Barn Swallows at the Woodland Park Zoo
To better understand populations of barn swallows (Hirundo rustica) that breed in our region the Woodland Park Zoo has been studying nest site fidelity and breeding success of barn swallows that nest on the zoo grounds since 1999. Each breeding season, volunteers and licensed banders – including PSBO volunteers – have banded adult and nestling swallows and monitored nests since the study began.
Belen Garcia and Keith Hobson from the University of Saskatchewan (Saskatoon, Canada) joined the zoo’s efforts in 2011. In addition to banding swallows, the Canadian researchers collected tail feathers and are using stable isotope measurements to identify evidence for different winter areas. They also attached small geolocators to help track the bird’s migration routes. Their research is part of a large project that investigates migratory connectivity of breeding populations of barn swallows in North America; the team is conducting similar research on barn swallows in Ontario.
More than 1300 barn swallows have been banded at the zoo throughout the project, including nestlings, adults, and juveniles. Consistent with previous studies, barn swallows at the zoo exhibit strong nest site fidelity, with nearly 80% of adults returning to the same breeding structures in most years. Breeding success is high, with about 90% of the young fledging in most years.
The birds that received geolocators in Seattle were determined to be wintering in Colombia, while their eastern counterparts (from Ontario) winter in Brazil. The Canadian research team will conclude the Seattle portion of their study during 2014, when they will collect the final transponders and analyze the data. According to Gretchen Albrecht, 2013 will be the last year of banding at the zoo concurrent with the completion of the Canadian study.
The decline of aerial insectivores
Many bird species are declining worldwide, and there has been a significant decline in aerial insectivores in the Northern US and Canada. Factors that may be contributing to their decline include a loss of flying insects due to increased pesticides, loss of habitat, or changes in weather patterns, or humans removing nests from buildings, homes, or other structures.