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SECTIONFIVE Piping Plover I I I I t I I , , I 1 ~ wide. horizontal visibility; protection from terrestrial predators; isolation from human disturbance; and sufficient protection from rises in river levels. Piping plovers are considered monogamous (having one mate) but will readily change mates and territories following nest failure and between years. After arriving at the breeding grounds, the male scapes several shallow, bowl-shaped depressions in the sand while vigorously calling to the female. The female then inspects each scape and selects one in which to lay her eggs. Nests are located on elevated areas with unvegetated sand, gravel, and cobble substrate, and they are sometimes placed near objects such as small pieces of drifrwood, stones, or bones which may make the nest less noticeable to predators. As stated previously, unobsoucted views are essential so adults can detect potential threats. Piping plovers usually lay four eggs which are olive to dull colored and are evenly marked with fine splotches of black. Both sexes share incubation duties which last an average of26 to 28 days (NGPC 1995). Female piping plovers have been known to renest up to five times in one season if their nests are destroyed. The average life span of a piping plover is thought to be about 3.5 years, but some individuals have lived up to 14 years (NGPC 1995). If a predator approaches a nest or chick, the adult piping plovers will frequently try to lead the predator away by performing the "broken wing" act. Most piping plovers in Nebraska nest in or near least tern nesting colonies and average nesting colonies in the state have 5 to 10 pairs of least terns and I to 3 pairs of piping plovers (NGPC 1995). This association is thought to be beneficial to piping plovers because the terns aggressively defend the colony area by mobbing the inOUder until it is chased away. Newly hatched chicks are precocial and within a few hours after hatching, the chicks leave the nest and are capable of running, feeding, and even swimming if necessary. Young plover chicks require a great deal of energy to grow and will forage almost constantly unless weather, fatigue, or the presence of a predator prohibits this activity. The chicks are capable of making short flights at about 20 to 25 days of age and are normally totally fledged by 28 days of age. Piping plovers forage for invertebrates at the substrate surface in open, wet, sandy areas along river systems and alkali v..ctlw.~d shorelines. In riverine locatio:!ls, foraging areas include the nesting area itself as well as adjacent sandbar flats. Com and Armbruster (1993) identified several patterns of invertebrate distribution and abundance of significance to piping plover foraging and breeding success. Their research emphasizes the importance of river charmel habitat for foraging. Although the food base is similar taxonomically between sandbars and spoil piles, invertebrate catch rates and densities are higher on river charmel sites. Invertebrates are distributed more or less uniformly across riverine foraging habitat but decline with increasing distance from water's edge at sand pit locations. Invertebrate catch rates increased more dramatically over the course of the summer on river channel sites than on aggregate mining sites. These patterns of invertebrate occurrence translated into greater foraging activity on river charmel sites even though only a small fraction of piping plovers nest on the river due to a lack of suitable nesting sites. The abiotic characteristic that most likely explains the differences in invertebrate catch rates between the river charmel and spoil pile sites is substrate moisture. The dominant invertebrate taxa collected from both sites were shore-inhabiting and semi-aquatic species associated with I/IIS tlnIilIer ~ CIJde 5-4 68F0D972!l6OO1<1.doc 6J2J'999(9,S2AM)/URSGWCFS12 FedenIIItInIt:a