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The Foraging Ecology of Royal and Sandwich Terns in North Carolina, USA

January 1, 2001

Population sizes of territorial male red-winged blackbirds (Agelaius phoeniceus) were determined with counts of territorial males (area count) and a Petersen-Lincoln Index method for roadsides (roadside estimate). Weather conditions and time of day did not influence either method. Combined roadside estimates had smaller error bounds than the individual transect estimates and were not hindered by the problem of zero recaptures. Roadside estimates were usually one-half as large as the area counts, presumably due to an observer bias for marked birds. The roadside estimate provides only an index of major changes in populations of territorial male redwings. When the roadside estimate is employed, the area count should be used to determine the amount and nature of observer bias. For small population surveys, the area count is probably more reliable and accurate than the roadside estimate.

Citation Information

Publication Year 2001
Title The Foraging Ecology of Royal and Sandwich Terns in North Carolina, USA
Authors T.W. McGinnis, S.D. Emslie
Publication Type Article
Publication Subtype Journal Article
Series Title Waterbirds
Index ID 1008234
Record Source USGS Publications Warehouse
USGS Organization Western Ecological Research Center