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There are 17 bridge segments between Lexington and Columbus. Not all of <br />these bridge segments may be able to support a colony of least terns. In <br />addition, it may take many nesting sites to form a colony. According to <br />average colony sizes (6 tern pairs per colony)38, there would need to be 25 tern <br />colonies to meet the recommended objectives. To spread the birds out as <br />much as possible, a significant portion of nesting birds should occur both in <br />the upstream and downstream sections of the central Platte River. Kearney is <br />chosen as the splitting point. The rationale for choosing the splitting point at <br />Kearney and for a broad distribution of birds is the same as discussed for the <br />piping plover in section A.5. Lb. <br />A.5.2.c. Fledge Rates <br />The fledge rate objective for the central Platte River should be 0.70 fledglings <br />per pair for a 3 -year running average for least terns. This recommendation is <br />based on current recruitment rates on the Platte River for various habitats over <br />the last 10 years, literature referenced, and discussions at the September 2000 <br />workshop. The following fledge rates are summarized data only to compare <br />current productivity on the Platte River to recommendations in the literature. <br />Sand pits managed by power districts = 0.99 tern chicks fledged/nest39 <br />(0.90 tern chicks /pair)40 <br />Unmanaged sand pits = 0.43 tern chicks fledged/nest39 <br />River dredged islands = 1.04 tern chicks fledged/nest39 <br />Lower Platte managed sand pits = 0.88 tern chicks fledged/pair4l <br />Lower Platter River sandbars = 0.21 - 0.73 fledglings /pair (1987 -90)42 <br />Lower Platte River sand pits = 0.28 - 0.64 fledglings /pair (1987 -90)42 <br />Lower Platte River unmanaged sand pits= 0.50 tern chicks fledged/pai0 3 <br />Lower Platte River sandbars = 0.68 tern chicks fledged/pair44 <br />In addition, in 2000 and 2001, an index of lower Platte River productivity was <br />generated by using the number of pairs observed on the river during the <br />summer airboat census, and the number of fledglings observed on follow -up <br />airboat surveys. The estimated fledge rate for the river was 0.44 tern <br />38 Nebraska Game & Parks Commission survey data. <br />39 Nebraska Public Power District data. <br />40 Central Nebraska Public Power & Irrigation District data. <br />41 Nebraska Game & Parks Commission data. <br />42 Kirsch, E. M. Habitat Selection and Productivity ofLeast Terns on the Lower Platte <br />River, Nebraska. Wildlife Monographs, No. 132, January 1996 <br />43 Nebraska Game & Parks Commission data for years 1984, 1986, 1990, 1993, 1994, <br />1997, and 1998. <br />44 Nebraska Game & Parks Commission data for years 1986, 1987, 1988, 1989, 1990, <br />1991, 1994, and 2001. <br />14 <br />