Scientific Name: Wilsonia canadensis
Nest Type: Cup
Nest Location: Ground; 0-0.5'
Clutch Size: 3-5; avg. 4
Food: Insects
Foraging Guild: Hover and glean, foliage and ground gleaner
The Canada Warbler spends the winter in South America (Peterson 1980) and is a summer breeding resident primarily in north central and northeastern Minnesota
(Janssen 1987). The breeding distribution of the species in North America is primarily the northeast and north central United States, the Appalachians, and southern
Canada, excluding the western portion (Peterson 1980). It is an uncommon spring migrant in Minnesota, arriving in early May through early June (Janssen 1987).
Fall migration begins in mid-August and continues through early October (Janssen 1987).
The Canada Warbler occupies dense wooded areas with a well-developed shrub layer (Harrison 1975). The species prefers mesic deciduous, wet mixed, and mesic
mixed forest including northern hardwoods, white pine, balsam fir, hemlock, and cedar. Within these habitats, the species prefers deciduous thickets, usually in
association with open water, such as small creeks (Roberts 1932). It occasionally occurs in shrub wetlands of alder adjacent to permanent bodies of water (Brewer
et al. 1991). In northern Minnesota, the species was observed primarily in mature stands in the Chippewa National Forest in 1991. Highest density was in upland
spruce stands (about 3 pairs/40 acres) (Hanowski and Niemi 1991a). The species occupied a wider range of habitats in the Superior National Forest including
lowland conifer, pine forests, deciduous forests, and upland spruce forests. Highest densities in the Superior National Forest were recorded in lowland conifer and
mature aspen (about 2 pairs/40 acres) (Hanowski and Niemi 1991b).
Most individuals were observed in mature stands in northern Minnesota in 1991. This suggests that a well-developed shrub layer, often in association with small
creeks and streams, under a canopy of mature trees is their preferred breeding habitat (Hanowski and Niemi 1991a, Hanowski and Niemi 1991b).
The Canada Warbler places its nest on or near the ground, in a cavity or bank, in roots, on ledges, or in hummocks (Roberts 1932, Harrison 1975). Four eggs is the
typical clutch size for the species (Harrison 1975). Canada Warblers are foliage gleaners, primarily insectivorous, and use both conifer and deciduous substrates
(Morse 1989).
The status of the Canada Warbler in Minnesota is unclear because it has not occurred in high enough abundance over the past 23 years on the Breeding Bird
Surveys to detect trends (Janssen 1990). Sauer and Droege (1992), however, noted a short term decrease of about 2% per year from 1978 to 1988 based on 340
roadside counts gathered in the eastern United States. In addition, the species seems to require large expanses of forest area and, therefore, may be susceptible to
forest fragmentation (Finch 1991). Finch (1991) reports that it was found in isolated forest areas that were larger than 470 acres. Robbins et al. (1989) reported
that the species requires areas of 1250 acres for breeding. However, there is no evidence of area sensitivity in Minnesota because no studies have been published to
date.
