cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.825634.v1
title: Sound Finder: a new software approach for localizing animals recorded with a microphone array

description: Acoustic localization is a powerful technique for monitoring the positions, movements and behaviours of terrestrial animals. However, its prevalence in biological studies has been constrained by hardware and software that are custom-built, expensive and difficult to use. We recently helped to relieve the hardware constraint by describing a microphone array that is affordable, portable, easy to use and commercially available. Here, we help to relieve the software constraint by developing an acoustic localization program called “Sound Finder”, which is easy to use, freely available and accurate for a variety of animals and recording conditions. It runs in the free software environment R, and in spreadsheet programs such as Microsoft Excel and the open-source software LibreOffice. In this study, we describe how Sound Finder functions, and then test its accuracy by localizing natural sounds that were broadcast through loudspeakers and re-recorded with microphone arrays. We quantify Sound Finder's accuracy by comparing its location estimates with known loudspeaker locations and with output from other localization approaches. We show that Sound Finder generates accurate location estimates for a variety of animal sounds, microphone array configurations and environmental conditions. Furthermore, Sound Finder generates an error value that allows the user to assess its accuracy. In conclusion, Sound Finder provides accurate estimates of a vocalizing animal's location. It is easy to use, requires only widespread and affordable software and is freely available in a standard form as Supplementary material to this article.
DOI: 10.6084/m9.figshare.825631.v2
title: Ultrasonic communication in Gliridae (Rodentia): the hazel dormouse (<i>Muscardinus avellanarius</i>) as a case study

description: Ultrasonic vocalizations (USVs) have been detected in a range of small mammals, particularly rodents, and are associated not only with different social behaviours, e.g. sexual behaviour and aggression, but also with non-social behaviour in several species of mammals, including echolocation and as a by-product of respiration. Rodents in the Gliridae family are known to broadcast a variety of signals, but the behavioural relevance of the latter is poorly known. The aim of our study was to describe the vocal signals of <i>Muscardinus avellanarius</i> and to assess their function. By recording vocal and non-vocal behaviour of captive individuals in different social contexts, we demonstrate that <i>M. avellanarius</i> emits USVs and provide contextual evidence that such sounds are largely used for social communication. We identified six different vocalizations with an overall frequency range between 6.5 and 52.1 kHz, five out of six being ultrasonic (&gt;18 kHz). The vocal repertoire in <i>M. avellanarius</i> was associated with social behaviours, e.g. mother–infant reunion, isolation and paired opposite-sex courtship, all activities involving individuals that are out of mutual visual contact. We therefore infer that this repertoire constitutes a medium-distance (in the range of a few metres) communication system. Further research testing different social contexts both in nature and in captivity is needed for a more complete assessment of the vocal repertoire of this species and its function.
DOI: 10.6084/m9.figshare.825631.v1
title: Ultrasonic communication in Gliridae (Rodentia): the hazel dormouse (<i>Muscardinus avellanarius</i>) as a case study

description: Ultrasonic vocalizations (USVs) have been detected in a range of small mammals, particularly rodents, and are associated not only with different social behaviours, e.g. sexual behaviour and aggression, but also with non-social behaviour in several species of mammals, including echolocation and as a by-product of respiration. Rodents in the Gliridae family are known to broadcast a variety of signals, but the behavioural relevance of the latter is poorly known. The aim of our study was to describe the vocal signals of <i>Muscardinus avellanarius</i> and to assess their function. By recording vocal and non-vocal behaviour of captive individuals in different social contexts, we demonstrate that <i>M. avellanarius</i> emits USVs and provide contextual evidence that such sounds are largely used for social communication. We identified six different vocalizations with an overall frequency range between 6.5 and 52.1 kHz, five out of six being ultrasonic (&gt;18 kHz). The vocal repertoire in <i>M. avellanarius</i> was associated with social behaviours, e.g. mother–infant reunion, isolation and paired opposite-sex courtship, all activities involving individuals that are out of mutual visual contact. We therefore infer that this repertoire constitutes a medium-distance (in the range of a few metres) communication system. Further research testing different social contexts both in nature and in captivity is needed for a more complete assessment of the vocal repertoire of this species and its function.
DOI: 10.6084/m9.figshare.825632.v1
title: Characterization of Yellow Seahorse <i>Hippocampus kuda</i> feeding click sound signals in a laboratory environment: an application of probability density function and power spectral density analyses

description: Do the sounds generated by different-sized fish of different sexes differ from each other in temporal, spectral or intensity patterns? Such differences would enable the development of passive acoustic techniques to locate seahorses in open water bodies. On the basis of this perspective, we characterize and present in this study Yellow Seahorse <i>Hippocampus kuda</i> (Syngnathidae) feeding click sounds, recorded in a controlled laboratory environment. The characterization involved analysis of the “probability density function” (PDF) and the “power spectral density” (PSD) of the seahorse feeding click sound signals of different sizes and sexes. The PDF describes the general distribution of the magnitude of a random process, and such analysis, using recorded seahorse clicks, points towards a multimodal statistical distribution, which is the existence of more than one fitting component for the majority of seahorse click signals above the tank ambient noise level. This fact has been appraised towards the involvement of more than one process in the seahorse click signal generation mechanism. However, lack of prior knowledge about the individual PDF components of the data leads towards the mismatch between the data of PDFs. The PDF gives no information on the time and frequency content of the processes as provided by the PSD. Under such conditions, curve fitting of the “power law” expressions to the PSD functions estimates “slope” and “intercept” parameters of the seahorse click signal. Striking differences in the feeding click characteristics of various sizes of the <i>H. kuda</i> and between the sexes were discernable based on the clustering pattern among the estimated “slope” and “intercept” parameters. Further studies using the seahorse body sizes and weight (wet) with respect to the peak frequencies estimated from the PSD distribution show results equivalent to those from previous studies.
DOI: 10.6084/m9.figshare.825629
title: Ultrasonic reverse stridulation in the spider-like katydid <i>Arachnoscelis</i> (Orthoptera: Listrosceledinae)

description: This paper illustrates the biomechanics of sound production in the neotropical predaceous katydid <i>Arachnoscelis arachnoides</i> (Insecta: Orthoptera: Tettigoniidae). Described and previously known from only one male specimen, this genus of predaceous katydids resembles spiders in their general body appearance. To call distant females, male katydids produce songs by stridulation where one forewing possessing a sclerotized file rubs against a row of teeth (scraper) on the other wing. In most katydid species, the songs are produced during the wing-closing phase of the stridulation. Morphological comparative studies of the stridulatory apparatus of the type specimen of <i>Arachnoscelis arachnoides</i> and males of other closely related species suggest that this insect sings with a frequency of ca. 80 kHz to attract conspecific females. We found an abundant population of <i>A. arachnoides</i> in Central Northeast of Colombia and undertook a complete analysis of the biomechanics of stridulation in this species. Using ultrasound-sensitive equipment and high-speed video, we determined that male <i>A. arachnoides</i> sing at ca. 74 kHz and use elastic energy and wing deformation to reach such ultrasonic frequencies. In contrast to most katydids, males of this species produce their calls during the opening phase of the wing; this form of stridulation is discussed.
DOI: 10.6084/m9.figshare.825630.v1
title: The vocal repertoire of infant giant pandas (<i>Ailuropoda melanoleuca</i>)

description: Infant giant pandas (<i>Ailuropoda melanoleuca</i>) are highly vocal during the first few weeks of their life. Despite this, no previous studies have attempted to systematically categorize infant giant panda vocalizations into different call types. In this study, we used acoustic and video analyses to split infant giant panda vocalizations into three distinct call types based on their acoustic structure as well as their use in different behavioural contexts. A discriminant functions analysis on the acoustic variables confirmed our initial subjective classification of 281 vocalizations into three call types: the harsh sounding “squawk”, the high-pitched “squall” and the pulsed “croak”. Based on the observed spectral acoustic characteristics, none of these three infant call types appears to be a precursor of an adult giant panda vocalization. In addition, individual call types could not be assigned to specific recording contexts. These findings suggest that infant giant panda vocalizations convey information about a cub's distress and need, rather than being tied to specific contexts of emission. Our objective demonstration that infant giant pandas have three basic call types provides a foundation for future studies of vocal ontogeny in this highly endangered species.
DOI: 10.6084/m9.figshare.825627
title: A weak individual signature might not allow chick call recognition by parent Stone Curlews <i>Burhinus oedicnemus</i>

description: Offspring recognition has been confirmed in many bird species, and vocal signatures appear to be its major component. Up to now most studies dealt with colonial species, but recent findings indicate that similar recognition is also present in non-colonial birds. By integrating spectrographic analysis and playback experiments, we investigated for the first time parent–offspring vocal recognition in the Stone Curlew (<i>Burhinus oedicnemus</i>), a highly vocal, crepuscular-nocturnal species that usually rears a maximum of two precocial and nidifugous chicks. Even though the species is usually non-colonial and non-cooperative, in Taro River Regional Park, Parma, Italy, breeding territories are densely packed with distances between simultaneously active nests as close as 40 m, which creates the possibility that chicks might be exchanged. Our analysis identified two main vocalizations in the chick call repertoire: (1) the S-call, a brief strangled soft sound often uttered when parents and chicks were at close quarters; and (2) the C-call, a chirping sound with a complex structure, which seems to be a long-distance contact vocalization. Our acoustic analysis showed that, even though the structure was remarkably different between chicks, C-calls were an unreliable individual signature given their high intra-individual variability. This was confirmed by playback experiments. Indeed, when presented with simulated C-calling chicks, adults approached both their own and foreign chicks with equal responses. These results suggest that parent Stone Curlews are unable to recognize their offspring by voice. Furthermore, experiments are needed to test whether the chicks are able to recognize their parents' voice and, more generally, to understand the details of parent–offspring communication in this species.
DOI: 10.6084/m9.figshare.825630.v3
title: The vocal repertoire of infant giant pandas (<i>Ailuropoda melanoleuca</i>)

description: Infant giant pandas (<i>Ailuropoda melanoleuca</i>) are highly vocal during the first few weeks of their life. Despite this, no previous studies have attempted to systematically categorize infant giant panda vocalizations into different call types. In this study, we used acoustic and video analyses to split infant giant panda vocalizations into three distinct call types based on their acoustic structure as well as their use in different behavioural contexts. A discriminant functions analysis on the acoustic variables confirmed our initial subjective classification of 281 vocalizations into three call types: the harsh sounding “squawk”, the high-pitched “squall” and the pulsed “croak”. Based on the observed spectral acoustic characteristics, none of these three infant call types appears to be a precursor of an adult giant panda vocalization. In addition, individual call types could not be assigned to specific recording contexts. These findings suggest that infant giant panda vocalizations convey information about a cub's distress and need, rather than being tied to specific contexts of emission. Our objective demonstration that infant giant pandas have three basic call types provides a foundation for future studies of vocal ontogeny in this highly endangered species.
DOI: 10.6084/m9.figshare.825629.v2
title: Ultrasonic reverse stridulation in the spider-like katydid <i>Arachnoscelis</i> (Orthoptera: Listrosceledinae)

description: This paper illustrates the biomechanics of sound production in the neotropical predaceous katydid <i>Arachnoscelis arachnoides</i> (Insecta: Orthoptera: Tettigoniidae). Described and previously known from only one male specimen, this genus of predaceous katydids resembles spiders in their general body appearance. To call distant females, male katydids produce songs by stridulation where one forewing possessing a sclerotized file rubs against a row of teeth (scraper) on the other wing. In most katydid species, the songs are produced during the wing-closing phase of the stridulation. Morphological comparative studies of the stridulatory apparatus of the type specimen of <i>Arachnoscelis arachnoides</i> and males of other closely related species suggest that this insect sings with a frequency of ca. 80 kHz to attract conspecific females. We found an abundant population of <i>A. arachnoides</i> in Central Northeast of Colombia and undertook a complete analysis of the biomechanics of stridulation in this species. Using ultrasound-sensitive equipment and high-speed video, we determined that male <i>A. arachnoides</i> sing at ca. 74 kHz and use elastic energy and wing deformation to reach such ultrasonic frequencies. In contrast to most katydids, males of this species produce their calls during the opening phase of the wing; this form of stridulation is discussed.
DOI: 10.6084/m9.figshare.825630.v2
title: The vocal repertoire of infant giant pandas (<i>Ailuropoda melanoleuca</i>)

description: Infant giant pandas (<i>Ailuropoda melanoleuca</i>) are highly vocal during the first few weeks of their life. Despite this, no previous studies have attempted to systematically categorize infant giant panda vocalizations into different call types. In this study, we used acoustic and video analyses to split infant giant panda vocalizations into three distinct call types based on their acoustic structure as well as their use in different behavioural contexts. A discriminant functions analysis on the acoustic variables confirmed our initial subjective classification of 281 vocalizations into three call types: the harsh sounding “squawk”, the high-pitched “squall” and the pulsed “croak”. Based on the observed spectral acoustic characteristics, none of these three infant call types appears to be a precursor of an adult giant panda vocalization. In addition, individual call types could not be assigned to specific recording contexts. These findings suggest that infant giant panda vocalizations convey information about a cub's distress and need, rather than being tied to specific contexts of emission. Our objective demonstration that infant giant pandas have three basic call types provides a foundation for future studies of vocal ontogeny in this highly endangered species.
DOI: 10.6084/m9.figshare.825625
title: Individual identity, song repertoire and duet function in the Crimson-breasted Shrike (<i>Laniarius atrococcineus</i>)

description: Avian vocal duets are joint displays where paired birds produce temporally and structurally coordinated vocalisations. Duets show great variety in form that can reflect different functions, such as mate guarding, mutual recognition, pair bond maintenance or territory defence. By describing the structure of duets and singing behaviour, we can investigate whether these signals are based on cooperation or conflict and which functions they might have. Here we describe the singing behaviour and song repertoire of the Crimson-breasted Shrike in the Kalahari Desert, and assess four main hypotheses proposed for the function of duets. We found that Crimson-breasted Shrikes have a sex-specific repertoire, and the individuality of males, females and pairs is expressed acoustically. Differences in vocal strategies between the sexes indicate male mate guarding as one possible function. Temporal coordination is high and duetters follow strict codes, suggesting that duetting could be a cooperative endeavour in this species. The observed duetting behaviour is also consistent with the predictions for mutual recognition because each bird has its individual vocal characteristics that are consistent over time. Our results provide no support for the hypothesis that duets serve pair bond maintenance in this species as no partner-directed adjustment of temporal coordination took place.
DOI: 10.6084/m9.figshare.825627.v1
title: A weak individual signature might not allow chick call recognition by parent Stone Curlews <i>Burhinus oedicnemus</i>

description: Offspring recognition has been confirmed in many bird species, and vocal signatures appear to be its major component. Up to now most studies dealt with colonial species, but recent findings indicate that similar recognition is also present in non-colonial birds. By integrating spectrographic analysis and playback experiments, we investigated for the first time parent–offspring vocal recognition in the Stone Curlew (<i>Burhinus oedicnemus</i>), a highly vocal, crepuscular-nocturnal species that usually rears a maximum of two precocial and nidifugous chicks. Even though the species is usually non-colonial and non-cooperative, in Taro River Regional Park, Parma, Italy, breeding territories are densely packed with distances between simultaneously active nests as close as 40 m, which creates the possibility that chicks might be exchanged. Our analysis identified two main vocalizations in the chick call repertoire: (1) the S-call, a brief strangled soft sound often uttered when parents and chicks were at close quarters; and (2) the C-call, a chirping sound with a complex structure, which seems to be a long-distance contact vocalization. Our acoustic analysis showed that, even though the structure was remarkably different between chicks, C-calls were an unreliable individual signature given their high intra-individual variability. This was confirmed by playback experiments. Indeed, when presented with simulated C-calling chicks, adults approached both their own and foreign chicks with equal responses. These results suggest that parent Stone Curlews are unable to recognize their offspring by voice. Furthermore, experiments are needed to test whether the chicks are able to recognize their parents' voice and, more generally, to understand the details of parent–offspring communication in this species.
DOI: 10.6084/m9.figshare.825625.v1
title: Individual identity, song repertoire and duet function in the Crimson-breasted Shrike (<i>Laniarius atrococcineus</i>)

description: Avian vocal duets are joint displays where paired birds produce temporally and structurally coordinated vocalisations. Duets show great variety in form that can reflect different functions, such as mate guarding, mutual recognition, pair bond maintenance or territory defence. By describing the structure of duets and singing behaviour, we can investigate whether these signals are based on cooperation or conflict and which functions they might have. Here we describe the singing behaviour and song repertoire of the Crimson-breasted Shrike in the Kalahari Desert, and assess four main hypotheses proposed for the function of duets. We found that Crimson-breasted Shrikes have a sex-specific repertoire, and the individuality of males, females and pairs is expressed acoustically. Differences in vocal strategies between the sexes indicate male mate guarding as one possible function. Temporal coordination is high and duetters follow strict codes, suggesting that duetting could be a cooperative endeavour in this species. The observed duetting behaviour is also consistent with the predictions for mutual recognition because each bird has its individual vocal characteristics that are consistent over time. Our results provide no support for the hypothesis that duets serve pair bond maintenance in this species as no partner-directed adjustment of temporal coordination took place.
DOI: 10.6084/m9.figshare.825629.v1
title: Ultrasonic reverse stridulation in the spider-like katydid <i>Arachnoscelis</i> (Orthoptera: Listrosceledinae)

description: This paper illustrates the biomechanics of sound production in the neotropical predaceous katydid <i>Arachnoscelis arachnoides</i> (Insecta: Orthoptera: Tettigoniidae). Described and previously known from only one male specimen, this genus of predaceous katydids resembles spiders in their general body appearance. To call distant females, male katydids produce songs by stridulation where one forewing possessing a sclerotized file rubs against a row of teeth (scraper) on the other wing. In most katydid species, the songs are produced during the wing-closing phase of the stridulation. Morphological comparative studies of the stridulatory apparatus of the type specimen of <i>Arachnoscelis arachnoides</i> and males of other closely related species suggest that this insect sings with a frequency of ca. 80 kHz to attract conspecific females. We found an abundant population of <i>A. arachnoides</i> in Central Northeast of Colombia and undertook a complete analysis of the biomechanics of stridulation in this species. Using ultrasound-sensitive equipment and high-speed video, we determined that male <i>A. arachnoides</i> sing at ca. 74 kHz and use elastic energy and wing deformation to reach such ultrasonic frequencies. In contrast to most katydids, males of this species produce their calls during the opening phase of the wing; this form of stridulation is discussed.