The role of vocal individuality in conservation

Abstract

Identifying the individuals within a population can generate information on life history parameters, generate input data for conservation models, and highlight behavioural traits that may affect management decisions and error or bias within census methods. Individual animals can be discriminated by features of their vocalisations. This vocal individuality can be utilised as an alternative marking technique in situations where the marks are difficult to detect or animals are sensitive to disturbance. Vocal individuality can also be used in cases were the capture and handling of an animal is either logistically or ethically problematic. Many studies have suggested that vocal individuality can be used to count and monitor populations over time; however, few have explicitly tested the method in this role. In this review we discuss methods for extracting individuality information from vocalisations and techniques for using this to count and monitor populations over time. We present case studies in birds where vocal individuality has been applied to conservation and we discuss its role in mammals.

Cues to individual identity in songs of songbirds: testing general song characteristics in Chiffchaffs Phylloscopus collybita

“…Scientists have focused their attention on individual variability in bird vocalizations for decades, and many studies show individual variation in vocalizations in birds (Hutchison et al 1968;Thompson 1970;White et al 1970;Peake et al 1998;Lengagne 2001;Petrusková et al 2016). Studies on how individual identity is expressed in vocalizations are crucial for understanding the individual recognition process, but they are also important for practical situations, for example, this type of information might be eventually used as an alternative or complementary method for individual monitoring (Terry et al 2005;Laiolo et al 2007;Mennill 2011).…”

The use of bioacoustics in anuran taxonomy: theory, terminology, methods and recommendations for best practice

“…The individual call repertoire, variation, plasticity and change over time might be underestimated (Narins et al 2000;Jansen et al 2016b) and knowledge on the effective signal space of individuals, populations or species might be of taxonomic relevance. Automated recorders and signal processing are helpful in bioacoustical monitoring approaches (e.g., Terry et al 2005;Tripp & Otter 2006;Bardeli et al 2010;Laiolo 2010;Blumstein et al 2011) and thus in ecological studies and conservation. There are several recent works using modern passive recording devices for the estimation of biodiversity in holistic approaches (e.g., Sueur et al 2008b;Blumstein et al 2011;Depraetere et al 2012;Gasc et al 2013;Potamitis 2014; for a review see Obrist et al 2010).…”

Duet structure provides information about pair identity in the red-crowned crane (Grus japonensis)

“…All 15 species of the Gruidae family perform a unison call (Archibald 1976;Archibald and Lewis 1996), representing the duet by the definition of Farabaugh (1982), since ''both mates participate with evident temporal coordination.'' The crane duets are potentially appropriate as a non-invasive tool for call-based monitoring in nature: they are very loud and, thus, may be recorded from a distance (Terry et al 2005). Also, the grey-crowned crane (Balearica regulorum gibbericeps) and the common crane (Grus grus) duet structures have been shown to have higher intrapair than interpair similarity, which suggests the potential for the call-based identification of nesting pairs in nature (Budde 2001;Wessling 2000).…”