Anne Hilborn

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My PhD Research



                       How do multiple carnivore species coexist?












Especially how do smaller carnivores (mesopredators) coexist with lots of larger ones?  What behavioral strategies do smaller carnivores use to survive when there are lots of bigger carnivores around that would steal their kills and/or possibly kill them? Specifically how does having to navigate a landscape with lots of large carnivores affect the hunting behavior of smaller predators who are targeting mobile prey? How do the behavioral strategies mesopredators use to coexist with apex predators in turn affect their prey species?













To  get at these questions, I study cheetahs in Serengeti National Park in Tanzania.




Many of the current predator prey models consider the effect of one predator species on one prey species. However, most species live in diverse communities and predators often have predators of their own. Apex predators can impact mesopredators directly by killing them, competing with them for food, or driving them out of certain habitats, all of which could impact the mesopredator's functional response. Since a majority of predators are not apex predators, understanding how these behaviors affect functional response will allow us to make modeling more applicable for more species and make better predictions about how prey populations with multiple predators respond to population changes in apex or mesopredator predator species.


Serengeti cheetahs provide an incredible oppurtunity to do detailed studies of hunting behavior for a number of reasons.


1.       The open plains allow us to find cheetahs.




















2. Unlike many other carnivores, cheetah hunt during the day

















3. Lions and hyenas steal kills from cheetahs and pose a predation threat to their cubs.
















These combinations of traits allow us to obtain remarkably detailed observational records of cheetah hunting behavior that we can then link to the presence or absence of lions and hyenas as well as gazelle density. I use these data to quantify the relationships between cheetahs, their predators, and their prey.


My dissertation focused on functional response which a way of quantifying the way that the density of prey interacts with predator behaviors  to determine the rate at which predators kill their prey.  With the data  what densities of prey cheetahs spend time and hunt in as well as on the amount of time cheetahs spend handling their prey I could quantify cheetah kill rates depending on season, whether they had cubs or not, and whether lions were nearby.


I also investigated the behavioral strategies cheetahs use to minimize their risks from lions and hyenas.  Mothers with cubs modify their prey handling behavior differently from cheetahs without cubs as thier primary threat is other carnivores killing their cubs. Other cheetahs handle prey in ways that are consistant with trying to reduce the chance the kill will be stolen.


I am working to getting these results published, and then I can expand on the details.


















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