Predator type and relative risk affects the repeatability of nest defense in a songbird

Interindividual differences in nest defense towards a single predator type have been shown to be repeatable in multiple species, supporting the presence of personality. Here, we assessed if the nest defense of female northern house wrens ( Troglodytes aedon ) was repeatable across different types of predators, which is predicted by personality and largely untested. Over three years, we placed a decoy of a common nest predator, the eastern rat snake ( Pantherophis alleghaniensis ), on top of nest boxes and measured female behavior. Each season, we also presented a second stimulus of varying threat level, including an eastern chipmunk decoy ( Tamias striatus ), a taxidermied Cooper’s hawk ( Accipiter cooperii ), and a novel object of unknown threat. We measured repeatability between each pair of threats and compared the population-level response to the snake across years. Nest defense was significantly repeatable between the snake and chipmunk, which presented similar risks. It was also repeatable between the snake and novel object despite the population-level response to the object being significantly weaker. In contrast, nest defense was not repeatable between the snake and the hawk, which posed a significant threat to adult survival that may have disrupted the consistency of the female response. Finally, the average, population-level response to the snake did not detectably differ among years, indicating stability in this behavior despite high turnover in breeding adults. These results suggest the presence of personality in nest defense, but more research is needed to evaluate the effect of high-risk predators on the repeatability of this behavior.