Body mass in overwintering waterfowl is an important fitness attribute as it affects winter survival, timing of spring migration, and subsequent reproductive success. Recent research in Europe and the western United States indicates body mass of mallards (Anas platyrhynchos) has increased from the late 1960s to early 2000s. The underlying mechanism is currently unknown; however, researchers hypothesize that increases are due to a more benign winter climate, increased food availability through natural and artificial flooding, introgression of wild mallard populations by game-farm mallards, or shifting of wintering distributions northward. Further investigation of factors related to winter mallard body mass increases and whether this phenomenon is occurring in other major flyways could increase understanding of intrinsic and extrinsic variables influencing waterfowl fitness. We collected and analyzed mallard body mass data in the Lower Mississippi Alluvial Valley from 1979 to 2021 to determine sources of temporal variation. We measured hunter-harvested mallards from private hunting clubs, public hunting areas, and duck-plucking businesses. Mallard body mass increased by approximately 6% among all age-sex classes from 1979 to 2021. We also compiled weather data (rainfall [cm], weather severity index information [WSI], river gage discharge [cfs] and height [m]) to relate to mallard body mass measurements.

These data are outputs from a mallard (Anas platyrhynchos) reproduction model that accounts for breeding ground arrival time and the body mass of individuals. Specifically, adult female mallards that arrive late or with lower body mass have the potential for lower clutch sizes and are less likely to renest if a nest fails. The model is based on an existing mallard reproduction model that simulates mallards breeding in the Prairie Pothole Region of North America. We augmented the model using additional sources that provide alternative calculation of adult survival, first nest initiation probability, nest initiation date, renesting probability, renesting interval, brood loss date, and brood-rearing period. We also added components to the model that allow survival of adults, nests, and broods to increase. Changes to body mass and migration timing are both potential impacts of oil spills, so we executed the model with populations of 1000 female mallards that had different mean arrival dates and mean body masses. Model results are presented at the level of population and contain information such as survival rates for adults, nests, and broods; number of nests created by the population of adults, and the production of ducklings per adult female. In addition to model outputs, this release contains a pair of scripts that run the model.

Data and R Code for manuscript titled "Population Dynamics and Harvest Management of Eastern Mallards"

Data and R Code for manuscript titled "Population Dynamics and Harvest Management of Eastern Mallards"

This dataset describes responses to flushes by surveyors and predators for mallard and gadwall hens nesting on the Grizzly Island Wildlife Area, Suisun Marsh, California in 2015 through 2018. It includes the start time and duration of recesses, as well as the cause of recess initiation and responses of hens to various trapping activities at the nest site.

This dataset describes responses to flushes by surveyors and predators for mallard and gadwall hens nesting on the Grizzly Island Wildlife Area, Suisun Marsh, California in 2015 through 2018. It includes the start time and duration of recesses, as well as the cause of recess initiation and responses of hens to various trapping activities at the nest site.

The mallard (Anas platyrhynchos) is an abundant and wide-spread duck species that exhibits considerable variation in migratory behavior due to a relatively large body size and behavioral plasticity in habitat use. Understanding migration and other movements of mallards has societal interest in a wildlife management context because mallards are a preferred species of waterfowl by hunters and have the largest annual harvest of all duck species in the United States. We monitored juvenile mallards during autumn-winters 2018-2019 and 2019-2020 to determine factors associated with timing, distance, and direction of regional and migration movements during autumn-winter across the midcontinent of North America.

This dataset consists of three tables relating to (1) detections of adult McKay's Buntings from line transect with distance estimation surveys on St. Matthew and Hall islands in Alaska between May 30 and June 29, 2003 and June 6 and 11, 2018, (2) environmental covariates associated with detections of adult McKay's Buntings in less than or equal to 250-m long contiguous transect segments, and (3) environmental covariates used to predict McKay's Bunting population size in less than or equal to 300 x 300-m pixels across the study area in each year, and to estimate population change between years.

This dataset consists of three tables relating to (1) detections of adult McKay's Buntings from line transect with distance estimation surveys on St. Matthew and Hall islands in Alaska between May 30 and June 29, 2003 and June 6 and 11, 2018, (2) environmental covariates associated with detections of adult McKay's Buntings in less than or equal to 250-m long contiguous transect segments, and (3) environmental covariates used to predict McKay's Bunting population size in less than or equal to 300 x 300-m pixels across the study area in each year, and to estimate population change between years.

This data release contains three tables of information from the Colville River Delta, Alaska (CDR): offtake of Carex subspathacea (2012-2014), standing crop of C. subspathacea (2012-2014), and snow goose and black brant gosling mass data (2012-2017). Data were collected as part of the USGS Changing Arctic Ecosystems Initiative to understand the response of wildlife to rapid physical changes taking place in the Arctic.