What Cues Do Ungulates Use to Assess Predation Risk in Dense Temperate Forests?

Abstract

Anti-predator responses by ungulates can be based on habitat features or on the near-imminent threat of predators. In dense forest, cues that ungulates use to assess predation risk likely differ from half-open landscapes, as scent relative to sight is predicted to be more important. We studied, in the Białowieża Primeval Forest (Poland), whether perceived predation risk in red deer (Cervus elaphus) and wild boar (Sus scrofa) is related to habitat visibility or olfactory cues of a predator. We used camera traps in two different set-ups to record undisturbed ungulate behavior and fresh wolf (Canis lupus) scats as olfactory cue. Habitat visibility at fixed locations in deciduous old growth forest affected neither vigilance levels nor visitation rate and cumulative visitation time of both ungulate species. However, red deer showed a more than two-fold increase of vigilance level from 22% of the time present on control plots to 46% on experimental plots containing one wolf scat. Higher vigilance came at the expense of time spent foraging, which decreased from 32% to 12% while exposed to the wolf scat. These behavioral changes were most pronounced during the first week of the experiment but continuous monitoring of the plots suggested that they might last for several weeks. Wild boar did not show behavioral responses indicating higher perceived predation risk. Visitation rate and cumulative visitation time were not affected by the presence of a wolf scat in both ungulate species. The current study showed that perceived predation risk in red deer and wild boar is not related to habitat visibility in a dense forest ecosystem. However, olfactory cues of wolves affected foraging behavior of their preferred prey species red deer. We showed that odor of wolves in an ecologically equivalent dose is sufficient to create fine-scale risk factors for red deer.

An adaptive behavioural response to hunting: surviving male red deer shift habitat at the onset of the hunting season

“…Deer probably assess predation risk using a variety of sensory cues, and presumably detect people and dogs using a combination of auditory, visual and olfactory inputs (Kluever, Howery, Breck, & Bergman, 2009;Kuijper et al, 2014;Lynch et al, 2014). Deer could be alerted by the heightened off-track human activity and the first gunshots.…”

A “death trap” in the landscape of fear

“…The prey may thus respond to predation risk at a fine scale within habitats and not between habitats, as shown by recent studies in BPF (Kuijper et al 2013). The predation risk perceived by ungulates may be yet more precisely fine-tuned based on olfactory cues as they showed unambiguous reaction to a single freshly deposited wolf scat (Kuijper et al 2014;Wikenros et al 2015). This ability may help them to perceive the actual vicinity or a recent visitation of a predator indicating near-imminent risk of death.…”

“…1). Moreover, the indirect cues of predation risk based on habitat features might primarily act at fine spatial scale (Kuijper et al 2013(Kuijper et al , 2014Wikenros et al 2015).…”

Challenges and science-based implications for modern management and conservation of European ungulate populations

“…The risks associated with predators' presence affect ecosystems through trophic, scale-dependent interactions (trophic cascades), emphasizing inseparable links between predators, herbivores and vegetation Ripple et al 2014Ripple et al , 2016. Prey species have evolved behavioural and physiological adaptations to the risks associated with predators (Creel et al 2007;Boonstra 2013;Kuijper et al 2014;Wikenros et al 2015). Herbivores may respond to predation risk by shifting foraging sites.…”