Laserfiche WebLink
River from Lexington downstream to Grand Island was monitored from 1985 through <br />1990 (Lingle 1993b). <br />Riverine <br />From 1985 through 1990 failures in 37% of the unsuccessful tern nests were due to <br />flooding, and 37% due to predation (Lingle 1993a, 1993b). <br />Sandpits <br />Sandpits account for the majority of the tern and plover nesting in the Central Platte <br />River but have low reproductive success due to predation, human disturbance, and <br />weather (Lingle 1993a). Predation (37 %) was the greatest cause of nest failure on <br />sandpits, followed by human disturbance and weather. Only 3% of the sandpit nests were <br />lost to flooding, compared to 37% of the river nests. Human disturbance and <br />abandonment accounted for 27% of sandpit nests that failed and only 17% of the failed <br />river nests. Dogs /coyotes (canis latrans) were suspected in 38 (78 %) cases; skunks <br />(Mephitis mephitis) in 3 (6 %), raccoon (Procyon lotor), great horned owl (Bubo <br />virginianus) and American crow (Corvus brachyrhynchos) in two (4 %) each; and great <br />blue heron (Ardea hereodias) and snake in one (2 %) each. Other potential predators <br />included mink (Mustela vison), American kestrel (Falco sparverius), black - billed magpie <br />(Pica pica), bullsnake (Pituophis melanoleucus sayi), and garter snake (Thamnophis spp.) <br />(Lingle 1993a). <br />Three factors influenced nesting success at sandpits during a study conducted in 1989 and <br />1990: l') flooding, 2) predation and 3) failure of the eggs to hatch (Wilson et al. 1993). <br />Predation was observed in 1990 and several eggs failed to hatch for unknown reasons in <br />both years (Wilson et al. 1993). <br />Predation accounted for 35% of nest losses from 1985 through 1990. Suspected <br />predators were dog/coyote in eight (73 %) cases and skunk, American crow and snake in <br />one case each (9% each) (Lingle 1993a). <br />Artificial islands: From 1991 to 1997 three island sites constructed by NPPD were <br />monitored. A total of 42 least tern nests were found at two of the island sites (Elm Creek, <br />and Overton — no least tern nests were found at Lexington Island). Of these, 32 nests <br />hatched at least one chick for a nest success of 76 %. A total of 69 chicks hatched, of <br />which 50 chicks fledged, for a fledge ratio of 1.19 chicks fledged per nest. Fifteen <br />percent of nest loss for least terns was due to predation, 5% to unknown causes and 2% to <br />weather (Plettner and Jenniges 1999). <br />Managed sandpits: From 1994 to 1997 a total of 134 least tern nests were monitored on <br />managed pits. Nest success was 70 %. Seventy -three percent of all hatched chicks <br />survived to fledging (Jenniges and Plettner 1999). <br />Draft Baseline Report, July 2002 <br />4 -11 <br />