American Kestrels are North America’s most plentiful falcon, guarding cityscape ledges or hovering over rural roadsides to hunt rodents and insects. This small falcon is familiar even to casual observers, but a look at population levels reveals a perplexing mystery: continent-wide, kestrels have declined by nearly half since the 1960s.
The American Kestrel ranges from the Yukon to Tierra del Fuego, so compiling a “snapshot” of kestrel life requires a veritable army of observers. Fortunately, kestrels are cavity-nesters and readily inhabit nest boxes during the breeding season, making observation relatively simple so that virtually anyone can contribute data to our continent-wide study. “Citizen scientists” are the eyes, ears, and hearts of the American Kestrel Partnership, contributing countless hours and enthusiasm and creating an international community throughout the Americas to unite people based on love for their backyard falcon.
Threats to American Kestrels
Although many local nest box programs exist, the American Kestrel Partnership is the only coordinator of an international network of professional and citizen scientists, managing a single database to look for far-reaching trends that could explain population declines.
Now with more than five years of data, we have narrowed our inquiry to go beyond simple “head counts” and delve into questions about the kestrel’s life cycle. Are adults returning after winter to breed? Are they dying at high rates during breeding, migration, or over-wintering? Are they breeding less often, or failing when they do breed? And, critically, how are they affected by land use, contaminants, climate, predators, and other species? To find answers, our colleagues at Boise State University and UCLA are conducting genetic analyses using feather samples gathered by our partners throughout North and South America.
We’ve also discovered that in nest box studies, just as in real estate, location is key.
Nest boxes are not the “golden ticket” to halting population declines, and could even harm wildlife if placed incorrectly. These findings reinforce our focus on responsible nest box placement and standardized, consistent monitoring to ensure that American Kestrel boxes are placed in safe locations.