Wildlife behavior, relative encephalization and extinction [electronic resource]
Keywords: Biology.

Biological diversity is currently undergoing immense losses that only rival extinction events found in the geological record 1,2. Conservation biology is focused on providing principles and tools for preserving that biological diversity 3. However, in his seminal 1985 paper, Michael Soulé describes conservation biology as a "crisis discipline." It remains, to this day, a crisis-oriented science due largely to the extreme complexity of the environment, variety of environmental perturbations and the relative lack of robust predictive tools. My dissertation aims to partially fill the gap between proactive and responsive conservation biology by examining wildlife behavior, and a proxy for behavior, to better understand human wildlife interactions and a biologically relevant predictive tool for quantifying species' extinction risk respectively. I explore three main foci: 1) I examine visitation frequency changes of black-tail mule deer (Odocoileus hemionus) in the presence of human-generated stimuli and if responses to these stimuli bias the ability to monitor this species. I find that deer visit sites with TrailMaster camera traps, monitoring devices that make sounds and flashes of light, less frequently, and for a shortened duration, compared to sites where TrailMaster camera traps are not present. 2) I examine if relative encephalization, believed to be a proxy for behavioral flexibility 4, is positively correlated with Carnivoran species extinction resistance over geologic time frames. In this study I find three significant trends. First, species with increased relative encephalization are generally found to have decreased relative extinction risk. Second, species with larger body sizes are generally at increased relative extinction risk. Finally, there is an interaction effect between brain size and body size on relative risk of extinction such that the role that brain size plays on relative extinction risk is greatest at small body sizes. 3) I test the relationship between relative encephalization and endangerment status in modern mammalian species. Results from this study find that, in modern species, those with larger relative encephalization are generally more likely to be endangered. Additionally, there is an interaction between relative encephalization and body size such that changes in relative encephalization are predicted to be accompanied with the greatest change in probability of endangerment in relatively smaller bodied species. However, there are some important differences when comparing the results from modern mammals in terms of the role of body size. The degree to which body size alone is related to endangerment depends on the geographic range of species. If species are included from a global distribution, large body size is associated with an increased probability of endangerment. Conversely, at some smaller geographic scales, for example only including species from North America, provides a differing result such that large bodied species are less likely to endangered. This may be due to historical "extinction-filtering" events where past extinction pressures may have caused differential species survival.