Kaia Tombak

Princeton University
Managing Protected Areas to support fitness-enhancing social behaviour in an endangered zebra

Kaia Tombak, Cecley Hilll, Eleanor Pressman, Daniel Rubenstein

Models of the demographic structure of animal populations are an important and widely-used tool to assess the current state and future prospects for their growth. However, whether a population fulfills its potential for growth depends on whether the animal’s environment allows it to group and range according to its needs. The endangered Grevy’s zebra, a bulk feeder with an inefficient digestive system, spends about 60% of its time grazing. In larger groups, food competition increases but per capita vigilance rates go down, allowing each zebra more time to feed. Group membership in this species is fluid to allow adjustments in response to the pushes and pulls of the dynamic predation risk and resource distribution in their habitat. This flexibility is important to consider when managing a Grevy’s population to maximize recruitment: young foals are the most vulnerable to predation and rely on their mothers’ vigilance to avoid lions precisely at the stage when their mothers need to graze the most to provide enough energy for themselves and their rapidly-growing, nursing foals. Accordingly, the only Grevy’s zebras that form stable groups are lactating females, which band together to share the benefits of each other’s vigilance at this vulnerable stage. I will discuss how this temporary shift in social behaviour and traditional local land use practices can be used to maximize recruitment in areas harbouring Grevy’s zebras.

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Tuesday, December 11