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Estimating site occupancy rates when detection probabilities are less than one

Ecology

5924_MacKenzie.pdf
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Abstract

Nondetection of a species at a site does not imply that the species is absent unless the probability of detection is 1. We propose a model and likelihood-based method for estimating site occupancy rates when detection probabilities are < 1. The model provides a flexible framework enabling covariate information to be included and allowing for missing observations. Via computer simulation, we found that the model provides good estimates of the occupancy rates, generally unbiased for moderate detection probabilities (>0.3). We estimated site occupancy rates for two anuran species at 32 wetland sites in Maryland, USA, from data collected during 2000 as part of an amphibian monitoring program, Frogwatch USA. Site occupancy rates were estimated as 0.49 for American toads (Bufo americanus), a 44% increase over the proportion of sites at which they were actually observed, and as 0.85 for spring peepers (Pseudacris crucifer), slightly above the observed proportion of 0.83.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Estimating site occupancy rates when detection probabilities are less than one
Series title:
Ecology
Volume
83
Issue:
8
Year Published:
2002
Language:
English
Contributing office(s):
Patuxent Wildlife Research Center
Description:
2248-2255
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
2248
Last page:
2255
Number of Pages:
8