Resembling swallows,, but more closely related to hummingbirds, swifts have unique migratory behavior, roosting for days at a time in chimneys or hollow trees along their migratory route in groups of hundreds or thousands of individuals. Little is known about whether groups that travel and roost together during migration are all from the same wintering site or are made up of individuals from across their winter range. A 2012 mortality event in British Columbia that killed more than 1,300 migrating swifts provided researcher Matthew Reudink, Ph.D., of Thompson Rivers University in Kamloops, British Columbia, and his colleagues with the opportunity to determine where the birds had spent the winter. Their results, published online on October 28, 2015 in an open-access article in The Condor: Ornithological Applications, suggest that the birds in the roost all came from the same two or three wintering sites. Bird breeding populations strongly connected to specific wintering areas may be more vulnerable to population declines, so this has important implications for swift conservation. The new article is titled “"Patterns of Migratory Connectivity in Vaux's Swifts at a Northern Migratory Roost: A Multi-Isotope Approach.” Like many birds that catch insects on the wing, Vaux's swifts (Chaetura vauxi) have experienced significant population declines, and the May 2012 mortality event in Cumberland, British Columbia, may have killed nearly 3% of the province's population. "The circumstances surrounding the event are a bit unclear, but our understanding is that the birds became trapped in a chimney that was in a residence and were unable to escape out of the top," explains Dr. Reudink.
Login Or Register To Read Full Story