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

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, ..., We captured male and female mallards in Tennessee from October–February 2019 through 2022. We banded ducks with U.S. Geological Survey aluminum tarsal bands and determined sex and age based on cloacal inversion, wing plumage and bill color (Carney 1992). We attached 20 g solar rechargeable and remotely programmable, OrniTrack Global Positioning System-Global System for Mobile transmitters (GPS-GSM; Ornitela, UAB Švitrigailos, Vilnius, Lithuania) to birds weighing ≥1,000 g to ensure deployment packages remained below 3 of an individuals’ body weight (Frair et al. 2010). We programmed GPS-GSM transmitters to record hourly locations throughout the duration of the study.
We filtered “used” locations to only those that were recorded within our spatial wetland extent data layer. Next, we generated 20-km circular buffers around used locations which corresponded to the maximum distance associated with local-scale flights (Appendix S1:Figure A1). We intersected 20-km buffers by our wetland data ..., , # Human access constrains optimal foraging and habitat availability in an avian generalist

The dataset was collected in western Tennessee where GPS-marked mallards were monitored across three winters (November through March 2019-2022). We used conditional logistic regression to fit step selection functions to model resource selection by male and female mallards during winter across three periods (pre-season, hunting season, and post-hunting season) and night vs. day.

We found that mallards selected areas free of human hunting and other disturbance (i.e., waterfowl sanctuary), which limited available habitat diurnally. However, mallards were freed from this constraint and selected \"riskier\" areas that were associated with hunting and other human disturbance nocturnally. Mallards selected sanctuary during pre-season, suggesting limited water availability and mallards did not immediately perceive human-accessible areas as safe during post-season, suggesting a lag-effect to reacclimate ...