Peter Thompson

Title: Quantifying human-wildlife interactions from camera trap data using Poisson process models

Date: Friday, March 1st, 2024
Time: 1:15PM (PDT)
Location: ASB 10900

Abstract:  Humans have altered nearly every corner of the Earth, particularly in terrestrial areas, and this has negatively affected a variety of living things. A common manifestation of this problem is that many terrestrial animals are wary of or displaced by humans, but are simultaneously forced to occupy the same parts of the landscape as them. When wildlife are displaced by humans, or are less likely to occur in areas where humans are present, anthropogenic development can drastically reduce landscape connectivity, and in turn, population health, for these wary species. Policymakers and land managers must incorporate these dynamics when regulating how humans use different parts of the landscape to ensure that connectivity, at some level, is maintained. Doing this effectively requires exact estimates of how human use affects wildlife use in areas where the two parties must coexist. We observed these relationships passively using camera traps, a powerful tool for collecting data on multiple species at once, including humans, over a wide temporal range. Camera traps produce a set of "detection events" for each species representing spatial locations (i.e., the camera's location) and times when the animal was detected. These detections could be thought of as having arisen from a non-homogeneous Poisson point process with an intensity rate that could vary spatially and/or temporally. We fit a suite of Poisson process models to the set of detections for grizzly bears and wolves, separately, to identify differences in interactions between each of these species and humans. Our models suggest that non-motorized human activities, such as hiking or biking on trails, can have dramatic effects on grizzly bear and wolf detection rates when these activities occur in high density. The spatial "zone of influence" of these effects was also found to reach for over 1 km, and was wider for wolves than for grizzly bears. These figures are greater than previous estimates in the literature which may be a consequence of our cumulative technique for quantifying human use across the study area. These results can be used to inform managers about the potential consequences (or benefits) of different land management and regulation strategies.