Wilson's Warbler
(Cardellina pusilla)

Overview

Summary

© Tony Battiste
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The Wilson's Warbler is an abundant species of Canada's boreal and alpine forests and wetlands, its range extending across northern Canada and down through the west coast of British Columbia. The Breeding Bird Survey (BBS) indicates that the population has experienced a slight decrease, but the magnitude of that decrease is within levels considered to be similar to the early 1970s. However, the BBS covers only a small portion of the breeding range, and the results are considered to be of medium reliability. Regional populations within several Bird Conservation Regions have shown decreases varying between 40% and 70%. This species has been identified as a priority for conservation and/or stewardship in one or more Bird Conservation Region Strategies in Canada.

Designations

Population status

Population estimate

Distribution maps

• BirdLife International / NatureServe
• North American Breeding Bird Survey (BBS): Relative Abundance and Breeding Distribution (1970-2016)

Migration strategy, occurrence

Responsibility for conservation

General nesting period in Canada

Conservation and management

This species' habitat use on the wintering grounds appears to be flexible, suggesting that factors on the breeding grounds may be influencing the population decreases observed in some areas (Ammon and Gilbert 1999). Degradation and loss of primary riparian breeding habitat are thought to be among the main causes of declines (Ammon and Gilbert 1999). Wilson's Warbler populations have shown sensitivity to temperature increases in old-growth forests, making climate change a possible concern (Betts et al. 2017).

Bird conservation region strategies

Environment and Climate Change Canada and partners have developed Bird Conservation Region Strategies in each of Canada’s Bird Conservation Regions (BCRs). In these strategies, selected species are identified as priorities for one or more of the following reasons:

• conservation concerns (i.e., species vulnerable due to population size, distribution, population trend, abundance, or threats)
• stewardship responsibilities (i.e., species that typify the regional avifauna or have a large proportion of their range or population in the sub-region)
• management concerns (i.e., species that require ongoing management because of their socio-economic importance as game species, or because of their impacts on other species or habitats)
• other concerns (i.e., species deemed a priority by regional experts for other reasons than those listed above or because they are listed as species at risk or concern at the provincial level)

Select any of the sub-regions below to view the BCR strategy for additional details.

References

• Ammon, E.M. and W.M. Gilbert. 1999. Wilson's Warbler (Wilsonia pusilla), The Birds of North America Online (A. Poole, Ed.). Cornell Lab of Ornithology, Ithaca, New York. Ammon, E.M. and W.M. Gilbert. 1999. Wilson's Warbler (Wilsonia pusilla), The Birds of North America Online (A. Poole, Ed.). Cornell Lab of Ornithology, Ithaca, New York. (Link)
• Betts, M.G., B. Phalan, S.K.J. Frey, J.S. Rousseau, and Z. Yang. 2017. Old-growth forests buffer climate-sensitive bird populations from warming. Diversity and Distributions 00:1–9. Betts, M.G., B. Phalan, S.K.J. Frey, J.S. Rousseau, and Z. Yang. 2017. Old-growth forests buffer climate-sensitive bird populations from warming. Diversity and Distributions 00:1–9. (Link)