Using Canadian migration monitoring network data to assess population changes in Canada Warbler (Cardellina canadensis)

Abstract

The Canada Warbler (Cardellina canadensis) has been listed since 2010 as Threatened according to the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) due to significant and long-term declines in the global population. The cause of the decline over the past years cannot be narrowed down to one threat, but loss and degradation of habitat on the breeding and wintering grounds are one of the major threats. Tracking this species is extremely important and a role for bird banding at observatories occurs during migration, for example at the Long Point Bird Observatory in Ontario. Data from this bird observatory was chosen to analyze spring and fall population trends for the Canada warbler using the database in NatureCounts, along with using the two COSEWIC documents, to explore whether threats to this species have changed or have stayed the same since 2010. The COSEWIC reports list the same threats, including habitat loss, vulnerability to highways, forestry practices and pollutants. However, climate change is discussed more in the most recent report. Combined with the fact that since listing, the Canada Warbler population is continuing to decline, I conclude that threats are increasing because of increasing effects of climate change.