Chickadees can smell – a new study out of Lehigh University, the first to document naturally hybridizing songbirds’ inclination for the scent of their species.
Amber Rice, an evolutionary biologist at Lehigh, studies natural hybridization-when separate species come into contact and mate-to better learn how species originate and how to present species are maintained. The two species that make up the hybridized population she studies are the black-capped chickadee and its relative the Carolina chickadee.
Rice and Ph.D. student, Alex Van Huynh, set out to test the potential for the scent to behave as an alternative mate cue, contributing to reproductive isolation between the black-capped and Carolina chickadees who live within the “hybrid zone” within the eastern Pennsylvania area where Lehigh is located.
Huynh and Rice found that both black-capped and Carolina chickadees produce chemically distinct pure oils. Testing each male and females of each chickadee species, they found that males and females choose the scent of their species over the odor of the different species. These preferences could be impacting hybridization. Their outcomes have been published in an article entitled: “Conspecific olfactory preferences and interspecific divergence in odor cues in a chickadee hybrid zone” in Ecology and Evolution.
Huynh and Rice caught wild birds from hybrid zone populations in Pennsylvania. They used gas-chromatography mass-spectrometry to research differences between the species within the natural oils the birds produce from their uropygial glands (also called the preen glands). They examined the species’ odor preference using a Y-maze, measuring the amount of time a bird spends with a particular smell.
The experiments indicated a clear choice for same-species whole-body odors in each species of chickadees. These preferences were present in each male and female birds. The results, the team says, are consistent with a possible role for olfactory signaling in premating reproductive isolation in chickadees.