Vocal discrimination of African lions and its potential for collar-free tracking

Wijers, Matthew; Trethowan, Paul; Preez, Byron du; Chamaillé‐Jammes, Simon; Loveridge, Andrew J.; Macdonald, David W.; Markham, Andrew

doi:10.1080/09524622.2020.1829050

Cited by 14 publications

(14 citation statements)

References 58 publications

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“…Interestingly, some whoop types and some individuals were more difficult than others to categorize correctly; however, we cannot disentangle whether this is a product of our dataset or whether instead it represents meaningful differences among whoop types (as in lion roar types [81]) and individual voices. ‘A’ type whoops may be more easily classified because they are over-represented in the dataset or ‘A’ whoops may be more common within whoop bouts because their protracted CF portion is a good indicator of individual identity (figure 4).…”

Section: Discussionmentioning

confidence: 99%

Long-distance vocalizations of spotted hyenas contain individual, but not group, signatures

et al. 2022

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In animal societies, identity signals are common, mediate interactions within groups, and allow individuals to discriminate group-mates from out-group competitors. However, individual recognition becomes increasingly challenging as group size increases and as signals must be transmitted over greater distances. Group vocal signatures may evolve when successful in-group/out-group distinctions are at the crux of fitness-relevant decisions, but group signatures alone are insufficient when differentiated within-group relationships are important for decision-making. Spotted hyenas are social carnivores that live in stable clans of less than 125 individuals composed of multiple unrelated matrilines. Clan members cooperate to defend resources and communal territories from neighbouring clans and other mega carnivores; this collective defence is mediated by long-range (up to 5 km range) recruitment vocalizations, called whoops. Here, we use machine learning to determine that spotted hyena whoops contain individual but not group signatures, and that fundamental frequency features which propagate well are critical for individual discrimination. For effective clan-level cooperation, hyenas face the cognitive challenge of remembering and recognizing individual voices at long range. We show that serial redundancy in whoop bouts increases individual classification accuracy and thus extended call bouts used by hyenas probably evolved to overcome the challenges of communicating individual identity at long distance.

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Section: Discussionmentioning

confidence: 99%

Long-distance vocalizations of spotted hyenas contain individual, but not group, signatures

et al. 2022

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“…Potentially, recognition of caller sex and individuality by voice may help avoiding undesirable conflicts between competing social units of cheetahs, or, otherwise, to help searching mating partners (Wachter et al, 2018). Previously, social regulation based on individual and sex recognition by distance calls was reported for free‐ranging lions Panthera leo (McComb et al, 1993; Wijers et al, 2021). In captive non‐domesticated felids aside cheetahs, vocal correlates of caller identity were found in the long‐distance calls of tigers Panthera tigris (Ji et al, 2013) and male Eurasian lynxes Lynx lynx (Rutovskaya et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…Previously, social regulation based on individual and sex recognition by distance calls was reported for free-ranging lions Panthera leo (McComb et al, 1993;Wijers et al, 2021). In captive non-domesticated felids aside cheetahs, vocal correlates of caller identity were found in the long-distance calls of tigers Panthera tigris (Ji et al, 2013) and male Eurasian lynxes Lynx lynx (Rutovskaya et al, 2009).…”

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confidence: 95%

Advertising sex and individual identity by long‐distance chirps in wild‐living mature cheetahs (Acinonyx jubatus)

et al. 2023

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Adult cheetahs (Acinonyx jubatus) use long‐distance chirps for calling toward coalition partners (males), mates (both sexes), and cubs (females). Previously, these vocalizations were only investigated in captivity. This study estimates individual and sex‐related acoustic variation of the long‐distance chirps of 20 mature cheetahs (eight males and 12 females older than 4 years) in their natural habitats in Kenya. Male chirps were longer in duration and lower in the peak frequency and all fundamental frequency variables than female chirps. The average value for assignment of the chirps to correct sex with Discriminant Function Analysis (DFA) of 93.8% was significantly higher than by‐chance level of 52.9%. The average value of correct assignment of the chirps to individual with DFA was 79.5%, which was significantly higher than the level by chance of 14.8%. For 10 cheetahs recorded twice with time space of one or 2 years, DFA showed high values of correct assignment of the chirps to individual for both years (91.4% in the first year and 83.9% in the second year of recording), but cross‐validation of the chirps recorded in the second year by discriminant functions created for the chirps of the first year showed a dramatic decrease of correct assignment to the level expected by chance (27.2%). We discuss that long‐distance chirps of wild mature cheetahs provide reliable cues to sex and may also encode caller individuality, although this is not stable over time.

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“…The lower costs, energy consumption, and required storing capacity of accelerometers (Brown et al, 2013; Hughey et al, 2018; Korpela et al, 2020) result in lower weight and smaller‐sized devices with extended logging durations (several days or weeks; Brown et al, 2013). Nonetheless, further investigation of the use of accelerometers in the study of vocal communication has received limited attention (Naito et al, 2010; Oestreich et al, 2020; Saddler et al, 2017; Stimpert et al, 2020; Wijers et al, 2020) and has—to the best of our knowledge—only been applied in two species of bustards which perform booming calls, associated with excessive head movements (little bustards Tetrax , Gudka et al, 2019; African houbara bustards Chlamydotis undulata , Alonso et al, 2021). The limited adoption of accelerometers in vocal studies is possibly due to the difficulty of assigning accelerometer data to different behaviors in free‐roaming animals (Alonso et al, 2021; Brown et al, 2013; Nathan et al, 2012; Shamoun‐Baranes et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Quantifying song behavior in a free‐living, light‐weight, mobile bird using accelerometers

Eisenring

Eens

Pradervand

et al. 2022

Ecology and Evolution

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To acquire a fundamental understanding of animal communication, continuous observations in a natural setting and at an individual level are required. Whereas the use of animal‐borne acoustic recorders in vocal studies remains challenging, light‐weight accelerometers can potentially register individuals’ vocal output when this coincides with body vibrations. We collected one‐dimensional accelerometer data using light‐weight tags on a free‐living, crepuscular bird species, the European Nightjar (Caprimulgus europaeus). We developed a classification model to identify four behaviors (rest, sing, fly, and leap) from accelerometer data and, for the purpose of this study, validated the classification of song behavior. Male nightjars produce a distinctive “churring” song while they rest on a stationary song post. We expected churring to be associated with body vibrations (i.e., medium‐amplitude body acceleration), which we assumed would be easy to distinguish from resting (i.e., low‐amplitude body acceleration). We validated the classification of song behavior using simultaneous GPS tracking data (i.e., information on individuals’ movement and proximity to audio recorders) and vocal recordings from stationary audio recorders at known song posts of one tracked individual. Song activity was detected by the classification model with an accuracy of 92%. Beyond a threshold of 20 m from the audio recorders, only 8% of the classified song bouts were recorded. The duration of the detected song activity (i.e., acceleration data) was highly correlated with the duration of the simultaneously recorded song bouts (correlation coefficient = 0.87, N = 10, S = 21.7, p = .001). We show that accelerometer‐based identification of vocalizations could serve as a promising tool to study communication in free‐living, small‐sized birds and demonstrate possible limitations of audio recorders to investigate individual‐based variation in song behavior.

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Vocal discrimination of African lions and its potential for collar-free tracking

Cited by 14 publications

References 58 publications

Long-distance vocalizations of spotted hyenas contain individual, but not group, signatures

Long-distance vocalizations of spotted hyenas contain individual, but not group, signatures

Advertising sex and individual identity by long‐distance chirps in wild‐living mature cheetahs (Acinonyx jubatus)

Quantifying song behavior in a free‐living, light‐weight, mobile bird using accelerometers

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