A ubiquitous life-history trade off is between current and future reproduction, which is mediated by parental survival. Bird species with large investments in current reproduction (large clutch sizes) have lower future reproductive potential due to their decreased adult survival, compared to species with small clutch sizes. Consistent with these life history strategies, parental behavior in response to predators also differs such that species with large clutch sizes respond more to predators of nestlings, while species with small clutch sizes respond more to predators of adults. We hypothesized that the same behavioral differences exist within a population whereby individuals that exert greater parental effort prioritize the safety of their nestlings over that of their own, and individuals that exert lower parental effort prioritize their own safety over that of their nestlings. We tested this hypothesis by determining how Carolina chickadees (Poecile carolinensis) respond to predator models after their parental effort had been experimentally altered through a clutch size manipulation. We monitored 100 bird boxes fitted specifically for Carolina chickadees during spring 2017. Paired nests were randomly allocated between increased and decreased clutch size treatments. Clutch sizes were manipulated so that some had two fewer while others had two more eggs than the adult initially laid. Nests were then randomly allocated between three predatory treatments: adult predator, nestling predator, and a non-predatory control. Feeding rate of 8 day old nestlings was recorded for one hour immediately before, and immediately after, the placement of the predatory model near each nest. The change in feeding rate was calculated in response to the predator models. We predict that adults with increased clutch sizes will decrease their feeding rate most in response to a nestling predator, while adults with decreased clutch sizes will decrease their feeding rate most in response to adult predators.


Our greatest thanks goes to the various land owners who allowed us to install bird boxes on their properties, including Young Harris College, Brasstown Valley Resort & Spa, Brasstown Valley Golf Course, U.S. Forest Service and many others. We could not have accomplished this without the continued support of the faculty, students and staff at Young Harris College. We are also deeply grateful to the funding recieved from the Young Harris College Undergraduate Research Fund and the Highlands Plateau Audubon Society.

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