avian chemical communication

Photo of preen oil sample collection
                            from a grackle

I am intrigued by the unseen external forces that influence our behavior, mate choice, and, ultimately, evolutionary trajectories. My research is focused on the interaction between the microbiome and animal behavior, and the resulting impact on evolutionary dynamics. Specifically, I study chemical communication in a songbird, the dark-eyed junco (Junco hyemalis), the uropygial gland microbiome’s role in the production and evolution of chemical signals present in preen oil, and the effects of social behavior on these symbiotic microbes.

Summary of Recent Publications

Photo of two pink-sided juncos

For a complete list of publications, see the CV page.

Whittaker, D. J., N. M. Gerlach, S. P. Slowinski, K. P. Corcoran, A. D. Winters, H. A. Soini, M. V. Novotny, E. D. Ketterson, and K. R. Theis. 2016. Social environment has a primary influence on the microbial and odor profiles of a chemically signaling songbird. Frontiers in Ecology and Evolution 4:90.

We investigated the relative contributions of shared environments and genetic relatedness in shaping juncos’ symbiotic bacterial communities, and tested whether these communities underlie juncos’ chemical signaling behavior. To address these questions, we sampled parents and nestlings at 9 nests during one breeding season. Mated adult pairs showed high bacterial similarity, and offspring were more similar to their mothers than fathers. When comparing offspring to their social fathers, paternity did not influence bacterial profiles; full siblings were not more similar than half siblings. Our data suggest that social environment is a primary driver of individual microbiota and odor profile structure among juncos: birds who are in close proximity and in frequent contact develop similar profiles.

Whittaker, D. J. and K. R. Theis. 2016. Bacterial communities associated with junco preen glands: ramifications for chemical signaling. In Chemical Signals in Vertebrates 13, eds. Bruce A. Schulte, Thomas E. Goodwin, and Michael H. Ferkin. New York: Springer International Publishing, pp. 105-117. (peer-reviewed book chapter)

We conducted a preliminary bacterial survey of the preen gland microbiome in free-living juncos. We found that, much like mammalian scent glands, the preen gland harbors diverse communities of symbiotic odor-producing bacteria. Two of the most common genera in junco preen glands, Burkholderia and Pseudomonas, are capable of producing over half of the volatile compounds present in junco preen oil, making these bacteria a candidate mechanism for odor production in juncos.

Whittaker, D. J. and N. M. Gerlach. 2016. Mate choice in dark-eyed juncos using visual, acoustic, and chemical cues. In Snowbird: Integrative Biology and Evolutionary Diversity in the Junco, eds. E. D. Ketterson and J. W. Atwell. Chicago: University of Chicago Press, pp. 281-309. (peer-reviewed book chapter)

This book chapter appeared in a book that was one of the results of Ellen Ketterson’s NSF OPUS grant. We reviewed junco preferences for visual, acoustic, and chemical traits in the context of mate choice. A large section of the chapter is devoted to reviewing the relatively recent literature on avian chemical signaling, focusing especially on our work in juncos. We ended by discussing the limits of what we can learn from typical mate-choice studies.

Whittaker, D. J., D. G. Reichard, M. Drouilly, K. Battle, and C. Ziegenfus. 2015. Avian olfactory displays: A new hypothesis for the function of bill-wiping in a social context. Behavioral Ecology and Sociobiology 69: 159-167.

We suggest that bill-wiping in social contexts – previously dismissed as a “displacement activity” – may function as an olfactory display that releases odor from preen oil dried on the bill and increases attractiveness, similar to self-grooming in mammals. In a field study, we presented resident male juncos with either a male or female intruder paired with vocalization playbacks to simulate either a same-sex territorial intruder, or a potential mate. We found that bill-wiping appeared to be an integral part of courtship, especially in younger males, but not of aggressive behavior. We also tested whether friction increased the attractiveness of dried preen oil in a captive Y-maze study, but the results were inconclusive.

Whittaker, D. J., N. M. Gerlach, H. A. Soini, M. V. Novotny, and E. D. Ketterson. 2013. Bird odour predicts reproductive success. Animal Behaviour 86(4): 697-703.

We measured preen oil volatile compounds in free-living adult juncos at the beginning of the breeding season, and tested their relationship with individual genetic reproductive success in that season. We found strong sex-specific relationships between reproductive success and sexually dimorphic volatile compounds, such that females with a more “female-like” odor and males with a more “male-like” odor had more offspring. Male odor was also correlated with survival of offspring in their home nest, as well as the number of extra-pair offspring in their nest. We conclude that preen oil volatile compounds may serve as reliable mate assessment cues in songbirds.

Press Coverage

Male dark-eyed junco, thurberi
                              subspecies