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Eastern Bluebirds Eject Brown-Headed Cowbird Eggs, Brian Peer, Lyndon Hawkins, Edwin Steinke, Patricia Bollinger, Eric Bollinger
Eastern Bluebirds Eject Brown-Headed Cowbird Eggs, Brian Peer, Lyndon Hawkins, Edwin Steinke, Patricia Bollinger, Eric Bollinger
Faculty Research & Creative Activity
The relationship between the Brownheaded Cowbird (Molothrus ater) and its cavitynesting hosts has received little attention because of the assumption that cowbirds rarely parasitize these hosts. We tested the Eastern Bluebird (Sialia sialis), a host that is sometimes heavily parasitized by cowbirds, for egg ejection behavior. Bluebirds ejected 65% of experimentally added cowbird eggs (n = 20), but ejected no experimentally added conspecific eggs (n = 66). This suggests that cowbird parasitism, not conspecific brood parasitism, is the selective pressure responsible for egg ejection in this species. This level of rejection may be conservative because bluebirds nest in dark cavities, …
Eastern Bluebirds Eject Brown-Headed Cowbird Eggs, Brian D. Peer, Lyndon R. Hawkins, Edwin P. Steinke, Patricia Blair Bollinger, Eric K. Bollinger
Eastern Bluebirds Eject Brown-Headed Cowbird Eggs, Brian D. Peer, Lyndon R. Hawkins, Edwin P. Steinke, Patricia Blair Bollinger, Eric K. Bollinger
Faculty Research & Creative Activity
The relationship between the Brownheaded Cowbird (Molothrus ater) and its cavitynesting hosts has received little attention because of the assumption that cowbirds rarely parasitize these hosts. We tested the Eastern Bluebird (Sialia sialis), a host that is sometimes heavily parasitized by cowbirds, for egg ejection behavior. Bluebirds ejected 65% of experimentally added cowbird eggs (n = 20), but ejected no experimentally added conspecific eggs (n = 66). This suggests that cowbird parasitism, not conspecific brood parasitism, is the selective pressure responsible for egg ejection in this species. This level of rejection may be conservative because bluebirds nest in dark cavities, …