Designing occupancy studies: general advice and allocating survey effort
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This paper comments on a number of general issues related to designing occupancy studies, including the need for clear objectives that are explicitly linked to science or management, selection of sampling units, timing of repeat surveys and allocation of survey effort, and found that an optimal removal design will generally be the most efficient.Abstract:
Summary
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The fraction of sampling units in a landscape where a target species is present (occupancy) is an extensively used concept in ecology Yet in many applications the species will not always be detected in a sampling unit even when present, resulting in biased estimates of occupancy Given that sampling units are surveyed repeatedly within a relatively short timeframe, a number of similar methods have now been developed to provide unbiased occupancy estimates However, practical guidance on the efficient design of occupancy studies has been lacking
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In this paper we comment on a number of general issues related to designing occupancy studies, including the need for clear objectives that are explicitly linked to science or management, selection of sampling units, timing of repeat surveys and allocation of survey effort Advice on the number of repeat surveys per sampling unit is considered in terms of the variance of the occupancy estimator, for three possible study designs
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We recommend that sampling units should be surveyed a minimum of three times when detection probability is high (> 0·5 survey−1), unless a removal design is used
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We found that an optimal removal design will generally be the most efficient, but we suggest it may be less robust to assumption violations than a standard design
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Our results suggest that for a rare species it is more efficient to survey more sampling units less intensively, while for a common species fewer sampling units should be surveyed more intensively
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Synthesis and applications Reliable inferences can only result from quality data To make the best use of logistical resources, study objectives must be clearly defined; sampling units must be selected, and repeated surveys timed appropriately; and a sufficient number of repeated surveys must be conducted Failure to do so may compromise the integrity of the study The guidance given here on study design issues is particularly applicable to studies of species occurrence and distribution, habitat selection and modelling, metapopulation studies and monitoring programmesread more
Citations
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References
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Journal ArticleDOI
Estimating site occupancy rates when detection probabilities are less than one
Darryl I. MacKenzie,James D. Nichols,Gideon B. Lachman,Sam Droege,J. Andrew Royle,Catherine A. Langtimm +5 more
TL;DR: In this paper, a model and likelihood-based method for estimating site occupancy rates when detection probabilities are 0.3 was proposed for American toads (Bufo americanus) and spring peepers (Pseudacris crucifer).
Book
Occupancy Estimation and Modeling: Inferring Patterns and Dynamics of Species Occurrence
TL;DR: This chapter discusses single-species, Single-season Occupancy Models with Heterogeneous Detection Probabilities, and interspecific Relationships Between Species.
Journal Article
Statistical inference from capture data on closed animal populations
Journal ArticleDOI
A Practical Model of Metapopulation Dynamics
TL;DR: A novel approach to modelling of metapopulation dynamics is described, constructed as a generalized incidence function, which describes how the fraction of occupied habitat patches depends on patch areas and isolations.