Land Cover Switching in Autumn by Female Mallards in Ohio

Abstract

Autumn waterfowl habitat management often focuses on providing high energy food resources to attract and concentrate waterfowl for harvest. Similarly, many waterfowl conservation plans assume food resources are the primary, controllable limiting factor influencing waterfowl distribution during migration; however, hunting‐related disturbance also influences waterfowl distribution in autumn. We investigated factors influencing mallard (Anas platyrhynchos) movements in an intensively hunted and food‐rich landscape in Ohio, USA, during autumn of 2015 and 2016. We used locations from female mallards equipped with global positioning system (GPS) back‐pack‐transmitters to determine the probability of mallards switching land cover types based on seasonal and daily patterns of hunting disturbance and to determine the distances mallards moved between cover types that offer refuge and those that offer food resources as evidence for or against food resource depletion during the hunting season. Mallards switched cover types to exploit food‐rich but intensively hunted locations nocturnally and cover type switching during times subject to disturbance increased significantly from the early segment to the late segment of hunting season. Distances mallards moved between refuge cover types and food‐rich cover types did not change over the duration of the study. Hunting disturbance is a key variable influencing autumn movements and distribution of mallards, and mallards in a food‐rich and intensively hunted landscape likely employ nocturnal foraging as a strategy to survive autumn migration. Nocturnal foraging behavior has consequences for waterfowl managers tasked with providing quality waterfowl hunting opportunities because ducks that forage only at night are largely unavailable to hunters. © 2020 The Wildlife Society.

Influences of landscape composition on hunter‐harvested mallard body mass and condition in eastern Arkansas

“…First, forested systems offer more cover, thus making it easier for ducks to avoid predators (including human predators) and lowering energetically costly vigilant behaviors (e.g., flying, swimming; Reinecke et al 1989, Fredrickson and Batema 1992, Knapton et al 2000, Taylor 2010). Second, ducks could be maintaining energy levels by day roosting away from these compounds when hunting pressure is high (typically in the morning) and returning to use wooded wetlands in the afternoon, evening, or nighttime (Lancaster et al 2015, Shirkey et al 2020). Better understanding how woody wetlands may mitigate disturbances that would otherwise reduce mallard body mass and condition warrants future research.…”

Influence of sanctuary disturbance, weather, and landscape characteristics on waterfowl harvest opportunity in western Tennessee

“…McDuie et al (2021) demonstrated dabbling ducks (Anatini) doubled the time they spent flying during opening weekend in California, USA; presumably, increased movement between patches makes waterfowl more susceptible to hunters. Furthermore, waterfowl appear to adjust to hunting disturbance quickly, with many individuals using sanctuaries diurnally (Shirkey et al 2020, T A B L E 2 Model name, formula, number of parameters (K), Akaike's Information Criterion adjusted for small sample size (AIC c ), ΔAIC c , and negative log likelihoods (LL) for candidate generalized linear mixed models examining harvest opportunity, indexed by daily shotgun volleys per autonomous recording unit (ARU), in western, Tennessee, USA, during the November-January 2019-2022 general waterfowl hunting seasons. All continuous variables were standardized by subtracting the mean and dividing by one standard deviation.…”

“…While some stakeholders view sanctuaries as an important component of conservation planning that increases opportunities to see and harvest more waterfowl (Salyer 1945), others believe sanctuaries unnecessarily limit hunter access and attract waterfowl that might otherwise use areas accessible to hunters (Central Valley Habitat Joint Venture Technical Committee 1996). Waterfowl increase the use of sanctuaries diurnally, when they are largely inaccessible by hunters or viewers (Evans and Day 2002, Casazza et al 2012, Shirkey et al 2020, McDuie et al 2021). Consequently, there is intense sociopolitical pressure to alter sanctuary management and allow various activities and access (Devers et al 2017, Responsive Management and National Shooting Sports Foundation 2017, USDOI 2017).…”

Influence of resource selection on nonbreeding season mortality of mallards

“…Although there have been attempts to understand the influence of perceived mortality risk and physiological needs on resource selection of dabbling ducks ( Anas spp. ), the relationships remain tacit (Davis and Afton 2010, Palumbo et al 2019, Shirkey et al 2020).…”

“…Hunter harvest can be a major source of mortality for mallards (Fleskes et al 2007). Anthropogenic disturbance and mortality risk from hunting can influence local mallard distribution and movement, which results in individuals selecting inviolate refuges (i.e., sanctuaries) during the hunting periods (Madsen 1998, Brochet et al 2009, Dooley et al 2010 a , Shirkey et al 2020). In the Lake St. Clair region, mallards are abundant resource generalists and the most harvested waterfowl species.…”