Keywords Birds

Most Canadian breeding species belong to genus Dendroica. Kirtland's warbler, until recently thought to breed only in a restricted area of Michigan, is now believed to have nested in Ontario and possibly Québec. Two other widespread genera of several species are Vermivora and Oporornis, the latter known as "skulkers" of low brush.

The creeperlike black-and-white warbler (Mniotilta varia), the black-masked, marsh-dwelling common yellowthroat (Geothlypis trichas), the flycatching American redstart (Setophaga ruticilla), the thrushlike, ground-dwelling ovenbird, the northern waterthrush (Seiurus noveboracensis) and 2 species of Wilsonia are also widespread.

More restricted breeders include several Dendroica species: Louisiana waterthrush (Seiurus motacilla) and prothonotary, hooded warblers (Wilsonia citrina) and probably Kentucky warblers (Oporornis formosis), both of southern Ontario, northern parula of southern Manitoba east through the Maritimes, yellow-breasted chat (Icteria virens) of southern Ontario and local valleys of southern BC, Alberta and Saskatchewan.

Many warblers have bright yellow plumage which gives them the colloquial name wild canary, a term also applied to American goldfinches (Carduelis tristis). In spring males are usually brightly coloured; females have duller plumages, as do males in fall. Warblers are mostly small, active birds. Their sharp, pointed bills are ideal for probing for insect prey, though some species also catch insects by aerial pursuit. Flycatchers usually have flatter bills with bristles at the base.

Exceptions to the usual cup-shaped nests in shrubs and forks of trees include the dome-shaped ground nest of the ovenbird (Seiurus aurocapillus); the hanging, lichen-based nest of the northern parula (Parula americana); and the hole nest of the prothonotary warbler (Protonotaria citrea), the only species that uses artificial nest boxes.

The brown-headed cowbird (Molothrus ater), a significant brood parasite of several species, poses a significant threat to the rare Kirtland's warbler (Dendroica kirtlandii). Several species have evolved mechanisms which reduce cowbird parasitism, eg, the well-known habit of the yellow warbler (D. petechia) of building new nests on top of old.

Declines in several warbler species have prompted a marked increase in research on migratory bird species on their wintering areas in South and Central America.

Warblers' insectivorous diets make them economically important to humans, especially species that help to control spruce budworm.

Warbler, Kirtland's
Kirtland's warbler is an endangered species that once bred in SW Ontario (artwork by Heather Caldwell). Sound of Kirtland's warbler (press the Sound button) courtesy Monty Brigham, Bird Sounds of Canada.

Warbler, Yellow
The yellow warbler is also called the wild canarie for its yellow plumage (photo by Brian M. Wolitski).

Author MARTIN K. MCNICHOLL

Suggested Reading
H.H. Harrison, Wood Warblers' World (1984); D.H. Morse, American Warblers: An Ecological and Behavioural Perspective (1989).

Links to Other Sites
Endangered Species in Endangered Spaces
An informative website about rare and endangered plants and animals in the Thompson-Okanagan region of British Columbia. Click on the menu at the left side of the page for information about specific species. From the Royal British Columbia Musuem.

Canadian Biodiversity Website
A great information source for all budding biologists. Learn about biodiversity theory, natural history, and conservation issues. From McGill’s Redpath Museum.

Species at Risk Public Registry
A searchable database of Canadian species at risk. Provides illustrated natural histories of each species as well as information about recovery programs, a glossary, and more. From Environment Canada.

Bird Studies Canada
The website for “Bird Studies Canada,” an organization dedicated to preserving wild birds and their habitats. Offers details about species at risk and studies on current threats to avian biodiversity.