Veery migration and winter ecology
How light-level geolocators provided researchers with revolutionary new insights into the migration and winter ecology of the Veery.
Published: October 21, 2011
In recent years, light-level geolocators have given us revolutionary new insights into the movements of Purple Martin, Sooty Shearwater, European Hoopoe, and many other long-distance migrants. Now researchers have used the device to revise completely our assumptions about the winter ecology of the Veery.
Geolocators are small, lightweight devices that birds wear like a backpack. The machines use light sensors, data loggers, and time stamping to calculate latitude and longitude.
Wildlife ecologist Christopher M. Heckscher and colleagues from Delaware State University and the British Antarctic Survey attached geolocators to 24 Veeries in Delaware in June 2009. When the birds returned the following year, the researchers recaptured five, removed the trackers, and analyzed the data.
What was learned was astonishing: The time the thrushes spent on their winter grounds in Brazil, nearly six months, was longer than previously thought, their spring migration was much quicker, and they not only migrated from Delaware to South America but made a within-season migration to a second winter site.
“Our discovery of multiple wintering sites,” writes Heckscher, “is the first report of individuals of a North American-breeding Neotropical migrant songbird showing prolonged occupation of two widely separated regions between autumn and spring migration.”
Heckscher suggests that Veeries settle first in lowland forests that flood seasonally, then relocate to higher elevations or other regions that remain dry, as resident lowland birds in Amazonia do.
Each Veery arrived at its initial winter site in November and migrated to its second winter site between January 7 and March 7.
The Veeries began their return migrations in mid-April, flew an average of 287 kilometers a day (178 miles), and completed their journey in as little as 17 days, arriving in Delaware between April 29 and May 20.