Adam K. Janke Michael J. Anteau Aaron T. Pearse Anthony D. Fox Johan Elmberg Jacob N. Straub Michael W. Eichholz Celine Arzel Joshua D. Stafford 2014 <p><span>Spring migration is a key part of the annual cycle for waterfowl populations in the&nbsp;northern hemisphere, due to its temporal proximity to the breeding season and&nbsp;because resources may be limited at one or more staging sites. Research based on field&nbsp;observations during spring lags behind other periods of the year, despite the potential&nbsp;for fitness consequences through diminished survival or cross-seasonal effects of&nbsp;conditions experienced during migration. Consequently, conservation strategies for&nbsp;waterfowl on spring migration are often only refined versions of practices used&nbsp;during autumn and winter. Here we discuss the current state of knowledge of habitat&nbsp;requirements for waterfowl at their spring migratory sites and the intrinsic and&nbsp;extrinsic factors that lead to variability in those requirements. The provision of plant&nbsp;foods has become the main conservation strategy during spring because of the birds&rsquo;&nbsp;energy requirements at this time, not only to fuel migration but to facilitate early&nbsp;clutch formation on arrival at the breeding grounds. Although energy sources are&nbsp;important to migrants, there is little evidence on the extent to which the availability&nbsp;of carbohydrate-based food is limiting for many migratory waterfowl populations. &nbsp;Such limitation is relatively unlikely among populations that exploit agricultural grain&nbsp;during migration (e.g. arctic-nesting geese), suggesting that conservation strategies for&nbsp;these populations may be misplaced. In general, however, we found few cases in&nbsp;which an ecological understanding of spring-migrating waterfowl was sufficient to&nbsp;indicate true resource limitation during migration, and still fewer cases where&nbsp;conservation efforts ameliorated these limitations. We propose a framework that aims&nbsp;to address knowledge gaps and apply empirical research results to conservation&nbsp;strategies based on documented limitations and associated fitness impacts on&nbsp;migrating waterfowl. Such a strategy would improve allocation of scarce&nbsp;conservation resources during spring migration and greatly improve ecological&nbsp;understanding of migratory waterfowl and their habitats in the northern hemisphere.</span></p> application/pdf en Wildfowl Trust Spring migration of waterfowl in the Northern Hemisphere: a management and conservation perspective article