Negotiating multiple cues of predation risk in a landscape of fear: what scares free‐ranging brushtail possums?

Abstract

Herbivores live in a landscape of fear and must incorporate danger in their foraging decisions, balancing their need of food and safety using a variety of cues to assess the risk of predation. These cues can either be direct (i.e. signalling the possible presence of a predator) or indirect (i.e. linked to the likelihood of encountering a predator). How then do herbivores negotiate these multiple cues in the landscape? And which type of cues do foraging herbivores use to assess variation in predation risk? We examined these questions by investigating the foraging responses of a free-ranging marsupial herbivore, the common brushtail possum Trichosurus vulpecula to perceived predation risk. We found that indirect habitatrelated cues of predation (i.e. feeder location) consistently influenced foraging, while other more variable indirect (i.e. illumination) and direct cues (i.e. predator odour) did not. Giving-up-density at above-ground feeders was always lower than at on-ground feeders. Possums spent more time and foraged more at the aboveground feeders than at the on-ground feeders. Our results demonstrate that when multiple cues are present, varying in the accuracy of the information they provide about predation risk, possums respond to habitat-related cues. Possums manage risk by modifying behaviours, reducing time spent foraging in areas where potential risk is perceived as high. Thus, when the location of a predator at a certain point in time and space is unknown, and food demands are high, habitat-related cues are a safe choice to assess predation risk, with reliable returns for free-ranging herbivores.

The dilemma of foraging herbivores: dealing with food and fear

“…These sub-lethal costs of predation can have as much influence on overall prey dynamics as mortality (Preisser et al 2005;Creel and Christianson 2008). Predation risk is often associated with indirect cues from the environment, including open habitat (Powell and Banks 2004) or moonlight , or for arboreal animals, being on the ground (Mella et al 2014); and with direct cues such as the scats and urine of predators (Apfelbach et al 2005). As these cues vary spatially and temporally (Carthey et al 2011;Hughes et al 2012;Price and Banks 2012), so does the landscape of fear (Laundre et al 2001;van der Merwe and Brown 2008).…”

Odours of non‐predatory species help prey moderate their risk assessment

“…A common presumption in studies of predator–prey interactions is that prey rely on direct and indirect predator cues to estimate risk (Grostal & Dicke, ; Lima & Steury, ; McCormick & Manassa, ; Mella, Banks, & McArthur, ). Direct cues include visual, auditory, chemical or tactile stimuli produced by the predator (Thorson, Morgan, Brown, & Norman, ).…”

“…to estimate risk (Grostal & Dicke, 1999;Lima & Steury, 2005;McCormick & Manassa, 2008;Mella, Banks, & McArthur, 2014).…”

Visit, consume and quit: Patch quality affects the three stages of foraging

“…Foragers can shift their absolute and proportional time allocation to different behaviours depending on their needs (Kotler, Brown, Mukherjee, Berger-Tal, & Bouskila, 2010). Often foraging is offset by vigilance under predation risk (Brown, 1999;Kotler, Brown, & Bouskila, 2004) or patches are quit early (Mella, Banks, & McArthur, 2014), but whether differences in food quality yields similar shifts in behavioural allocation is relatively unknown (but see Foley, Iason, & McArthur, 1999;Wiggins, McArthur, McLean, & Boyle, 2003).…”