Where to forage when afraid: Does perceived risk impair use of the foodscape?

Abstract

The availability and quality of forage on the landscape constitute the foodscape within which animals make behavioral decisions to acquire food. Novel changes to the foodscape, such as human disturbance, can alter behavioral decisions that favor avoidance of perceived risk over food acquisition. Although behavioral changes and population declines often coincide with the introduction of human disturbance, the link(s) between behavior and population trajectory are difficult to elucidate. To identify a pathway by which human disturbance may affect ungulate populations, we tested the Behaviorally Mediated Forage‐Loss Hypothesis, wherein behavioral avoidance is predicted to reduce use of available forage adjacent to disturbance. We used GPS collar data collected from migratory mule deer (Odocoileus hemionus) to evaluate habitat selection, movement patterns, and time‐budgeting behavior in response to varying levels of forage availability and human disturbance in three different populations exposed to a gradient of energy development. Subsequently, we linked animal behavior with measured use of forage relative to human disturbance, forage availability, and quality. Mule deer avoided human disturbance at both home range and winter range scales, but showed negligible differences in vigilance rates at the site level. Use of the primary winter forage, sagebrush (Artemisia tridentata), increased as production of new annual growth increased but use decreased with proximity to disturbance. Consequently, avoidance of human disturbance prompted loss of otherwise available forage, resulting in indirect habitat loss that was 4.6‐times greater than direct habitat loss from roads, well pads, and other infrastructure. The multiplicative effects of indirect habitat loss, as mediated by behavior, impaired use of the foodscape by reducing the amount of available forage for mule deer, a consequence of which may be winter ranges that support fewer animals than they did before development.

Mismatch Between Risk and Response May Amplify Lethal and Non-lethal Effects of Humans on Wild Animal Populations

“…This functional habitat loss, in addition to physical habitat loss, is rarely quantified when identifying available habitat for populations (Northrup et al, 2015). Avoidance of anthropogenic structures dramatically reduces the habitat and resources available to animals through the act of over-response to human activity (Lesmerises et al, 2018;Dwinnell et al, 2019).…”

An applied ecology of fear framework: linking theory to conservation practice

“…Restricting visitor access has led to the restoration of breeding by snowy plovers (Charadrius alexandrines nivosus) in coastal California (Lafferty, Goodman, & Sandoval, 2006) and reduced stress responses of fur seals (Arctocephalus australis) in Uruguay (Cassini, Szteren, & Fern andez-Juricic, 2004), for example. Furthermore, given that animals often exhibit fearful responses to anthropogenic infrastructure that extend beyond its physical footprint (Sawyer et al, 2017;Dwinnell et al, 2019), spatial planning of development should consider potential animal behavioral response (Smith, Duane, & Wilmers, 2019).…”

“…Although it is not often possible or necessary to tease these effects apart, demographic models should consider effects of predators on prey beyond just per capita consumption. Similarly, when predicting the outcomes of anthropogenic development or activity for animals, the range of possible scenarios should include potential non-lethal demographic effects and reduced habitat as a result of prey avoidance of disturbed habitat perceived as risky (Dwinnell et al, 2019).…”

Spatiotemporal variation in disturbance impacts derived from simultaneous tracking of aircraft and shorebirds

“…Whether disturbance ultimately affects survival will also depend on the available food sources and weather conditions, since these determine the ability of animals to compensate for disturbance (Burton, 2007;Goss-Custard et al, 2006). Animals can also avoid disturbed areas which may limit available breeding or foraging areas (Dwinnell et al, 2019;Leblond et al, 2013;Mallord, Dolman, Brown, & Sutherland, 2007).…”