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higher flows is to nest on higher exposed sandbars but today much of the main channel areas are <br />clogged with trees and shrubs and are thereby no longer available. They do retreat to gravel pits <br />but mortality of the young is high due to predators whose hunting challenge is much reduced in <br />such small places that provide much inferior food sources (Currier, Lingle, and Walker 1985, p. <br />38-9). <br />Piping Plovers (charadrius melodus) are similar to least terns in that they much the same <br />habitat and compete for the same nesting sites. They differ slightly from least terns in that they <br />are a bit more tolerant of woody vegetation encroachment. This species was listed under the <br />Endangered Species Act as threatened in 1985. A 1991 census estimated its population in both <br />Canada and the U.S. to be about 2440 breeding pairs. The population is distributed from <br />southeastern Alberta to northwestern Minnesota and along prairie rivers and reservoirs to <br />southeastern Colorado. About 10% were estimated to breed primarily along rivers and 90% <br />nested around lakes and ponds (U.S. Fish & Wildlife Service 1997a). <br />Piping Plovers are a stocky robin-sized shorebird about 6-7 inches long with a wingspan of <br />about 14-15 inches (Forbush and May 1955). The head, back and wings are pale brown to gray <br />with black and white highlights. They are most easily identified by a black strip across the <br />forehead from eye to eye, a single black neck band, and white eye stripes. Like terns, plovers are <br />birds of the sandy shore where they are capable of racing at such speed that it is easy to confuse <br />their running with swift gliding. Beginning in May, females usually lay 4 eggs, one every other <br />day. Incubation lasts for something in the range of 25-31 days, after which well camouflaged <br />downy chicks survive by flattening themselves into the sand while parents feign crippling injury <br />to draw away predators-e.g., skunks, racoons, coyotes, bull snakes, owls and hawks. Young birds <br />can fly within about 21 days after hatching. Piping plovers walk or run from spot to spot seeking <br />to feed primarily on insects, larvae, and snails. <br />Much of their required habitat has gone the way of that also needed by least terns. Faster <br />fluctuating summer flows moving through incisecl channels laying between banks and islands <br />supporting dense woody vegetation has increasingly confined least terns and piping plovers to <br />ever more limited, fragmented, and scattered habitat. <br />14