By: Sara Knight
BU News Service

To mark the boundaries of our yards, most people plant hedges or construct fences. Hyenas, on the other hand, use paste – an oily, waxy, yellowish substance secreted from their anal glands.

Last fall I spoke with evolutionary ecologist Kevin Theis about his fascination with hyenas and his time spent tracking their various cliques as they roamed about the Kenyan Masai Mara National Reserve. During his time there, Theis became particularly interested in the hyenas’ scent-marking behavior.

Many mammalian species take advantage of their odiferous excretions – usually glandular goop, urine, or feces – to stake a claim to their territory. This behavior is known to biologists as “scent marking.” Hyenas mark their clans’ territory by extruding their anal pouch and dragging it along the ground, leaving a pungent paste trail behind them. Theis also suspects they use paste to communicate more nuanced information like fertility or advertising social status.

To determine the true nature of paste messaging, Theis first needed to identify what paste is exactly.Through a chemical analysis of the anal paste of hyenas from four different clans, Theis found that each group had a distinct “perfume” – allowing individuals to rapidly recognize if they were in a friendly or rival clan’s territory.

He also found that the waste products of microbial communities living within the hyenas’ anal pouches are responsible for paste’s distinctive odors. Each clan’s signature scent results from the unique composition of microbial species shared among that social group, meaning hyenas rely heavily on their resident cooperative microbe species for social communication.

Theis is continuing his work from the department of microbiology and molecular genetics at Michigan State University, where he aims to “elucidate the mechanistic roles bacteria play in the scent marking systems, and thus social lives, of solitary and social hyena species.” Read his blog here.