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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
Eric K. Bollinger
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 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, …
Explanations For The Infrequent Cowbird Parasitism On Common Grackles, Brian D. Peer, Eric K. Bollinger
Explanations For The Infrequent Cowbird Parasitism On Common Grackles, Brian D. Peer, Eric K. Bollinger
Eric K. Bollinger
We determined the factors responsible for the lack of parasitism on Common Grackles (Quiscalus quiscula) by Brown-headed Cowbirds (Molothrus ater). We found no evidence of parasitism on the 401 grackle nests we monitored in east-central Illinois. By the time cowbirds began laying eggs, 88.5% of all grackle nests were beyond the point of successful parasitism. Grackles rejected cowbird eggs more frequently during the prelaying stage of the nesting cycle (38.2%) compared to later stages (12.3%). Thirty-three cowbird eggs and nestlings were cross-fostered into grackle nests. Data were collected on 15 cowbird nestlings, of which three fledged. The cross-fostered cowbird eggs …
Explanations For The Infrequent Cowbird Parasitism On Common Grackles, Brian Peer, Eric Bollinger
Explanations For The Infrequent Cowbird Parasitism On Common Grackles, Brian Peer, Eric Bollinger
Faculty Research & Creative Activity
We determined the factors responsible for the lack of parasitism on Common Grackles (Quiscalus quiscula) by Brown-headed Cowbirds (Molothrus ater). We found no evidence of parasitism on the 401 grackle nests we monitored in east-central Illinois. By the time cowbirds began laying eggs, 88.5% of all grackle nests were beyond the point of successful parasitism. Grackles rejected cowbird eggs more frequently during the prelaying stage of the nesting cycle (38.2%) compared to later stages (12.3%). Thirty-three cowbird eggs and nestlings were cross-fostered into grackle nests. Data were collected on 15 cowbird nestlings, of which three fledged. The cross-fostered cowbird eggs …
Explanations For The Infrequent Cowbird Parasitism On Common Grackles, Brian D. Peer, Eric K. Bollinger
Explanations For The Infrequent Cowbird Parasitism On Common Grackles, Brian D. Peer, Eric K. Bollinger
Faculty Research & Creative Activity
We determined the factors responsible for the lack of parasitism on Common Grackles (Quiscalus quiscula) by Brown-headed Cowbirds (Molothrus ater). We found no evidence of parasitism on the 401 grackle nests we monitored in east-central Illinois. By the time cowbirds began laying eggs, 88.5% of all grackle nests were beyond the point of successful parasitism. Grackles rejected cowbird eggs more frequently during the prelaying stage of the nesting cycle (38.2%) compared to later stages (12.3%). Thirty-three cowbird eggs and nestlings were cross-fostered into grackle nests. Data were collected on 15 cowbird nestlings, of which three fledged. The cross-fostered cowbird eggs …