Hourly GPS location data from mallards (Anas platyrhynchos), green-winged teal (Anas crecca), and American wigeon (Mareca americana) transmittered in Arkansas

Movement of waterfowl during winter is central to resource acquisition and
mortality avoidance, despite the imminent risk to survival and overall
fitness induced by hunting disturbance and energy expenditure. Weather and
other environmental conditions may influence movement by altering resource
needs, in which ducks must balance the trade-offs of resource acquisition
and risk management. We compared how environmental factors influenced
total daily diurnal and nocturnal movement distances of three dabbling
duck species wintering in the Mississippi Alluvial Valley. We estimated
total daily diurnal and nocturnal movement distances of green-winged teal
(Anas crecca; n = 51), American wigeon (Mareca americana; n = 38), and
mallards (Anas platyrhynchos; n = 31) using backpack transmitters during
the winter period of February-November 2020-2021 and 2021-2022. We used
linear mixed effects models to model the influence of weather, hunt
season, day of season, and sex on total diurnal and nocturnal movement
distances by species. Green-winged teal moved 7.7% further during the
nocturnal period (x̄ = 3.38 km; SE = 0.32; p <0.001) than during
the diurnal period (x̄ = 3.13 km SE = 0.10), while American wigeon and
mallards moved 36.6% (x̄ = 4.95 km; SE = 0.20; p < 0.001) and 28.1%
(x̄ = 4.39 km; SE = 0.23; p < 0.001) further during the diurnal
period than the nocturnal period (x̄ = 3.42 km, SE = 0.28 and x̄ = 3.31
km, SE = 0.22), respectively. Fine-scale movement distances during the
diurnal period were weakly associated with environmental covariates for
all species. Conversely, moon illumination influenced nocturnal movement
distances for all species. Nightly movement distances of mallards
increased by 2.1 times from new to full moon during the hunting season.
Conversely, there were no changes in nocturnal movement distance during
pre-hunt and post-hunt periods when hunting disturbance was absent. In the
face of intensifying environmental pressures on movement patterns in
dabbling duck populations, this research demonstrates a behavioral
response to moon illumination as a mechanism for moving about the
landscape for resource acquisition in the presence of human disturbances
that induce risk, such as hunting.