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<br />minimizing such impacts are essential to the interior least <br />tern's recovery. <br />3111. Evaluate Dredator imDacts on eEES and chicks and <br />identifv sDecies resDonsible for the Dredation. <br />Predation can be high in California and coastal <br />least tern colonies (Atwood et al. 1979, Burger <br />1984, Massey 1981). Surveys on the Lower <br />Mississippi River revealed that' nest predation, <br />especially by coyotes, has substantially reduced <br />reproductive success at certain colonies. The <br />vulnerability of terneries to such predation <br />increases when island habitat accretes to the <br />shoreline during periods of low water (Smith and <br />Renken 1990). Studies conducted in the Missouri <br />River system have documented a high percentage of <br />interior least tern egg and chick loss to predation <br />(Nebraska Game and Parks Commission, unpublished <br />data, Mayer and Dryer 1990). During 1987-1989, <br />predation accounted for most of the nest losses on <br />the Platte River except riverine 'nests on the <br />central Platte where flooding caused the mortality <br />(Kirsch 1990, Lingle 1989). Both avian and <br />mammalian species are among the suspected predators. <br />Further studies that document such losses should <br />continue. Investigations that focus specifically on <br />identifying predators, and the cues they use in <br />locating nests and/or chicks, determining the time <br />of predation, etc., are necessary if egg and chick <br />mortality are to be curtailed. <br />3112. Evaluate techniQues for Dredator manaEement and <br />imDlement where aDDrODriate. <br />Lethal and non-lethal methods for managing mammalian <br />predators have been extensively developed for other <br />wildlife management purposes. They include: <br />eliminating or relocating the animal, erecting <br />electric fences, and developing taste aversions. <br />Electric fences have been used to protect nesting <br />California and coastal least terns (Massey and <br />Atwood 1980, 1982; Minsky 1980). The applicability <br />of these and other techniques (e. g. predator <br />exclusion cages) to the interior least tern should <br />be investigated. Few management efforts have <br />focused on managing avian predators, such as common <br />ravens (Corvus ~), American crows, great horned <br />owls (Bubo virEinianus), great blue herons (Ardea <br />herodias), California gulls (Larus californicus), <br />and ring-billed gulls (1. delawarensis). <br />Appropriate management measures should be <br />implemented at interior least tern sites that are <br />now experiencing significant and repeated loss due <br />to predation. <br /> <br />39 <br />