Abstract
AbstractPassive acoustic monitoring is a promising method for surveying wildlife populations that are easier to detect acoustically than visually. When animal vocalisations can be uniquely identified on an array of sensors, the potential exists to estimate population density through acoustic spatial capture–recapture (ASCR). However, sound classification is imperfect, and in some situations, a high proportion of sounds detected on just a single sensor (‘singletons’) are not from the target species. We present a case study of bowhead whale calls (Baleana mysticetus) collected in the Beaufort Sea in 2010 containing such false positives. We propose a novel extension of ASCR that is robust to false positives by truncating singletons and conditioning on calls being detected by at least two sensors. We allow for individual-level detection heterogeneity through modelling a variable sound source level, model inhomogeneous call spatial density, and include bearings with varying measurement error. We show via simulation that the method produces near-unbiased estimates when correctly specified. Ignoring source-level variation resulted in a strong negative bias, while ignoring inhomogeneous density resulted in severe positive bias. The case study analysis indicated a band of higher call density approximately 30 km from shore; 59.8% of singletons were estimated to have been false positives.
Publisher
Springer Science and Business Media LLC
Subject
Applied Mathematics,Statistics, Probability and Uncertainty,General Agricultural and Biological Sciences,Agricultural and Biological Sciences (miscellaneous),General Environmental Science,Statistics and Probability
Reference36 articles.
1. Akaike H (1998) Information theory and an extension of the maximum likelihood principle. In: Selected papers of Hirotugu Akaike. pp 199–213. Springer
2. Blackwell SB, McDonald TL, Kim KH, Aerts LAM, Richardson WJ, Greene CR Jr, Streever B (2012) Directionality of bowhead whale calls measured with multiple sensors. Mar Mamm Sci 28(1):200–212
3. Blackwell SB, Richardson W, Greene C Jr, Streever B (2007) Bowhead whale (Balaena mysticetus) migration and calling behaviour in the Alaskan Beaufort Sea, autumn 2001–04: an acoustic localization study. Arctic 60(3):255–270
4. Blackwell SB, Thode AM, Conrad AS, Ferguson MC, Berchok CL, Stafford KM, Marques TA, Kim KH (2021) Estimating acoustic cue rates in bowhead whales, Balaena mysticetus, during their fall migration through the Alaskan Beaufort Sea. J Acoust Soc Am 149(5):3611–3625
5. Borchers DL, Buckland ST, Zucchini W (2002) Estimating animal abundance: closed populations. Springer, London