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Understanding Waterfowl: Tracking the Mallard Migration

Research has provided a wealth of new information about mallard movements and habitat preferences
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By Luke Naylor and Andrew Raedeke, Ph.D.

Where are the ducks? Sometimes we can find the answer simply by checking out another part of a marsh or expanding our scouting area. Other times, however, these searches are in vain, which might lead us to conclude that ducks are absent from our part of the world. Are they north? Are they south? Are they all on a sanctuary? Likewise, waterfowl managers wonder where to restore and manage waterfowl habitat, how much is needed, and what proportion of this habitat should be set aside as sanctuary. Answers to these questions, along with those of hunters, require a thorough understanding of duck movements and habitat use during the nonbreeding season. 

Biologists know that dabbling ducks seek out resources in various habitats during fall and winter to complete a series of life-cycle events, such as the molt, pair bonding, and fat and protein accumulation. Decades of banding research helped define the routes that waterfowl follow during migration and can identify major stopover and wintering locations, but migration and habitat use by individual birds is less understood. Fortunately, technology and public interest recently intersected, creating an opportunity to broaden our understanding of mallard migration and habitat use during the nonbreeding period. 

During the early 2000s, a combination of declining duck populations and mild winters had hunters and biologists wondering if migration patterns were changing. In 2004, the Arkansas Game and Fish Commission (AGFC) embarked on a project capitalizing on new technology to track the movements of individual mallards throughout their annual cycle. Unlike more traditional radio telemetry methods, new satellite transmitters provided researchers with the ability to follow individual mallards thousands of miles from their wintering grounds to their breeding grounds. During 2004−2007, AGFC biologists marked nearly 200 mallards with satellite transmitters, mostly prior to spring migration. Other partners soon joined this effort, including the Mississippi Department of Wildlife, Fisheries, and Parks; Ducks Unlimited; the Mississippi Flyway Council; the Central Flyway Council; the USDA Natural Resources Conservation Service (NRCS); and the Livingston Ripley Waterfowl Conservancy. In total, partners in this study marked nearly 300 mallards in Arkansas, Mississippi, and Saskatchewan. 

Dr. Susan Sheaffer of the Livingston Ripley Waterfowl Conservancy and Dr. Richard Malecki, a professor emeritus at the Cornell Lab of Ornithology, provided expertise on marking birds and evaluating the performance of transmitters. Dr. David Krementz, of the Arkansas Cooperative Fish and Wildlife Research Unit at the University of Arkansas, and his students analyzed thousands of readings obtained from the nearly 200 mallards marked in Arkansas. More recently, Dr. Bill Beatty and Dr. Dylan Kesler of the University of Missouri teamed with Dr. Lisa Webb of the Missouri Cooperative Fish and Wildlife Research Unit to use GPS satellite telemetry data to determine which habitats mallards frequented during migration and winter.

But back to our original question, "Where are the ducks?" Fall migration often is perceived by hunters to be a drawn out affair, with ducks trickling down the flyways from north to south in response to weather events and habitat conditions. It's easy to imagine a scenario in which the migration might last a few months, beginning in mid-October and ending in mid-January. Instead, satellite-marked mallards completed fall migration in less than a month on average, with the majority of the birds starting their southward journey almost a month before freeze-up. In fact, 20 percent of the ducks marked in Arkansas during the winters of 2004−2007 returned south the next fall in one nonstop flight.

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