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Egg Removal By Brown-Headed Cowbirds: A Field Test Of The Host Incubation Efficiency Hypothesis, Douglas R. Wood, Eric K. Bollinger
Egg Removal By Brown-Headed Cowbirds: A Field Test Of The Host Incubation Efficiency Hypothesis, Douglas R. Wood, Eric K. Bollinger
Faculty Research & Creative Activity
Brown-headed Cowbirds (Molothrus ater) often remove host eggs, usually to the detriment of the host's reproductive success. We tested the hypothesis that host egg size and number influence the incubation efficiency of a parasitic egg. A single House Sparrow (Passer domesticus) or Brown-headed Cowbird egg was placed in each host nest (addition), and in some nests a host egg was removed as well (addition/removal). Hatching success and incubation length were measured to determine whether host-egg removal conferred an advantage in incubation efficiency compared to simple addition of a parasitic egg. Redwinged Blackbirds (Agelaius phoeniceus) and Chipping Sparrows (Spizella passerina) served …
Egg Removal By Brown-Headed Cowbirds: A Field Test Of The Host Incubation Efficiency Hypothesis, Douglas Wood, Eric Bollinger
Egg Removal By Brown-Headed Cowbirds: A Field Test Of The Host Incubation Efficiency Hypothesis, Douglas Wood, Eric Bollinger
Faculty Research & Creative Activity
Brown-headed Cowbirds (Molothrus ater) often remove host eggs, usually to the detriment of the host's reproductive success. We tested the hypothesis that host egg size and number influence the incubation efficiency of a parasitic egg. A single House Sparrow (Passer domesticus) or Brown-headed Cowbird egg was placed in each host nest (addition), and in some nests a host egg was removed as well (addition/removal). Hatching success and incubation length were measured to determine whether host-egg removal conferred an advantage in incubation efficiency compared to simple addition of a parasitic egg. Redwinged Blackbirds (Agelaius phoeniceus) and Chipping Sparrows (Spizella passerina) served …
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 …