BioacousTalks: Animal Density from Passive Acoustic Recordings with Tiago Marques

This is a recording of the BioacousTalks session from November 28th, where we welcomed Dr. Tiago Marques to speak with us about estimating animal density from passive acoustic recordings.

Tiago is a Senior Research Fellow at the University of St. Andrews, where he leads the ACCURATE Project, and an invited professor at the Universidade de Lisboa in Portugal. He is a leading expert on the topic of density estimation using acoustics.

Title: Estimating animal abundance using passive acoustics with a focus on ACCURATE results

Abstract: Historically, obtaining reliable estimates of animal abundance has depended on visual based methods, where a sample of animals would be detected or captured, and estimates of abundance obtained by correcting animals detected for those missed due to detectability and survey design. Nonetheless, there are a number of technologies, like DNA, satellite imagery, drones, camera traps or passive acoustics that have in recent years revolutionized how we count animals. In this talk we focus on passive acoustic monitoring (PAM) density estimation (DE), exploring different ways in which this can be done and what are the main issues one needs to consider to do so. Besides focussing on the animals themselves or on groups of animals, a major approach is cue counting, where a sample of detected sounds produced by the animals are used to estimate their density. Under such a setting, as in most other, we must care about detector performance, namely false negatives via detectability, and false positives, induced by error in detection or classification of sounds. Above and beyond those multipliers, and specific to cue counting, a cue production rate – the number of sounds produced per animal per unit time, is required to convert the number of sounds detected into animal density. Cue counting PAM based reliable estimates of animal density therefore depend upon using accurate and unbiased estimates of the cue rate, i.e., cue rates that correspond to the time and place the survey took place. The ACCURATE project, funded by the US Navy Living Marine Resources program, is a St Andrews-led large project involving several partners, looking at everything related to cue production, with a focus on marine mammals, to inform PAM DE exercises. We will briefly go over ACCURATE’s objectives and describe some of the outputs to date. We conclude with some discussion thoughts about what might be the future of passive acoustic density estimation.

This research was conducted under the ACCURATE project, funded by the US Navy Living Marine Resources program (contract no. N3943019C2176). TAM thanks partial support by CEAUL (funded by FCT - Fundação para a Ciência e a Tecnologia, Portugal, through the project UIDB/00006/2020).