Sanctuary for migrating and wintering waterfowl: Synthesis and insights for waterfowl management and conservation planning

Abstract Waterfowl use a diversity of resources (e.g., food, structure, sanctuary) to meet energetic, social, and other life‐history demands during the non‐breeding period. Waterfowl often seek areas with limited human disturbance (i.e., sanctuary) during autumn and winter when hunting seasons are open perhaps to reduce exposure to mortality risks, minimize energy expenditure, and increase foraging efficiency, all of which should enhance survival and subsequent fitness. Prior studies of sanctuary use by waterfowl have mostly focused on patterns of abundance and behavior, with many documenting differential diel movements of marked birds in and around sanctuaries. Although reduced mortality risk is likely associated with sanctuary use, much less is known about the potential effects on energy expenditure, body condition, reproductive consequences at the individual level, and seasonal distribution with respect to viewing and harvest potential. We consider these aforementioned factors among the most significant gaps in our understanding of the function of sanctuary in waterfowl management. As waterfowl hunter recruitment, retention, and reactivation have become a major initiative of many natural resource agencies and a core principle of the North American Waterfowl Management Plan, we discuss the potential role of sanctuary relative to these efforts. Herein, we review historical aspects of waterfowl sanctuary, introduce hypotheses about its potential role in habitat resource management and conservation planning during autumn and winter, discuss our knowledge of the effects of sanctuary on waterfowl, and share insights to inform decisions about the role of sanctuary in waterfowl management given currently available evidence and remaining uncertainties. Our review describes the existing evidence for the biological and social outcomes of sanctuary, draws some conclusions about the role of sanctuary in natural resource management given the available evidence, and outlines potential research opportunities to help us make informed decisions regarding sanctuary implementation for waterfowl.