Modeling Large Carnivore and Ranch Attribute Effects on Livestock Predation and Nonlethal Losses

Abstract

Predator-livestock interactions are a major concern for both agriculture and conservation globally. Using retrospective survey data from 274 ranches in Wyoming, United States, we used information theory to model how ranch attributes and large carnivores influenced the timing, duration, and severity of livestock predation. We then used constrained ordination to understand how 1) landscape, weather, and animal features influence predation and 2) how livestock behavior and nonlethal loss relate to ranch attributes and large carnivores. Timing, duration, and severity of livestock predation were generally not explained by ranch size or number of counties but were explained by livestock type, livestock parturition (either timing or duration), and documented large carnivore loss. Addition of the large carnivore loss variable to global models always improved Akaike information criterion scores. Rangelands characterized as rough, forested, shrubby, or a public grazing allotment reportedly increased predation risk, in part, due to large carnivore exposure. Approximately two-thirds of participants noticed livestock nervousness if a predator was nearby, half of participants noted changes in livestock distribution patterns, and a quarter of participants noted a reduction in livestock grazing time. Nonlethal losses such as lower weight gains, lower conception rates, lower birth rates, and delayed birth season were reported by 27%, 19%, 12%, and 11% of participants, respectively. Ordination revealed separation between behavioral changes and nonlethal losses, attributed to large carnivore exposure. Parturition relative to livestock type was also strongly correlated to timing and duration of predation for cattle-only operations but not for operations with sheep. The predictive cattle predation-parturition model suggests that for each additional month of calving, producers should anticipate 21 additional d of predation. Understanding predator-livestock interactions relative to ranch and rangeland features, parturition, large carnivore exposure, and losses that extend beyond mortalities can assist in developing novel strategies to mitigate lethal and nonlethal losses.