Risk perception by endangered European bison Bison bonasus is context (condition) dependent

Abstract

Context: Patch use can illustrate the contributions that forage quality and foraging risk make in shaping foraging decisions made under the risk of being killed. Objectives: We aimed to determine whether forage selection by European bison Bison bonasus was state-dependent in being shaped by risk (wolf predation or human poaching/culling avoidance) or nutrient quality at two time periods—early winter (when resources are abundant) and at the end of winter (when resources are scarce)—in Białowieża Primeval Forest (Poland). Methods: We used a giving-up density framework using the proportional consumption of hay provided by humans to measure the perceptions of risk in European bison. Results: European bison resource selection was primarily driven by minimising the distance they travel over open ground in early winter (i.e. avoiding humans), however by the end of winter, when resources are scarce, bison selected haystacks for their nutrient quality (low fibre, high Mg and energy). Conclusions: This study illustrates how resource selection varies according to the condition of animals (i.e. state-dependency affects the marginal value theorem). It also indicates conservation managers using hay quality may actively manage human–bison conflicts in trouble spots and that bison are currently free from top-down limitation in Białowieża as they do not perceive wolves as threatening enough to alter their foraging behaviour.