|
<br />~: The interior least tern is piscivorous, feeding in shallow
<br />waters of rivers, streams and lakes. Other least terns also feed on
<br />crustaceans, insects, mollusks apd annelids (Whitman 1988). The terns
<br />usually feed close to their nest~ng sites. Fish prey is small sized and
<br />important genera include Fundu~us, Notroois, Camoostoma, Pimeohales,
<br />Gambusia, Blonesox, Morone, Dorosbma, Leoomis and Caroiodes (Grover 1979,
<br />Hardy 1957, Rumancik 1988,1989; Schulenberg et al. 1980, Smith and Renken
<br />1990, Wilson et a!. 1989). Moseley (1976) believed least terns to be
<br />opportunistic feeders, exploiting any fish within a certain size range.
<br />Fishing occurs close to the riverine colony. Terns nesting at sand and
<br />gravel pits and other artificial habitats may fly up to 3.2 km to fish.
<br />Radio-tagged terns at Salt Plains, National Wildlife Refuge often traveled
<br />3.2-6.4 km to fish (Talent and Hill 1985). Fishing behavior involves
<br />,
<br />hovering and diving over standin& or flowing water.
<br />
<br />Intersoecific Interactions: Interior least terns are breeding
<br />associates of the piping plover (Charadrius melodus) in the Missouri River
<br />system (Dryer and Dryer 1985, ,Faanes 1983, Nebraska Game and Parks
<br />Commission 1987, Schwalbach 1988) and the snowy plover (Charadrius
<br />alexandrius) and American avocet (Recurvirostra americana) in the Arkansas
<br />River system (Grover and Knopf 1982, Hill 1985). Nesting piping plovers
<br />usually can be found within or n~ar nesting interior least terns at sand
<br />and gravel pits and on riverine ~andbars.
<br />,
<br />
<br />Habitat Reauirements
<br />Least terns throughout North America nest in areas with similar habitat
<br />attributes.
<br />
<br />Coastal Areas: Coastal and California least terns usually nest on
<br />elevated portions of level, unvegetated substrates near foraging areas
<br />(Carreker 1985). Beaches, sand pits, sandbars, islands and peninsulas are
<br />,
<br />the principal breeding habitats (Moseley 1976). Nesting can be cloBe to
<br />water but is usually between thejdune environment and the high tide line
<br />(Akers 1975, Blodget 1978). Unconsolidated substrate such as small
<br />stones, gravel, sand, debris an~ shells comprise the nesting substrate.
<br />A mixture of coarse sand, shells and other fragments may be preferred over
<br />fine-grained substrates because of better cryptic qualities, stability in
<br />wind, and water permeability (Burroughs 1966, Craig 1971, Gochfeld 1983,
<br />Jernigan et al. 1978, Soots and ~arnell 1975, Swickard 1972, Thompson and
<br />Slack 1982).
<br />
<br />Vegetation at California an~ coastal least tern nesting sites is
<br />sparse, scattered and short. Veietation cover is usually less than 20% at
<br />the time of nesting (Craig 1971, lThompson and Slack 1982, Gochfeld 1983).
<br />Least tern colonies in denser vegetation may be a response to habitat loss
<br />or a function of strong site tenacity.
<br />
<br />Rivers: The riverine nesting areas of interior least terns are
<br />sparsely vegetated sand and gra~el bars within a wide unobstructed river
<br />channel, or salt flats along lake shorelines. Nesting locations usually
<br />are at the higher elevations 4nd away from the water's edge because
<br />
<br />20
<br />
|