Functional response is the framework thorough which we can quantify how predator hunting behaviors such as rate of successful attack and time spent handling prey interact with prey density to determine the rate at which prey are killed. Cheetahs are mesopredators and their behavior can be shaped by the need to avoid larger predators while hunting relatively large bodied and mobile prey. I used data from 34 years of observed cheetah hunts in Serengeti National Park in Tanzania to investigate how reproductive condition, prey density, seasonality, and the proximity of larger predators affect cheetah kill rates, probability of successful attack, and time spent handling prey. Mothers with cubs had an asymptotic Type II functional response where kill rate increased but eventually leveled-off at high prey densities, while cheetahs without cubs had a dome shaped Type IV functional response where kill rates actually declined at high prey density. Probability of successful attack on prey was higher for mothers with cubs, and increased slightly with prey density. Mothers with cubs had different prey handling behavior than other cheetahs. Cheetah mothers spend longer at kills then other cheetahs despite the risk that the carcass can attract lions and hyenas that could steal the carcass and potentially kill her cubs. Mothers must make sure their cubs have sufficient time at the carcass to eat their fill, thus they minimize risk from larger predators by being vigilant. In contrast, cheetahs without cubs are unconcerned with cub predation and can eat quickly to minimize the risk of kleptoparasitism. My results show how the pressures of cub rearing and coexisting with larger carnivores differentially shape the hunting behavior of cheetahs, and suggest that intensity of mesopredator suppression may depend on individual variability. This is the first time the functional response for a large mesopredator, has been quantified and the first time a dome shaped response has been recorded in a mammal. My work shows the value in accounting for individual variability in functional response and how linking of carnivore hunting behavior to multiple species interactions advances our understanding of how classical ecological theory applies to wild ecosystems. / Ph. D. / One of the most basic interactions between species is when one kills and eats another. Determining how many prey a predator kills is challenging, especially because it is difficult to observe hunting behavior in nature. To assess killing rates, we need information on prey density, the rate predators attack prey, and how long they spent killing and eating it. In smaller bodied predators (a.k.a. mesopredators), those behaviors are often influenced by the presence of larger, dangerous predators. I used 34 years of data on wild cheetahs in Serengeti National Park in Tanzania to examine whether their hunting behavior was influenced by having cubs, the proximity of lions and hyenas, and the season. I assessed how these factors affect the relationships between cheetah kill rates and gazelle density, the probability of a successful attack, and the time cheetahs spend handling their prey. I found that cheetah hunting behavior is largely shaped by whether or not they have cubs. Mothers’ kill rates are higher than cheetahs without cubs and stay high as gazelle densities increase. In contrast, the rate cheetahs without cubs kill declines at high gazelle density, the first time this relationship has been recorded in a wild mammal. Once prey are dead, mothers spend more time at the kill in order to ensure their cubs get enough time to eat. However, being at the kill is risky because lions and hyenas can arrive and kill her cubs. To minimize risks to cubs at the kill, mothers are more vigilant for predators than other cheetahs. Cheetahs without cubs spend less time at the kill, eating quickly without being vigilant. My results show how living in a landscape with multiple larger predators and mobile prey shapes the hunting behavior of all cheetahs, while providing detail on how having cubs can drive differences in those behaviors among individuals. The patterns of behavior seen in cheetahs may be indicative of how mesopredators alter hunting behavior to cope with pressures from larger predators. This is relevant as we craft conservation and management policies that take into account relationships among multiple carnivore species and their prey.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/82040 |
| Date | 07 February 2018 |
| Creators | Hilborn, Anne Winona |
| Contributors | Fish and Wildlife Conservation, Kelly, Marcella J., Durant, Sarah M., Karpanty, Sarah M., Walters, Jeffrey R. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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