Hybridization occurs when two species interbreed and produce offspring. While we often think of hybridization in animals as something that’s rare, or something that is a reproductive dead end, it is actually fairly common and is an important tool to help us understand how and why species evolved in the first place. In the bird world, it’s estimated that hybridization occurs in 10 percent of all species. Hybrid zones, geographic regions where two species overlap and interbreed, have been particularly important in shaping our understanding of evolution. Billerman’s research has focused on studying hybridization on the Great Plains of North America, where multiple pairs of species hybridize, including Eastern and Spotted Towhees, Indigo and Lazuli Buntings, and Baltimore and Bullock’s Orioles. Using these species as guides, we will explore ways in which hybridization can teach us about biodiversity and the evolution of species.
Shawn Billerman is a Science Editor with the Birds of the World Project at the Cornell Laboratory of Ornithology. In addition to his research on hybridization in birds of the Great Plains, he has also looked at birds of the Pacific Northwest, such as Red-naped and Red-breasted Sapsuckers.