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Understanding Waterfowl: Drought and Deluge

We can't control the weather, but conserving wetlands and grasslands on the prairies will help ensure the long-term health of duck populations
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  • Populations of mallards and many other ducks closely track the abundance of small wetlands (May ponds) on the prairies, which are counted each year during spring waterfowl surveys.
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In addition, it has been known for a long time, since Professor Paul Errington's work at Iowa State University in the 1940s and 1950s, that numbers of mink generally follow the abundance of muskrats. When it's really dry, these wetland-adapted animals suffer too (smaller litters, reduced survival). And when water returns to the prairies, the wetlands and the ducks can respond much more quickly than do the resident mammals.

Nearly 50 years ago, Johnny Lynch, a pioneer USFWS survey biologist, famously observed that wet and dry patterns on the prairies drove the boom and bust years for duck production, while the more stable water areas in the northern parklands and southern boreal forest provided more predictable, but on average less productive duck habitat. Many times the boreal forest has proved to be an important redoubt in dry years, but the likelihood of drought-displaced prairie ducks breeding there seems to be rather low.

In the late 1980s waterfowl biologists, thinking about all these factors, realized that the key to sustaining healthy duck populations was "keeping the table set" over large landscapes for those strong production years that come along now and then. If wetland basins are intact—and not ditched, tiled, or filled—they will return to their natural productivity whenever the snow and rain allow. Similarly, if native grasslands, forage crops, or Conservation Reserve Program cover are in place when the water returns—as illustrated graphically in the Dakotas in the mid-1990s—duck numbers can explode. The challenge is to affect the "table" on a scale big enough to matter. That means applying every tool we have to protect and restore pothole basins and doing everything we can to keep the grass right-side up across the prairie landscape. 

Ensuring sufficient habitat to sustain healthy waterfowl populations will require broad public support for wetlands conservation. Fortunately, there is growing appreciation for the many benefits wetlands provide for society, especially during times of exceptionally wet weather. Intact wetlands can slow the flow of water over the land, giving creeks and rivers time to flow moderately and lessen the chance of catastrophic floods. Wetlands also take up excess nutrients like phosphorus and nitrates common in runoff from agricultural watersheds, minimizing harm to rivers, lakes, and municipal water supplies downstream.

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