Examining inter-regional and intra-seasonal Differences in Wintering
Waterfowl Habitat Use Among Pacific and Atlantic Flyways and its
Application for Food Security in the U.S.
Abstract
The Central Valley of California (CVC) and Mid-Atlantic (MA) in the U.S.
are critical sites for wintering waterfowl. Mapping waterfowl
distributions using weather radar aids in the targeted adaptive
management by highlighting important waterfowl habitats. Additionally,
mapping broadscale waterfowl distributions improves food security by
allowing government agencies and commercial poultry operations to better
understand the interface between wild and domestic birds that is related
to risk of highly pathogenic avian influenza outbreaks. Improving
understanding of predictors of wintering waterfowl distributions at both
local and landscape scales will allow facility managers and regulatory
agencies to make more informed risk management decisions. We used 9
years (2014–2023) of data from the US NEXRAD network to model winter
waterfowl distributions in the CVC and MA as a function of weather,
temporal, and environmental characteristics using boosted regression
tree modelling. We captured the spatial-temporal variability in effect
size of 28 different covariates within two geographic regions which are
critical to nationwide waterfowl management and have a high density of
commercial poultry. In general, environmental, and geographic predictors
had the strongest relative effect on predicting wintering waterfowl
distributions in both regions, while effects of land cover composition
were more regionally and temporally specific. Increased daily mean
temperature was a major predictor of increasing waterfowl distributions
in both regions throughout the winter. Increasing waterfowl densities in
the CVC are strongly tied to the flooding of the landscape and rice
availability, whereas waterfowl in the MA, where water is less limiting,
are generally governed by waste grain availability and emergent wetland
on the landscape. Waterfowl distributions in the MA increased closer to
the Atlantic coast and lakes, while in the CVC they were higher nearer
to lakes. Our findings promote understanding of the predictors of winter
waterfowl densities in relationship with biosecurity of commercial
poultry nationally.