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ESTIMATING AMPHIBIAN OCCUPANCY RATES IN PONDS UNDER COMPLEX SURVEY DESIGNS
Citation:
Olsen, A R. ESTIMATING AMPHIBIAN OCCUPANCY RATES IN PONDS UNDER COMPLEX SURVEY DESIGNS. Presented at TIES 2004: The International Environmetrics Society and ACCURACY 2004: 6th International Symposium on Spatial Accuracy Assessment, Portland, ME, June 28-July 1, 2004.
Description:
Monitoring the occurrence of specific amphibian species in ponds is one component of the US Geological Survey's Amphibian Monitoring and Research Initiative. Two collaborative studies were conducted in Olympic National Park and southeastern region of Oregon. The number of ponds in each study region precludes visiting each one to determine the presence of particular amphibian species. A two-stage cluster probability survey design was implemented to select a subset of ponds for monitoring. The first stage primary sampling units are 5th field hydrologic units and the second stage are individual ponds located within each selected hydrologic unit. A common problem is that during a single visit to a pond, it is possible not to detect an amphibian species even when it is present, that is, the probability of detection is less than one. The objective of the survey is to estimate the proportion of ponds in each region that are occupied. Estimation of site occupancy rates when detection probabilities are less than one have been developed by MacKenzie et al. (2002) under the assumption of a simple random sample. Using the notion of generalized estimating functions, their procedures are generalized to cover not only two-stage cluster samples but more general complex survey designs.