Cardellina canadensis

Formerly placed in the genus Wilsonia. Phylogenetic analyses of sequences of nuclear and mitochondrial DNA (Lovette et al. 2010) indicate that two species formerly placed in the genus Wilsonia (canadensis and pusilla)and both species formerly placed in the genus Ergaticus (rubra and versicolor) form a clade with Cardellina rubrifrons. The generic name Cardellina has priority for this clade (AOU 2011).

Large breeding range in North America; large population size; many occurrences; apparently has declined over the past several decades, probably as a result of forest maturation/fragmentation and loss of forested wetlands in the breeding range and habitat loss in the nonbreeding range.

Breeding range extends from southeastern Yukon, northeastern British Columbia, and northern Alberta across southern Canada to Nova Scotia, and south to southern Manitoba, northern Minnesota, Great Lakes region, southern Appalachians (to northern Georgia), northern New Jersey, southeastern New York, and southern New England (AOU 1998, Conway 1999).

Range during the boreal winter extends from Venezuela and northern Colombia south to Ecuador, southern Peru, and the Tepui region of northern Brazil, mostly in and east of the Andes, and rarely northward to Central America (AOU 1998, Conway 1999). Birdlife International (2014) estimates a range of 2.1 million square kilometers.

This species is represented by a large number of occurrences (subpopulations). It has an extremely large range and population size (Birdlife International, 2014), suggesting that the minimum number of EOs in this range is easily met

Declines evident in Breeding Bird Survey data may be related to change in forest structure over the past century, combined with loss of forested wetlands (Conway 1999). Forest regeneration of previously farmed lands in the Northeast probably provided optimal habitat (forest with dense understory) in the early and mid-1900s, but continued forest maturation probably eliminated the understory, and habitat became less suitable for the Canada Warbler (Conway 1999). Additionally, a large area of forested wetlands in the Northeast were drained, filled, and developed between 1950 and 1980 (Tiner 1984). Infestations of the hemlock woolly adelgid have degraded or eliminated habitat in some areas. Miller (1999) reported that declines in Rhode Island may be related to the impingement of urban development on heavily forested landscapes. This species appears to be sensitive to forest fragmentation; density and probability of occurrence in a forest decline with forest area (reviewed by Conway 1999).

Loss of wintering habitat in the northern Andes region of South America may have contributed to the decline (Robinson 1997, Faccio et al. 1997). Diamond (1991) projected that from 1985 to 2000, 28 percent of wintering habitat would be lost. Declines in undisturbed breeding habitats in Vermont (Faccio et al. 1997) suggest the problem is more than loss of breeding habitat, unless there is an undiscovered link between the advancement of succession on those monitoring sites and the reported declines.

Regardless of location, habitat loss is a primary concern. No other major threats have been identified.