Date of Award

Spring 2005

Document Type

Restricted Thesis

Terms of Use

© 2005 M. Jawaad Hussain. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts




Background: A new area of research focuses on chemical signaling in birds and identification of bacteria that may produce those social odors. The Crested Auklet (Aethia cristatella) emits a distinct tangerine-like scent associated with breeding. Primary components of the odor, cis-4-decenal and octanal, may be produced from bacteria that metabolize secretions from the auklet's preen gland. The Least Auklet (A. pusilla), an unscented congener, co-exists with the Crested Auklet in some breeding locations, making the Least Auklet an ideal comparison species. One hypothesis to explain differential odor production between these two bird species is that they host different surface microbiota. Ultimately, this study of avian social odors aims to discover the profile of bacterial commensals associated with each bird, to elucidate the biochemical pathways involved in odor production, and to identify plausible candidate species responsible for the tangerine-odor. Our initial step was to compare the bacterial profiles from both the scented and unscented auklets as well as that of the domestic chicken (Gallus gallus domesticus). Methods: Bacteria collected from the feathers and preen glands of the three birds species were identified by ribotyping. DNA was extracted from whole feather homogenates. Using universal bacterial 16S primers, PCR products were cloned and sequenced. Bacterial identities were elucidated using a BLAST search. Results: After optimizing the DNA isolation protocols from collected feather samples, at least nine genera of bacteria from the tangerine-scented Crested Auklet,eight genera of bacteria from the Least Auklet, and nine genera from young domestic chicks have been identified. Conclusions: Currently, members of four genera are likely candidates to contribute to the production of the tangerine-like odor, because they are unique to the Crested Auklet: Yersinia, Bacillus, Xanthomonas, and Aeromonas. Furthermore, Pseudomonas and Psychrobacter are common to both Auklets, and Janthobacterium, Acinetobacter, and Burkholderia, were found to exist both on all three studied bird species.