Patterns & processes in a multi-predator community

Understanding the multiple factors that structure predator populations is necessary for making informed wildlife management decisions, including knowledge of how one predator species affects another predator species. However, functional (i.e., behavioral) and numerical (i.e., abundance) relationships between predators can vary across spatial and temporal scales and are often mediated by prey dynamics, environmental factors, and human activities. Thus, characterizing patterns of predator occurrence and density, as well as identifying the relative importance of competition, prey, habitat, and anthropogenic pressures in shaping those patterns, can provide valuable information for managing predator populations. As a research scientist with the University of Idaho studying predator populations, my research objectives are to 1) identify patterns of co-occurrence and relative abundance among a community of predators in northern Idaho, and 2) describe processes (e.g., habitat, anthropogenic, or prey-availability correlates) that influence the strength of predator interactions and observed patterns. In collaboration with the Idaho Department of Fish and Game (IDFG), I am using camera trap data collected from 750 camera traps deployed across three game management units (GMU) from 2020 to 2022 to study demographic and spatiotemporal patterns associated with predator interactions. I am using a number of quantitative tools, including multi-species occupancy models and structural equation models, to test hypotheses about how competition and predator-prey relationships influence predator habitat use and the population sizes of interacting species. More details to come!

Spatiotemporal patterns of predator-prey interactions

The non-consumptive effects of predator-prey interactions take numerous forms and occur over a broad range of spatial and temporal scales. These interactions can shape the space-use and activity patterns of species in a wildlife community and may ultimately dictate when and where consumptive interactions are likely to occur. My doctoral research was part of the larger Washington Predator-Prey Project, a collaborative study between the University of Washington and Washington Department of Fish and Wildlife, aimed at understanding the impacts of recolonizing wolves on deer, elk, and other species in Washington State. Under the umbrella of the WPPP, I used a combination of camera trap data, GPS collar data, and various hierarchical models to answer questions about occurrence, movement, and activity patterns among a community of ungulates, mesopredators, and apex predators in eastern Washington, with a particular emphasis on how predator-prey interactions and anthropogenic activities influence these patterns. I asked four broad research questions: 1) how does survey perspective (camera trap vs GPS collars) influence inferences gained about wildlife-habitat associations and space use, 2) how does predator hunting mode and habitats associated with predators and prey influence animal movement, 3) how do antipredator behaviors vary with predation risk at different temporal scales, and 4) how do anthropogenic activities (i.e., hunting and livestock grazing) influence spatial and temporal overlap of predators and prey? I found that 1) inferences about wildlife-habitat associations were similar across sampling perspectives at coarse levels of inferences but finer details were often vastly different, 2) both predators and prey adjusted their movements in response to one another but not based on predator hunting mode, 3) how ungulates shifted their temporal activity in response to predation risk varied by species and with season and likely reflected antipredator behaviors to juggle predation risk from multiple species simultaneously, and 4) animal space-use and activity changed in diverse and sometimes unexpected ways in response to cattle and hunter activity, with the potential to alter predator-prey interactions in some cases.

Thanks to a dedicated group of UW undergraduate students and Microsoft's AI for Earth MegaDetector, we processed over 4 million images collected over the course of the study. I defended my dissertation in early November 2022 and the first chapter of my dissertation was published in Ecological Applications. Stay tuned for more updates!

Related Publications

Bassing, S.B., L. Satterfield, T.R. Ganz, M. DeVivo, B.N. Kertson, L.R. Prugh, T. Roussin, A.J. Wirsing, and B. Gardner. Predator-prey interactions and landscape features influence movement behaviors in a large-mammal community. Ecology. In Press.

Bassing, S.B., C. Ho, and B. Gardner. 2024. Anthropogenic activities influence spatiotemporal patterns of predator-prey interactions. Global Ecology and Conservation. 53:e03017.

Bassing, S. B., M. DeVivo, T. R. Ganz, B. N. Kertson, L. R. Prugh, T. Roussin, L. Satterfield, R. M. Windell, A. J. Wirsing, and B. Gardner. 2023. Are we telling the same story? Comparing inferences made from camera trap and telemetry data for wildlife monitoring. Ecological Applications 33(1):e2745.

Effects of harvest on wolf populations in the Rocky Mountains

Public harvest is frequently used to manage wildlife populations and mitigate human-wildlife conflict. Because of their social structure, the response of wolf populations to harvest management can be complex and understanding that complexity can help wildlife managers evaluate the efficacy of management, meet management objectives, and inform future decisions. My thesis focused on understanding how pubic harvest affected the distribution of wolf packs in southwestern Alberta, where wolves were managed under a long-term harvest regime, and whether immigration into packs maintained population densities in southwestern Alberta and in central Idaho, where harvest management only recently began. Using hunter surveys, non-invasive genetic data collected from scat, and occupancy models, I found that the number and distribution of packs in southwestern Alberta were stable during my study period, but observed frequent turnover of individuals in the study packs, suggesting that harvest affected within-pack dynamics more so than between-pack dynamics. Using a variety of genetic analyses and generalized linear models I also found that harvest reduced the density of pack-dwelling wolves in central Idaho but immigration did not change in response to harvest. The density of wolves and proportion of immigrants detected in southwestern Alberta were similarly low, suggesting that immigration does not always compensate for harvest mortality, as is often assumed. Learn more about the ongoing research this study was a part of at https://www.graywolfresearch.org/.

Related publications

Bassing, S.B., D.E. Ausband, M.S. Mitchell, M.K. Schwartz, J.J. Nowak, G. Hale, L.P. Waits. 2020. Immigration does not offset harvest mortality in groups of a cooperatively breeding carnivore. Animal Conservation. 23(6):750-761.

Bassing, S.B., D.E. Ausband, M.S. Mitchell, P. Lukacs, A. Keever, G. Hale, L Waits. 2019. Stable pack abundance and distribution in a harvested wolf population. Journal of Wildlife Management 83(3):577-590.