Geographical variation in squirrel mating calls and their recognition limits in the widely distributed species complex

Tamura, Noriko; Boonkhaw, Phadet; Prayoon, Umphornpimon; Phan, Quoc Toan; Yu, Pei; Liu, Xingyue; Hayashi, Fumio

doi:10.1007/s00265-021-03022-3

Cited by 3 publications

(3 citation statements)

References 79 publications

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“…Another factor that can impact classifier outcomes is geographic location. Many species exhibit geographic variation in their signals [90][91][92][93], and different locations often comprise different assemblages of species. Because of these factors, a classifier trained using data from one location will not necessarily be accurate when applied to data collected in a different location.…”

Section: Species Identificationmentioning

confidence: 99%

A Collection of Best Practices for the Collection and Analysis of Bioacoustic Data

et al. 2022

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The field of bioacoustics is rapidly developing and characterized by diverse methodologies, approaches and aims. For instance, bioacoustics encompasses studies on the perception of pure tones in meticulously controlled laboratory settings, documentation of species’ presence and activities using recordings from the field, and analyses of circadian calling patterns in animal choruses. Newcomers to the field are confronted with a vast and fragmented literature, and a lack of accessible reference papers or textbooks. In this paper we contribute towards filling this gap. Instead of a classical list of “dos” and “don’ts”, we review some key papers which, we believe, embody best practices in several bioacoustic subfields. In the first three case studies, we discuss how bioacoustics can help identify the ‘who’, ‘where’ and ‘how many’ of animals within a given ecosystem. Specifically, we review cases in which bioacoustic methods have been applied with success to draw inferences regarding species identification, population structure, and biodiversity. In fourth and fifth case studies, we highlight how structural properties in signal evolution can emerge via ecological constraints or cultural transmission. Finally, in a sixth example, we discuss acoustic methods that have been used to infer predator–prey dynamics in cases where direct observation was not feasible. Across all these examples, we emphasize the importance of appropriate recording parameters and experimental design. We conclude by highlighting common best practices across studies as well as caveats about our own overview. We hope our efforts spur a more general effort in standardizing best practices across the subareas we’ve highlighted in order to increase compatibility among bioacoustic studies and inspire cross-pollination across the discipline.

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Section: Species Identificationmentioning

confidence: 99%

A Collection of Best Practices for the Collection and Analysis of Bioacoustic Data

et al. 2022

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“…Second, playbacks can be carried out with modified calls in which features potentially used for individual recognition are altered one by one, while keeping the rest constant. These modified calls can then be played to the animals to assess whether these changes impair recognition (Charrier et al ., 2003; Tamura et al ., 2021). If recognition is impaired by the modification of a parameter, this suggests that it is used for recognition.…”

Section: Introductionmentioning

confidence: 99%

Goat kid recognition of their mothers’ calls is not impacted by changes in source-filter parameters

Perroux

McElligott

Briefer

2022

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Features varying more between than within individuals are usually considered as potential cues for individual recognition. According to the source-filter theory of vocal production, the fundamental frequency of mammal’s vocalisations depends on the characteristics of the vocal folds, while formants are determined by the characteristics of the vocal tract. Goat mothers and their kids (Capra hircus) display mutual recognition, and both source-related parameters (F0) and filter-related ones (formants) have been shown to be individualised in their vocalisations. Here, we aimed to identify if these parameters (source-related parameters (F0) and/or filter vocal parameters) are used by goat kids to recognise their mother’s vocalisations. To this aim, we used an algorithm to modify either F0 or formants of the calls of goat mothers to different degrees (within or exceeding the range of natural intra-individual variability), and we played back these modified calls to their kids. We did not observe any difference in the kid reactions to the modified maternal vocalisations and to the natural calls. We suggest that either: (i) fundamental frequency and formants are not involved in maternal recognition in goats; (ii) goat kids have a tolerance for variation when recognising their mother’s calls that exceeds the shifts we performed; (iii) goat maternal recognition is based on other vocal features than those tested here, or (iv) goat kid maternal recognition is based on a combination of different features and might be more flexible than previously thought, such that when one main feature is modified, kids focus on other features.

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“…Second, playbacks can be carried out with modified calls in which features potentially used for individual recognition are altered one by one, while keeping the rest constant. These modified calls can then be played to the animals to assess whether these changes impair recognition (Charrier et al., 2003; Tamura et al., 2021). If recognition is impaired by the modification of a parameter, this suggests that it is used for recognition.…”

Section: Introductionmentioning

confidence: 99%

Goat kid recognition of their mothers' calls is not impacted by changes in fundamental frequency or formants

2022

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Features varying more between than within individuals are considered as potential cues for individual recognition. According to the source‐filter theory of vocal production, the fundamental frequency of mammals' vocalizations depends on the characteristics of vocal folds, while Formants are determined by the characteristics of the vocal tract. Goat mothers and their kids (Capra hircus) display mutual recognition, and both source‐related parameters (f0) and filter‐related ones (Formants) have been shown to be individualized. Here, we aimed to identify if f0 and Formants are used by goat kids to recognize their mother's vocalizations. To do this, we independently modified these parameters in calls of goat mothers to different degrees (within or exceeding the range of natural intra‐individual variability), and we played back these modified calls to their kids. We found no effect of f0 or Formants modification on the kids' reactions. Further analyses revealed that goat kids emitted fewer calls when modifications to f0 resulted in higher values of the first energy quartile, suggesting a role of the distribution of energy in the spectrum in maternal recognition. We propose that either: (i) f0 and Formants are not involved in goats' maternal recognition; (ii) goat kids have a tolerance for variation when recognizing their mother's calls that exceeds the performed shifts in these parameters; or (iii) goat kid maternal recognition is based on a combination of features and might be more flexible than previously thought, such that when one feature is modified, kids focus on other features. The effect of the spectral energy distribution modification on the kid responses, which depends both on f0 and Formant heights, suggests that (iii) is a likely explanation. Our findings support the hypothesis of complex individual acoustic recognition from the early stages of development in ungulates.

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Geographical variation in squirrel mating calls and their recognition limits in the widely distributed species complex

Cited by 3 publications

References 79 publications

A Collection of Best Practices for the Collection and Analysis of Bioacoustic Data

A Collection of Best Practices for the Collection and Analysis of Bioacoustic Data

Goat kid recognition of their mothers’ calls is not impacted by changes in source-filter parameters

Goat kid recognition of their mothers' calls is not impacted by changes in fundamental frequency or formants

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