Kansas travelers

Natural History, May, 1998 by Helen Hands

Imagine you're a semipalmated sandpiper migrating north from your wintering grounds in South America. You're well on your way, headed up the middle of the North American continent. Reaching Kansas, you fly over miles and miles of green winter wheat, milo stubble, and pasture. Then, right in the center of the state, seven miles northeast of Great Bend, you see a large, elliptical wetland that makes your mouth water. You swoop down and join the many other shorebirds at Cheyenne Bottoms.

The Western Hemisphere Shorebird Reserve Network has designated this bottomland as a site of hemispheric importance, one helping to support more than 500,000 shorebirds migrating along the midcontinental mute. Thirty-nine shorebird species have been identified at the bottoms. Of these, thirty are regular visitors. Among the most numerous are long-billed dowitchers, Wilson's phalaropes, and white-rumped, Baird's, stilt, and semipalmated sandpipers. While some birds stop only long enough to replenish energy reserves needed to continue their journey to more northerly nesting grounds, others, such as killdeers, snowy plovers, American avocets, upland and spotted sandpipers, and Wilson's phalaropes, remain to nest.

A 41,000-acre natural land sink, Cheyenne Bottoms was formed by geological forces about 65 million years ago; some 100,000 years ago, after river-borne sediments filled in the basin, it became a freshwater marsh. Today, the bottoms reflect years of shaping by human activity. Nine man-made, interconnected pools each cover more than 700 acres. Roughly 50 percent of the bottoms is privately owned and consists of native-grass pasture and cropland planted with wheat, Milo, and alfalfa. Areas set aside for wildlife include the Cheyenne Bottoms Wildlife Area, where I work as a biologist and monitor migrant and nesting shorebirds. These 20,000 acres in the southeast corner of the bottoms are adjoined by 6,772 acres owned and managed by the Nature Conservancy since 1990.

Overall numbers of shorebirds and the time of peak migration vary from year to year, depending on the availability of vegetated mudflats with less than five inches of water--the ideal habitat for incoming shorebirds. Migrants such as the semipalmated sandpiper are not likely to set down in alfalfa fields or in ten inches of water or in areas invaded by cattails.

In a marsh, the water level naturally fluctuates. In the bottoms, it can go from bone dry to five feet deep, as happened in 1992. Annual precipitation averages twenty-four inches, but in a typical year, even more water is lost to evaporation. Yet after a heavy rain, the water level can rise by as much as ten inches overnight. Such fluctuations help check the growth of dense stands of cattails, trees, and herbaceous plants, such as millet and dock. They also promote the proliferation of insects, including tremendous numbers of bloodworms (named for their often bright red color) that attract hungry shorebirds to the marsh.

Bloodworms are really not worms at all but the larval and pupal stages of midges--small flying insects similar to mosquitoes but without the tendency to bite. A study in the mid-1980s estimated the dry weight of bloodworm larvae in the bottoms during the six months spanning the shorebird migration period to be commonly in the 100-ton range (the equivalent of about 1,000 tons of live bloodworms). While some bloodworms can survive in the mud beneath flooded vegetation, most live submerged in mud where few plants grow.

Cheyenne Bottoms' natural sources of water--runoff, precipitation, and two creeks that flow into the basin--have been supplemented since the 1950s by flows diverted from the Arkansas River and one of its tributaries, Walnut Creek. These sources proved unreliable, however; starting in about 1970, the once-healthy marsh began suffering from water shortages, which led to the spread of cattails and the subsequent loss of open mudflats. As a result, shorebird numbers in the bottoms began a long decline.

An important turnabout came in 1992 when, after a severe drought, a landmark court decision ordered cutbacks in irrigation near Great Bend to allow more water to reach Cheyenne Bottoms.

The fight to keep mudflats clear of invading cattails continues. With favorable weather, large tractors to mow these tenacious plants, and persistence, we hope to reclaim more of the mudflats for the benefit of shorebird travelers.

RELATED ARTICLE: Birding the Coast of Kansas

The best time to see shorebirds at Cheyenne Bottoms is during spring migration, which spans mid-March to late May but usually peaks in late April and the beginning of May, depending on habitat conditions. The smaller fall migration starts in July, generally peaks in August and September, and ends by late October.

At the Cheyenne Bottoms Wildlife Area, you can watch birds from your car, driving the gravel roads that originally divided the marsh into five separate pools. Depending on overall water levels, the pools can be vast, and the birds can be close to the road or a few hundred yards away. Plan to bring a spotting scope, preferably with a window mount. Observing shorebirds from the roads allows you to use the car as a blind and makes flushing any nearby birds less likely. Before your trip, you can get the latest information on shorebird numbers and road conditions by calling Cheyenne Bottoms' twenty-four-hour hotline at (316) 793-7730.