Behavioral Responses Associated with a Human-Mediated Predator Shelter

Abstract

Human activities in protected areas can affect wildlife populations in a similar manner to predation risk, causing increases in movement and vigilance, shifts in habitat use and changes in group size. Nevertheless, recent evidence indicates that in certain situations ungulate species may actually utilize areas associated with higher levels of human presence as a potential refuge from disturbance-sensitive predators. We now use four-years of behavioral activity budget data collected from pronghorn (Antilocapra americana) and elk (Cervus elephus) in Grand Teton National Park, USA to test whether predictable patterns of human presence can provide a shelter from predatory risk. Daily behavioral scans were conducted along two parallel sections of road that differed in traffic volume - with the main Teton Park Road experiencing vehicle use that was approximately thirty-fold greater than the River Road. At the busier Teton Park Road, both species of ungulate engaged in higher levels of feeding (27% increase in the proportion of pronghorn feeding and 21% increase for elk), lower levels of alert behavior (18% decrease for pronghorn and 9% decrease for elk) and formed smaller groups. These responses are commonly associated with reduced predatory threat. Pronghorn also exhibited a 30% increase in the proportion of individuals moving at the River Road as would be expected under greater exposure to predation risk. Our findings concur with the ‘predator shelter hypothesis’, suggesting that ungulates in GTNP use human presence as a potential refuge from predation risk, adjusting their behavior accordingly. Human activity has the potential to alter predator-prey interactions and drive trophic-mediated effects that could ultimately impact ecosystem function and biodiversity.

Refuge or predation risk? Alternate ways to perceive hiker disturbance based on maternal state of female caribou

“…Our results showed that some lactating females left areas near a trail when hikers were frequent, but those that stayed were less vigilant within the 500‐m threshold distance from trails. This 500‐m threshold is relatively consistent with other studies of ungulates that have reported a human‐induced refuge from predators (Berger, ; Shannon et al., ). Although coyotes and black bears were found to use trails and gravel roads more often than expected based on random locations in our study area (see Gaudry, ; a companion study conducted in the Gaspésie National Park), the automated camera traps distributed along the hiking trails showed that no coyote and only a few black bears used trails in the hour following the passage of a hiker (F. Lesmerises & M.‐H.…”

“…This may occur even in parks where human activities are highly regulated (Whittington, St. Clair, & Mercer, ). In such cases, prey can modulate predation risk by exploiting the enemy‐free spaces created when the presence of humans and associated infrastructure displaces predators (i.e., the refuge hypothesis ) (Berger, ; Shannon, Cordes, Hardy, Angeloni, & Crooks, ; Steyaert et al., ). Predation risk varies in space and time, and thus, antipredator strategies should be adaptable to variation in risk.…”

The ecological effects of providing resource subsidies to predators

“…Such a possibility has been raised under circumstances where human harvesting of top predators hinders predators' ability to perform functional ecological roles (Ordiz et al, 2013). Human activity can also alter trophic cascades when prey use human presence as a refuge from predation (Shannon et al, 2014). Here we propose that this possibility be extended to circumstances where top predators focus on humanprovided foods, rather than on co-occurring predators and prey, and even more so where human-wildlife conflict leads to high rates of mortality of top predators.…”

Urbanization alters predator‐avoidance behaviours

“…Urban predators may also supplement their diet through anthropogenic resources which would reduce their need to hunt risky prey and further reduce their impact on prey populations (Morey, Gese, & Gehrt, ; Murray & St. Clair, ). In many cases, larger‐bodied predators avoid areas of high human activity (e.g., Shannon, Cordes, Hardy, Angeloni, & Crooks, ; Waser et al., ). However, some predators have adapted behaviours that allow them to persist in human‐dominated ecosystems—for example, increased nocturnality (Gaynor, Hojnowski, Carter, & Brashares, ).…”