A long line of accomplished raptor biologists have studied this amazing hawk, especially in the Butte Valley of northwestern California. Brian Woodbridge, Peter Bloom, Mike Callopy, Chris Briggs, and Chris Vennum have each played pivotal roles in understanding this species, from unraveling details of their breeding ecology and polymorphism, to discovering their wintering grounds in Argentina and relentlessly advocating for their protection from insecticide poisoning. You can read more about this incredible story, and the inspiring group of biologists' ongoing work in an All About Birds article and at Tracking Talons.
Lab member Lizzi Meisman is a recent addition to this team, and her research is building on the shoulders of those who came before her, drawing on over 40 years of data to ask a question aligned with our lab's core themes of habitat selection and habitat quality -- do the hawks' nest site preferences lead them to higher reproductive success? This idea is called the "adaptive breeding habitat selection hypothesis," and the Butte Valley Swainson's Hawk dataset provides a powerful opportunity to test it in raptors. The landscape has changed over the decades with agricultural conversion while the hawk population has increased, prompting questions about how intraspecific competition may also affect reproductive success (density dependence).
We're also interested in tracking these birds using state-of-the-art GPS tags to examine how they may or may not respond to human disturbance and anthropogenic noise. In this case, lab member Ayla Zolwik is working with CalTrans, California's High Speed Rail Authority, and Pete Bloom to study how nesting Swainson's Hawks behave under various level of noise and construction activity associated with the rail line. This work is based out of Visalia, California.