Factors Influencing a 24-Hour Time-Budget for Wintering Atlantic Brant
Date
2019-02-01
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Fish and Wildlife Management
Abstract
The wintering period is often a limiting time for waterfowl. To understand the behavioral dynamics of Atlantic brant Branta bernicla hrota wintering along coastal New Jersey, USA, we conducted observations across the full 24-h diel period in an effort to construct an accurate time-budget model for the wintering population. In most behavioral studies, it is only possible to collect diurnal and crepuscular behavior data, forcing the assumption that these data are representative of nocturnal behavior in order to model the full 24-h diel period. We collected behavior data in 5,902 instantaneous observational scans across 4 time periods (morning crepuscular, diurnal, evening crepuscular, and nocturnal) from the third week in October to the third week in February 2009–2010 and 2010–2011. Brant primarily allocated time toward swimming (43.5%), feeding (26.4%), resting (15.4%), and flying (7.7%); these proportions differed significantly across times of day. Brant exhibited decreased flight (4.8% vs. 9.3%) and feeding (22.3% vs. 29.6%) and increased resting behavior (24.4% vs. 10.5%) nocturnally compared with diurnal periods. We further modeled explanatory environmental variables, hunting effects (open vs. closed seasons, locations open vs. closed to hunting), and time of day (diurnal and nocturnal only) on wintering behaviors. Feeding, resting, and swimming behavior presence were most influenced by a predictive model of (Hunt Season × Hunt Location × Period) + (Tide × Period). Flight behavior presence were most influenced by a predictive model of (Hunt Season × Hunt Location × Period) + (Tide × Temperature). There is an interactive effect of hunting pressure and period of day on observed activity; therefore, our results demonstrate that not accounting for nocturnal variation in behavior can lead to biases when extrapolating to energy expenditure models. Additionally, hunting areas proved to be nocturnally valuable because these areas contain valuable energy resources that may be unavailable diurnally, and our observations show that brant will shift their activities around hunting pressures to make use of these areas.
Description
This article was originally published in Journal of Fish and Wildlife Management. The version of record is available at: https://doi.org/10.3996/032018-JFWM-023
Keywords
Atlantic brant, behavior, Branta bernicla hrota, New Jersey, nocturnal, time-energy budget, winter, life on land
Citation
Jeremiah R. Heise, Christopher K. Williams, Paul M. Castelli; Factors Influencing a 24-Hour Time-Budget for Wintering Atlantic Brant. Journal of Fish and Wildlife Management 1 June 2019; 10 (1): 79–90. doi: https://doi.org/10.3996/032018-JFWM-023