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Am. Midl. Nat. 144:2835 Detecting Area sensitivity: A Comment on Previous Studies DAVID JOSEPH HORN AND ROBERT J. FLETCHER, junior Department of Animal Ecology, light Hall II, Iowa State University, Ames 50011 AND ROLF R. KOFORD Iowa conjunct Fish and Wildlife Research Unit, USGS-BRD, knowledge Hall II, Iowa State University, Ames 50011 ABSTRACT.several(prenominal) studies fox reported that most grassland birds are subject field raw; they exhibit a purposive avoidance of small ?elds. The methods get along sessiond to test for celestial sphere sensitivity, however, differed among studies. many investigators sampled ?elds with sampling effort proportionate to ?eld size, whereas others affaird represent sampling effort in all ?elds. We created a computer simulation model with the said(prenominal) number of ?elds and ?eld sizes as those examined in earlier studies to cook if birds that select habitat randomly would give away area sensitivity if ?elds w ere sampled in proportion to their size.

The three species that we sculpturesque to solve randomly, upland sandpiper (Bartramia longicauda), Henslows sparrow (Ammodramus henslowii) and eastern pipit (Sturnella magna), had dogmatic relationships between concomitant and ?eld size when a exhaust census or proportional sampling was used, and therefore, would have been considered area sensitive by the methods used by just virtually previous authors. When equal-effort sampling was used, these species showed no relationship between position and ?eld size. Future studies on area sensitivity that use proportional samp ling should compare results to a null model.! Otherwise, conclusions get up about area sensitivity may be skew-whiff because the response is a sampling artifact. INTRODUCTION One proposed motor for the population declines of grassland birds is habitat loss and fragmentation of their breeding rise (Herkert, 1994; Vickery et al., 1994; Warner, 1994; Igl and Johnson, 1997). Habitat fragmentation may result in a landscape of small habitat patches within a ground substance of unusable...If you want to get a full essay, order it on our website: OrderCustomPaper.com

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