The role of avian song in speciation is widely studied, but how avian calls contribute to speciation remains largely unknown. Although song is typically used only by males for reproductive purposes, calls are used by both sexes, across most species, and throughout the year. Calls are assumed to be innate, but some species learn calls and adjust acoustic characteristics based on experience. The contexts in which calls occur are important for fitness, including species recognition, foraging, and defending territories. Therefore, in sympatry, multiple aspects of fitness could be affected by the ability of an individual to learn calls and discriminate between con- and heterospecific calls. We used the black-capped and Carolina chickadee and their naturally occurring hybrids to test two hypotheses about call learning. The black-capped and Carolina chickadee both use similar versions of the well-known “chick-a-dee” call. The chick-a-dee call has a variety of uses, including both individual- and species-level recognition. We hypothesized that each species would be biased towards learning conspecific calls; and that hybrids would exhibit reduced ability to learn either of the parental species’ calls. We hand reared wild-caught 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 each of the bird’s calls. To test for biases towards learning one species’ call over the other, we measured the frequency of species-specific notes in all recorded calls. To test for the relative call learning ability of parental species versus hybrids, we compared the similarity of each bird’s call to the playbacks. Results from this project will provide insight into the potential for avian calls and call learning to contribute to pre- and post-zygotic reproductive isolation.