Phantoms of the forest: legacy risk effects of a regionally extinct large carnivore

Abstract

The increased abundance of large carnivores in Europe is a conservation success, but the impact on the behavior and population dynamics of prey species is generally unknown. In Europe, the recolonization of large carnivores often occurs in areas where humans have greatly modified the landscape through forestry or agriculture. Currently, we poorly understand the effects of recolonizing large carnivores on extant prey species in anthropogenic landscapes. Here, we investigated if ungulate prey species showed innate responses to the scent of a regionally exterminated but native large carnivore, and whether the responses were affected by human‐induced habitat openness. We experimentally introduced brown bear Ursus arctos scent to artificial feeding sites and used camera traps to document the responses of three sympatric ungulate species. In addition to controls without scent, reindeer scent Rangifer tarandus was used as a noncarnivore, novel control scent. Fallow deer Dama dama strongly avoided areas with bear scent. In the presence of bear scent, all ungulate species generally used open sites more than closed sites, whereas the opposite was observed at sites with reindeer scent or without scent. The opening of forest habitat by human practices, such as forestry and agriculture, creates a larger gradient in habitat openness than available in relatively unaffected closed forest systems, which may create opportunities for prey to alter their habitat selection and reduce predation risk in human‐modified systems that do not exist in more natural forest systems. Increased knowledge about antipredator responses in areas subjected to anthropogenic change is important because these responses may affect prey population dynamics, lower trophic levels, and attitudes toward large carnivores. These aspects may be of particular relevance in the light of the increasing wildlife populations across much of Europe.

Does wolf presence reduce moose browsing intensity in young forest plantations?

“…Predation risk has so far hardly been considered as a driver of ungulate impact on forestry. Recent work, however, suggests that the openings in forest habitat created by forestry may change the reaction of ungulates in response to predation risk (Sahlén et al 2015). In this study, ungulates reduced their use of forest habitat after the introduction of brown bear scent, but not if this habitat was relatively open due to human influence (e.g.…”

“…However, the impact of ungulates on these young forest plantations has resulted in strong conflicts with the forestry industry (Danell et al 2003, Ezebilo et al 2012. Recent work, however, suggests that the openings in forest habitat created by forestry may change the reaction of ungulates in response to predation risk (Sahlén et al 2015). Predation risk has so far hardly been considered as a driver of ungulate impact on forestry.…”

Landscapes of Fear: Spatial Patterns of Risk Perception and Response

“…Our framework highlights pathways through which disturbance alters and creates landscapes of fear. Changes in land use through agriculture [108] and deforestation [109], as well as pollution [110], shape habitat structure, quality, and heterogeneity. Human activity thus alters the playing field for predator-prey dynamics, changing the effectiveness of predator and prey strategies and prey trade-offs, constraining the spatial scale of prey responses, and sometimes even altering sensory cues [99].…”

Zooming in on mechanistic predator–prey ecology: Integrating camera traps with experimental methods to reveal the drivers of ecological interactions

“…age of scent cues, Bytheway, Carthey, & Banks, 2013; or predator identity, Carthey & Banks, 2018) affect prey behaviour. Olfactory predator cues are the most commonly utilized in camera trap studies (Smith et al, 2020), often by deploying predator scat or urine at camera traps to assess vigilance behaviour and space use (Andersen, Johnson, & Jones, 2016; Carthey & Banks, 2018; Kuijper et al., 2014; Sahlén et al., 2016). Olfactory cues may indicate to prey that a predator uses the area but is not necessarily present and, as such, have been associated with a range of prey responses, from attraction (i.e.…”

“…Predation risk can have important non‐consumptive effects on prey populations and lower trophic levels, as mediated by costly behavioural responses, but it is often difficult to isolate these effects from those of actual consumption by predators in free‐ranging populations. Camera trap experiments with simulated risk cues, which manipulate just the fear of predators and thus isolate these behavioural costs, have demonstrated that perceived risk from predators can cause prey to forego foraging (Clinchy et al., 2016; Smith et al., 2017) and avoid otherwise valuable habitat (Fležar et al., 2019; Sahlén et al, 2016). Beyond measuring immediate antipredator responses to risk, simulated risk cues can be used to quantify such costs of antipredator behaviour.…”