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.
WHY USE CHEETAHS?
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 gazelles. We use these data to quantify the relationships between cheetahs, their predators, and their prey.
Conserving multiple carnivore species in protected areas
Carnivores are declining all over the world, and face a variety of threats including habitat loss, direct conflict with humans, and loss of prey species. Large protected areas such as national parks are seen as a way to shelter species from these threats, yet conservation issues still abound within them. The issues of how to conserve populations within protected areas will become more acute as habitat and species numbers decline outside of those areas. Carnivores present a particular challenge as they tend to be wide ranging and prone to a variety of conflicts with humans. Conserving multiple species of carnivores presents added difficulty as they have complex and sometimes negative relationships with each other. The ability for a species to coexist with predators and competitors is key for their survival, and becomes particularly pertinent inside of protected areas.
In Tanzania vast protected areas like Serengeti National Park contain sizable populations of lions, cheetahs, leopards, and spotted hyenas. These carnivore species interact in complicated ways and a species can negatively affect another. Lions and spotted hyenas are relatively numerous and are the dominant carnivores, not only because they hunt the largest herbivores like wildebeest and buffalo, but also because they harass and occasionally kill smaller carnivores.
As cheetahs and other carnivores come into more and more conflict with humans outside of protected areas, we need to find a way to conserve them inside of those areas. Despite the protection carnivores have in the Serengeti, cheetahs are slowly declining inside the park. If we are to have healthy populations of cheetahs as well as lions and other carnivores species, we must have management policies that take into consideration how species impact each other. Such policies need to be grounded in solid science, and my research works to provide that scientific basis.