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Sampling large landscapes with small‐scale stratification
Author(s) -
Bart Jonathan,
Dunn Leah,
Leist Amy,
Sabin Laura
Publication year - 2012
Publication title -
the journal of wildlife management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.94
H-Index - 111
eISSN - 1937-2817
pISSN - 0022-541X
DOI - 10.1002/jwmg.384
Subject(s) - habitat , stratification (seeds) , sampling (signal processing) , wildlife , geography , physical geography , sampling design , scale (ratio) , stratified sampling , ecology , environmental science , cartography , statistics , biology , mathematics , population , botany , germination , demography , filter (signal processing) , dormancy , sociology , computer science , computer vision , seed dormancy
This study, carried out for the United States Bureau of Reclamation (BOR), demonstrated methods for surveying large landscapes using small‐scale, habitat‐based stratification, a common problem that has heretofore received little attention. The goal was to design a sampling plan for detecting change in the density of breeding birds of 6 species occurring along the Colorado River around and south of Lake Mead in the southwestern United States. The main problem in designing the study was that the focal species were concentrated in small, irregularly shaped patches of habitat. We partitioned the study area into >15,000 plots configured to enclose the high‐quality habitat in the fewest possible plots with the constraint that plots could be surveyed in 1 morning by 1 person. Because of the irregular plot shapes and extremely dense vegetation, we used area searches to carry out the surveys. We used double‐sampling, including a large sample of plots surveyed with a rapid method and a subsample of plots surveyed intensively, to estimate detection ratios. A simulation study helped allocate effort between rapid and intensive surveys and indicated that conducting 80 surveys per year would achieve high power to detect a 50% decline occurring during 20 years. This is one of the first studies to show how large landscapes can be sampled using small‐scale stratification so that effort can be concentrated in the habitats of greatest interest. © 2012 The Wildlife Society.