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Black Swift Wintering Grounds Discovered

Juvenile Black Swift, September. Photo by Brian L. Sullivan.
Juvenile Black Swift, September. Photo by Brian L. Sullivan.

One of the last birds that breeds in the U.S. and Canada with an entirely unknown winter destination has finally given up its secret. After years of research – and with some luck – three Colorado researchers have learned that Black Swifts travel more than 4,000 miles to spend the winter in Brazil. Kim Potter (U.S. Forest Service), Carolyn Gunn (Independent Wildlife Biologist and Veterinarian), and Jason Beason (Rocky Mountain Bird Observatory) have been studying Black Swifts for more than a decade in Colorado and New Mexico. When the team learned of the potential of geolocators for solving the mystery of where Black Swifts spend the winter months, they acted quickly and raised enough funds to purchase four devices to deploy in 2009 in Colorado. In 2010, they were elated to recover three of the four geolocators. All three showed similar migratory pathways and wintering areas! Their manuscript appears in the March 2012 Wilson Journal of Ornithology (Volume 124:1).

The lowland rainforest of western Brazil is the center of the wintering area, which is very intriguing since there are no documented records for Black Swift in Brazil. The researchers had contacted birders and field trip leaders in Brazil prior to publishing their manuscript, and many of the people with experience in Brazil said the same thing: that identifying swifts in this area is extremely problematic because of the difficulty of separating Black Swift from the other Cypseloides swifts that occupy the area. Now at least we know that Black Swifts are indeed wintering in western Brazil. Geolocators are accurate to approximately +/-100 miles, so this research has not been able to pinpoint where they are roosting. To discover specific roost sites in Brazil, satellite tracking devices will be needed, and it will probably be years before those are small enough to be carried by swifts. eBird has great potential to help find specific roosting sites in this area, so we encourage anyone with observations of swifts to report what they have seen (preferably with detailed notes). Anyone seeing all dark Cypseloides swifts in this region can enter their data as such (eBird has categories for Cypseloides sp. and even large swift sp.), and in this case even these imprecise identifications could have great value. Perhaps your records will assist with narrowing down the sites where Black Swifts roost during the winter months!

Citation: The Northern Black Swift: Migration Path and Wintering Area Revealed. Beason, J. P., C. Gunn, K. M. Potter, R. A. Sparks, and J. W. Fox. The Wilson Journal of Ornithology Mar 2012 : Vol. 124, Issue 1, pg(s) 1-8 doi: 10.1676/11-146.1

Contributed by: Jason Beason, Rocky Mountain Bird Observatory, Fort Collins, Colorado.