IS TIMING EVERYTHING? Examining the importance of parasitism timing to cowbird chick success
Research Advisors: Dr. Jeff Hoover and Dr. Wendy Schelsky
Zoom link: https://go.illinois.edu/DefenseZoomLink
Brood parasitism, a reproductive strategy where a parasitic parent leaves its offspring to be raised by an unrelated host, has resulted in specialized adaptive behaviors on the part of the parasite. The parasite must decide when to parasitize a host, and erring in this decision could have dire fitness consequences, thus resulting in strong selection for specific parasitism timing behaviors. Brown-headed cowbirds are North America’s most widespread avian brood parasite and successfully parasitize 170+ host species, but female cowbirds are cryptic and difficult to monitor, and much of how they make parasitism decisions is not well understood. Despite such diversity in hosts, cowbirds nearly always parasitize during the narrow window of the host’s laying period before the start of incubation, resulting in their offspring hatching before the host’s. How important is this timing to get right, and what are the reproductive costs to parasitizing - and thus hatching - late? I simulated three different parasite timing decisions by adding cowbird eggs to the nests of a common host, the prothonotary warbler, at different stages of the host’s laying and incubation period and monitored the effects on cowbird chick success. I found that late parasitism significantly reduced cowbird chick survival, suggesting that accurate parasitism timing is an essential and potentially strongly selected for behavior.
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