Date: 2/24/26 1:51 pm From: ED DEAL via Tweeters <tweeters...> Subject: [Tweeters] Cooper's Hawk predation
Tweets,
For more information on this thorny subject, I recommend reading section 3 of Stan Rullman's 2012 UW PhD Dissertation "Effects of Cooper's Hawk Predation and Presence on Songbird Survivorship, Nesting Success, and Community Structure," In short, Stan compared songbird nesting success in sites with active COHA nests and matched sites without a COHA nest. Songbird productivity was slightly depressed close to a COHA nest while further away from the COHA nest, songbird sucess was significantly lower. He attributed this to the COHA excluding corvids and sciurids from their nest area. This is similar to the study of hummingbird nest productivity in SE Arizona. Hummingbird nests close to COHA or AMGO nests were protected from nest predators. Except in the case of Rullman's study, songbirds suffered some predation as "protection money" from corvids and sciurids. Stan's conclusion was that there was a slight reduction in the abundance of robins.
And the hummingbird reference is "Proximity to Active Accipiter Nests Reduces Nest Predation of Black-chinned Hummingbirds" Greeney & Wethington, Wilson J. Ornith., 121(4):809-812.
