Meeting Abstract
Avian song can have important impacts on speciation, through its contributions to premating reproductive isolation. However, to my knowledge, the potential effects of avian calls on species barriers have not been as widely studied. Depending on the functions of calls in a species, and how they contribute to fitness, calls could be an important factor in reproductive isolation. An individual’s ability to learn calls and discriminate between con- and heterospecific calls can affect multiple aspects of fitness. These could include mating success, resource acquisition, and territorial defense. Here, we tested two hypotheses about call learning in the black-capped and Carolina chickadee, and their naturally occurring hybrids. The black-capped and Carolina chickadee species distributions overlap, forming a narrow hybrid zone. The two parent species have slightly different versions of the well-known “chick-a-dee” call, which is used throughout the year by both sexes. Evidence suggests the chick-a-dee call has a variety of uses, including recognition on both the individual and species levels. We hypothesized that each species would be biased towards learning conspecific calls; and that hybrids would exhibit reduced ability to learn either parental species’ calls. We hand reared wild-collected chickadee nestlings from hybrid zone populations in a controlled environment. We exposed all birds to playbacks of Carolina and black-capped calls for two months, and then recorded samples of each bird’s calls. To test for learning ability, we compared similarity of each bird’s call to the playbacks. We also measured frequency of species-specific notes in all recorded samples to analyze for any biases towards learning a single specie’s call. Results from this project will provide further insight into the possible effects of avian calls and call learning on pre- and post-zygotic reproductive isolation.
