Microbes Left Behind by Hyenas Offer 'Bulletin Board' of Information for Others

When wild hyenas mark a spot with a scent post, the bacteria left behind contain a wealth of information about the animals that left them, according to a new research paper in the journal Proceedings of the National Academy of Sciences.

Kevin Theis, the paper's lead author and a postdoctoral researcher Michigan State University, equated the scent posts to 140-character Twitter messages of the animal world.

"When hyenas leave paste deposits on grass, the sour-smelling signals relay reams of information for other animals to read," Theis said. "Hyenas can leave a quick, detailed message and go. It's like a bulletin board of who's around and how they're doing."

Bacteria in the scent pastes, much more than the researchers anticipated, is delivering much of the information contained in the scent post.

"Scent posts are bulletin boards, pastes are business cards, and bacteria are the ink, shaped into letters and words that provide information about the paster to the boards' visitors," Theis said. "Without the ink, there is potentially just a board of blank uninformative cards.

The bacterial communities within the hyena's scent glands showed a strong correlation with the gland's odor profiles, which the researchers say is indicative that bactria were responsible for variations in scent.

Theis and his colleagues, including MSU zoologist Kay Holekamp, studied both striped hyena and spotted hyena in Kenya, learning that the diversity of odor-producing bacteria in the spotted hyena's scent glands is much greater than previous studies have suggested. The bacterial diversity, however, consistently varied between hyena species and even among species depending on their gender and reproductive state.

"There have been around 15 prior studies pursuing this line of research," Theis said. "But they typically relied on culture-based methods, an approach in which many of the similarities and differences in bacterial communities can be lost. If we used those traditional methods, many of the key findings that are driving our research wouldn't be detected at all."

Theis said his study was the first to combine microbial surveys and complementary odor data from wild hyenas. The results of the research leave him eager to return to the field, Theis said.

"Now I just need to get back into the field to test new predictions generated by this study," he said. "The next phase of this research will be to manipulate the bacterial communities in hyenas' scent glands to test if their odors change in predictable ways."