklace is less distinct or lacking.

Juvenile: Brownish on the head and upperparts, paler buffy-brown on the underparts, paler on the belly to the undertail coverts. Obscure buffy wing bars.

Vocalizations

Songs: Primary song is clear, loud, and distinctive; also extremely variable. It consists of one chip note followed by an abrupt, explosive series of short notes that invariably ends with a 3-note phrase, the last one loud and rising in pitch; consecutive notes are rarely on the same pitch. Described as chip chupety swee-ditchety or chip, suey de swee-dictchety.

Calls: A subdued chyup is given by both sexes, also an alarm call consisting of a loud, sharp check or chip.

Foraging strategy

Forages in shrubs and lower tree branches of both coniferous and deciduous trees; occasionally forages on the ground. Most frequently hops along branches, though a variety of foraging techniques are employed, including flycatching, sallying, hover gleaning, foliage gleaning, and ground gleaning.

Diet

Mostly flying insects, including mosquitoes, flies, moths, beetles, also small hairless caterpillars and spiders.

Behavior and displays

  • Typically active and alert; hops and climbs along branches while moving through thick vegetation.
  • Often observed in low vegetation with tail cocked and wings flicked.
  • Exhibits "wing display," an agonistic display in which male faces male opponent with contour feathers sleeked, body held horizontal, and wings lifted horizontally out from body.

Courtship

  • No information.

Nesting

Nest site: Wet, mossy areas within forests, among ferns, stumps, and fallen logs, often in rhododendron thickets in southern part of range. Typically built within a recessed hole of an upturned tree root mass, rotting tree stump, or sphagnum moss hummock, often on slopes, knolls, in earthen banks, or rocky areas. Dense nest site cover appears to be important habitat requirement.

Height: On or just above ground.

Nest: Bulky, loosely constructed cup with exterior made of some combination of grasses, bark strips, dead leaves, plant fibers, plant down, forb stalks, moss, pine needles, and twigs with deciduous leaves woven into outer wall. Lining often contains horse, deer, or other mammal hair, and rootlets, deciduous leaves, and fine grasses.

Eggs: 4–5 brilliant, buffy, or creamy white eggs are slightly glossy, well speckled with dots and small blotches of various shades and tints in a wreath around the larger end.

Incubation period: Only the female incubates, she is considered a "close sitter" as she is difficult to flush. Incubation appears to last 12 days.

Nestling period: Both parents feed nestlings.

Fledgling period: Nestlings probably leave nest at 10 days. Young are unable to fly, but are vocal. Parents continue feeding, a male was observed feeding a fledgling a few days out of nest.

Broods: No information.

Cowbird Parasitism: In suitable localities, regular host of Brown-headed Cowbird.

Notes

  • Although considered socially monogamous, the extent of extra-pair fertilizations unknown. Some evidence exists that birds maintain a pair bond year-round.

 

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