Cost-efficient effort allocation for camera-trap occupancy surveys of mammals

Gálvez, Nicolás and Guillera-Arroita, Gurutzeta and Morgan, Byron J. T. and Davies, Zoe G. (2016) Cost-efficient effort allocation for camera-trap occupancy surveys of mammals. Biological Conservation, 204 (Pt B). pp. 350-359. ISSN 0006-3207. (doi:https://doi.org/10.1016/j.biocon.2016.10.019) (Access to this publication is currently restricted. You may be able to access a copy if URLs are provided)

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Official URL
http://dx.doi.org/10.1016/j.biocon.2016.10.019

Abstract

Camera-traps are increasingly used to survey threatened mammal species and are an important tool for estimating habitat occupancy. To date, cost-efficient occupancy survey effort allocation studies have focused on trade-offs between number of sample units (SUs) and sampling occasions, with simplistic accounts of associated costs which do not reflect camera-trap survey realities. Here we examine camera-trap survey costs as a function of the number of SUs, survey duration and camera-traps per SU, linking costs to precision in occupancy estimation. We evaluate survey effort trade-offs for hypothetical species representing different levels of occupancy (ψ) and detection (p) probability to identify optimal design strategies. We apply our cost function to three threatened species as worked examples. Additionally, we use an extensive camera-trap data set to evaluate independence between multiple camera traps per SU. The optimal number of sampling occasions that result in minimum cost decrease as detection probability increases, irrespective of whether the species is rare (ψ <0.25) or common (ψ >0.5). The most expensive survey scenarios occur for elusive (p <0.25) species with a large home range (>10 km2), where the survey is conducted on foot. Minimum survey costs for elusive species can be achieved with fewer sampling occasions and multiple cameras per SU. Multiple camera-traps set within a single SU can yield independent species detections. We provide managers and researchers with guidance for conducting cost-efficient camera-trap occupancy surveys. Efficient use of survey budgets will ultimately contribute to the conservation of threatened and data deficient mammals.

Item Type: Article
Subjects: Q Science > QH Natural history > QH75 Conservation (Biology)
Divisions: Faculties > Social Sciences > School of Anthropology and Conservation > DICE (Durrell Institute of Conservation and Ecology)
Depositing User: Zoe Davies
Date Deposited: 24 Oct 2016 15:57 UTC
Last Modified: 18 Jan 2017 11:47 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/58077 (The current URI for this page, for reference purposes)
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