AUTHORS: Abigail G Blake-Bradshaw, Forbes Biological Station; Therin M Bradshaw, Forbes Biological Station; Andrew D Gilbert, Forbes Biological Station; Joshua M Osborn, Forbes Biological Station; Elizabeth A Beilke, Forbes Biological Station; Chelsea S Kross, US Fish & Wildlife Service; Auriel MV Fournier, Forbes Biological Station
ABSTRACT: Hunting pressure and associated disturbance influences many aspects of wildlife behavior. Disturbance by hunters influences the timing of relocation movements of waterfowl and could drive departures from stopover locations during autumn. Additionally, environmental conditions, including short-term changes in weather or habitat availability, may necessitate shifts in activity patterns, alter departure decisions, or impact individual susceptibility to harvest. Thus, wildlife professionals are interested in understanding what drives autumn-winter movements and migration events of waterfowl; therefore, we evaluated the extent to which hunting pressure and environmental conditions influenced daily flights and departure from an autumn stopover location. Our study took place in of the La Grange Reach of the Illinois River Valley, IL, USA. To evaluate the influence of “hunting pressure” on waterfowl behavior and departure from a stopover location, we placed 20 Autonomous Recording Units (ARUs) across our study area to quantify daily shotgun volleys. We then captured 38 mallards (Anas platyrhynchos) and 26 green-winged teal (A. crecca; hereafter teal) at Chautauqua National Wildlife Refuge, IL, USA. We deployed GPS-GSM transmitters on both age (i.e., juveniles and adults) and sex classes (i.e., males and females) and tracked both species during autumn and winter 2022–2024. We quantified the number of daily local-scale flights and related it to local environmental conditions and hunting pressure as indexed by ARUs. The median number of local-scale flights was 3 (range: 0–18) and was similar between species. Additionally, we identified the day individuals departed the Illinois River Valley stopover area by quantifying when they passed 40°N southwards, which marked the southern extent of our study area. In total, 24 teal and 8 mallards departed the study area, and as hunting pressure increased, teal were more likely to depart southwards. Preliminary results indicate mallards and teal responded to environmental conditions and hunting pressure disparately.
