Cost-benefit analysis of acoustic recorders as a solution to sampling challenges experienced monitoring cryptic species.

Emma M Williams,Doug P Armstrong,Colin F J O'Donnell

doi:10.1002/ece3.4199

Emma M Williams, Doug P Armstrong + Show 1 more

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https://doi.org/10.1002/ece3.4199

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Abstract

The inferences that can be made from any study are limited by the quality of the sampling design. By bad luck, when monitoring species that are difficult to detect (cryptic), sampling designs become dictated by what is feasible rather than what is desired. We calibrated and conducted a cost‐benefit analysis of four acoustic recorder options that were being considered as potential solutions to several sampling restrictions experienced while monitoring the Australasian bittern, a cryptic wetland bird. Such sampling restrictions are commonly experienced while monitoring many different endangered species, particularly those that are cryptic. The recorder options included mono and stereo devices, with two sound file processing options (visual and audible analysis). Recording devices provided call‐count data similar to those collected by field observers but at a fraction of the cost, which meant that “idealistic” sampling regimes, previously thought to be too expensive, became feasible for bitterns. Our study is one of the few to assess the monetary value of recording devices in the context of data quality, allowing trade‐offs (and potential solutions) commonly experienced while monitoring cryptic endangered species to be shown and compared more clearly. The ability to overcome challenges of monitoring cryptic species in this way increases research possibilities for data deficient species and is applicable to any species with similar monitoring challenges.

Highlights

Sampling designs dictate the strength of the inferences that can be made about a population of interest (Lambert et al, 2009; Thompson, White, & Gowan, 1998; Williams, Nichols, & Conroy, 2002)
This study aims to answer three questions: (a) How well do a number of calls detected with each recording option correlate with the number of calls detected by observers? (b) Is there a predictable relationship between the number of individuals detected listening to stereo recordings compared with the number detected by field observers? and (c) Are recording devices more cost-effective in terms of money and effort for monitoring?
In the case presented here, Australasian bitterns were a challenge to monitor due to several cryptic-species-specific characteristics and a few site-specific logistic constraints

Summary

Introduction

Sampling designs dictate the strength of the inferences that can be made about a population of interest (Lambert et al, 2009; Thompson, White, & Gowan, 1998; Williams, Nichols, & Conroy, 2002). When the cost of sampling an entire area of interest is too great, researchers subsample by defining sampling units considered representative of the area that has not been visited (Caughley, 1977; Thompson et al, 1998; Williams et al, 2002). In this way, biases caused by spatial variation can be limited using random-or stratified-sampling procedures. By bad luck, subsampling is problematic with cryptic species, as work on these species is logistically restricted. Such restrictions can prevent the application of many statistically valid

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