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Dryad

Human access constrains optimal foraging and habitat availability in an avian generalist

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Jan 05, 2024 version files 16.09 MB

Abstract

Animals balance costs of anti-predator behaviors with resource acquisition to minimize hunting and other mortality risks and maximize their physiological condition. This inherent trade-off between forage abundance and quality, and mortality risk is intensified in human-dominated landscapes because fragmentation, habitat loss, and degradation of natural vegetation communities is often coupled with artificially-enhanced vegetation (i.e., food plots) creating high-risk high-reward resource selection decisions. Our goal was to evaluate autumn–winter resource selection trade-offs for an intensively hunted avian generalist. We hypothesized human access was a reliable cue for hunting predation risk and thus predicted resource selection patterns would be spatiotemporally dependent upon levels of access and their perceived risk. Specifically, we evaluated resource selection of local-scale flights between diel periods of 426 mallards (Anas platyrhynchos) relative to wetland type, forage quality, and differing levels of human access across hunting and non-hunting seasons. Mallards selected areas that prohibited human access and generally avoided areas that allowed access diurnally, especially during hunting season. Mallards compensated by selecting for high-energy and greater quality foraging patches on allowable human access areas nocturnally when they were devoid of hunters. Post-season selection across human access gradients did not return to pre-hunting levels immediately, perhaps suggesting a delayed response to reacclimate to non-hunted activities and thus agreeing with the assessment mismatch hypothesis. Last, wetland availability and human access constrained selection for optimal natural forage quality (i.e., seed biomass and forage productivity) diurnally during pre-season and hunting season, respectively; however, mallards were freed from these constraints nocturnally during hunting season and during post-season. Our results suggest risk-avoidance of human accessible (i.e., hunted) areas is a primary driver of resource selection behaviors by mallards and could be a local to landscape-level process influencing distributions, instead of forage abundance and quality, which has long-been assumed by waterfowl conservation planners in North America. Broadly, even an avian generalist, well-adapted to anthropogenic landscapes, avoids areas where hunting and human access is allowed. Future conservation planning and implementation must consider management for recreational access (i.e., people) equally important as foraging habitat management for wintering waterfowl.