Pub Date : 2023-02-09DOI: 10.1080/09524622.2023.2172080
C. Snell, M. Reudink, K. Otter
ABSTRACT Urban noise can disrupt avian communication networks, resulting in reduced communication among individuals. Mountain chickadees alter their vocalisations in areas of high ambient noise; however, it is unknown how audible their signals are within the nest cavity, where the female remains during dawn signalling. To test the relative audibility of songs within the nest box of urban and rural chickadees, we conducted a playback experiment directed at empty nest boxes using an autonomous recording unit above the box with external microphones and an internal microphone inside the nest box. We placed a speaker 25-75 m from the nest box and played two playback files of mountain chickadee songs – one with added noise and one without. Songs had a higher signal-to-noise ratio (SNR) in rural habitats and in ‘Without Added Noise’ treatments, however, SNR decreased with increasing distance from the nest box. The lower frequency song notes had a lower SNR inside the nest in both treatment types. As expected, noise and distance resulted in decreased SNR of chickadee songs within the nest cavity. These findings suggest a possible constraint in urban birds requiring them to reduce their distance from the nest to ensure audibility to the female while in noise.
{"title":"Hard of hearing: the effect of distance and experimental noise on mountain chickadee song transmission","authors":"C. Snell, M. Reudink, K. Otter","doi":"10.1080/09524622.2023.2172080","DOIUrl":"https://doi.org/10.1080/09524622.2023.2172080","url":null,"abstract":"ABSTRACT Urban noise can disrupt avian communication networks, resulting in reduced communication among individuals. Mountain chickadees alter their vocalisations in areas of high ambient noise; however, it is unknown how audible their signals are within the nest cavity, where the female remains during dawn signalling. To test the relative audibility of songs within the nest box of urban and rural chickadees, we conducted a playback experiment directed at empty nest boxes using an autonomous recording unit above the box with external microphones and an internal microphone inside the nest box. We placed a speaker 25-75 m from the nest box and played two playback files of mountain chickadee songs – one with added noise and one without. Songs had a higher signal-to-noise ratio (SNR) in rural habitats and in ‘Without Added Noise’ treatments, however, SNR decreased with increasing distance from the nest box. The lower frequency song notes had a lower SNR inside the nest in both treatment types. As expected, noise and distance resulted in decreased SNR of chickadee songs within the nest cavity. These findings suggest a possible constraint in urban birds requiring them to reduce their distance from the nest to ensure audibility to the female while in noise.","PeriodicalId":55385,"journal":{"name":"Bioacoustics-The International Journal of Animal Sound and Its Recording","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49397993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-30DOI: 10.1080/09524622.2023.2170469
Robyn Manuel, Tarné Johannes, Rekha Sathyan, V. Couldridge
ABSTRACT Ecological interactions, including competition, predation, and environmental conditions, may significantly impact acoustic signalling behaviour. Here we characterise nocturnal signalling patterns in the bladder grasshopper Bullacris unicolor and relate this to biotic and abiotic factors, thus providing insights into ecological drivers of acoustic signalling behaviour. Passive acoustic recorders monitored nocturnal calling activity of the focal species, competitors, and predatory bats across the distribution of B. unicolor. Results indicate that B. unicolor calls preferentially at certain times of the night, but that peak activity period varies across the geographic range. There was a strong relationship between B. unicolor activity and bat activity. Bullacris unicolor populations further north showed an overall avoidance of bat echolocation call period, whereas further south an overlapping of call periods between B. unicolor and bat echolocation was observed. Bats at northern sites showed a distinct activity period early in the night and B. unicolor may thus reduce predation risk by shifting signalling activity to later in the night. In contrast, bats were active throughout the night at southern sites and B. unicolor did not delay calling activity in this region of its distribution, although the species did shift signalling slightly to reduce peak overlap with co-existing pneumorid species.
{"title":"Temporal partitioning of Bullacris unicolor (Orthoptera: Pneumoridae) calling activity to avoid predation","authors":"Robyn Manuel, Tarné Johannes, Rekha Sathyan, V. Couldridge","doi":"10.1080/09524622.2023.2170469","DOIUrl":"https://doi.org/10.1080/09524622.2023.2170469","url":null,"abstract":"ABSTRACT Ecological interactions, including competition, predation, and environmental conditions, may significantly impact acoustic signalling behaviour. Here we characterise nocturnal signalling patterns in the bladder grasshopper Bullacris unicolor and relate this to biotic and abiotic factors, thus providing insights into ecological drivers of acoustic signalling behaviour. Passive acoustic recorders monitored nocturnal calling activity of the focal species, competitors, and predatory bats across the distribution of B. unicolor. Results indicate that B. unicolor calls preferentially at certain times of the night, but that peak activity period varies across the geographic range. There was a strong relationship between B. unicolor activity and bat activity. Bullacris unicolor populations further north showed an overall avoidance of bat echolocation call period, whereas further south an overlapping of call periods between B. unicolor and bat echolocation was observed. Bats at northern sites showed a distinct activity period early in the night and B. unicolor may thus reduce predation risk by shifting signalling activity to later in the night. In contrast, bats were active throughout the night at southern sites and B. unicolor did not delay calling activity in this region of its distribution, although the species did shift signalling slightly to reduce peak overlap with co-existing pneumorid species.","PeriodicalId":55385,"journal":{"name":"Bioacoustics-The International Journal of Animal Sound and Its Recording","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46182767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-09DOI: 10.1080/09524622.2022.2128876
Melanie L. Low, Veronica L. Bura, J. Yack
ABSTRACT Silk and hawk moth caterpillars produce a variety of defence sounds described as clicking, chirping, whistling, and vocalising. Such diversity provides opportunity to test hypotheses on the functions and evolution of insect defence sounds using comparative analyses. A key step to conducting comparative analyses is to categorise different phenotypes. Here, we describe mandible sounds of 20 species of late instar Bombycoidea caterpillars and establish objective criteria for differentiating between sound-producing mechanisms. First, we assess how the two mandibular mechanisms – clicking and chirping – differ from one another using two reference species: Antheraea polyphemus (clicker) and Saturnia pyri (chirper). In these references, clicks are produced by ridged and serrated mandibles and have short duration units with few pulses, whereas chirps are produced by scalloped mandibles and have longer duration units with more pulses. Second, we characterise acoustic and morphological traits of 18 additional species. These are categorised as clickers (13 species), chirpers (4 species), or other (1 species) using diagnostic features identified from the reference species. Third, these categorisations are tested using a predictive logistic regression model. The results of this study contribute to our understanding of acoustically mediated defences in caterpillars and provide necessary criteria for conducting further comparative studies.
{"title":"Caterpillar sonic defences: mechanisms and diversity of mandible stridulation in silk and hawk moth (Bombycoidea) larvae","authors":"Melanie L. Low, Veronica L. Bura, J. Yack","doi":"10.1080/09524622.2022.2128876","DOIUrl":"https://doi.org/10.1080/09524622.2022.2128876","url":null,"abstract":"ABSTRACT Silk and hawk moth caterpillars produce a variety of defence sounds described as clicking, chirping, whistling, and vocalising. Such diversity provides opportunity to test hypotheses on the functions and evolution of insect defence sounds using comparative analyses. A key step to conducting comparative analyses is to categorise different phenotypes. Here, we describe mandible sounds of 20 species of late instar Bombycoidea caterpillars and establish objective criteria for differentiating between sound-producing mechanisms. First, we assess how the two mandibular mechanisms – clicking and chirping – differ from one another using two reference species: Antheraea polyphemus (clicker) and Saturnia pyri (chirper). In these references, clicks are produced by ridged and serrated mandibles and have short duration units with few pulses, whereas chirps are produced by scalloped mandibles and have longer duration units with more pulses. Second, we characterise acoustic and morphological traits of 18 additional species. These are categorised as clickers (13 species), chirpers (4 species), or other (1 species) using diagnostic features identified from the reference species. Third, these categorisations are tested using a predictive logistic regression model. The results of this study contribute to our understanding of acoustically mediated defences in caterpillars and provide necessary criteria for conducting further comparative studies.","PeriodicalId":55385,"journal":{"name":"Bioacoustics-The International Journal of Animal Sound and Its Recording","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46161882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-28DOI: 10.1080/09524622.2022.2122560
E. Girola, R. Dunlop, M. Noad
ABSTRACT The songs produced by male humpback whales are believed to be a reproductive display shared by all singers within the same population. Ocean noise can interfere with the transmission of acoustic signals such as humpback whale songs. However, humpback whales evolved in an environment characterised by variable levels of noise generated by natural sources. This study investigates whether singing males compensate for natural noise by changing the characteristics of their sounds. Songs were recorded off eastern Australia during periods of time when the soundscape was dominated by natural noise. Source level, peak frequency and duration were measured for 2,318 song units from 19 singers. Source levels were positively correlated with noise levels, while there was no correlation between the peak frequency or duration of the units and noise levels. Our study shows that male humpback whales increase the source level of their units in response to increasing natural noise, i.e. they have a Lombard response, but they do not modify their spectral or temporal characteristics. This suggests that the need to adhere to the shared repertoire prevents changes to distinctive features of song units, i.e. frequency and duration, however, vocal plasticity allows adjusting source levels to the environmental conditions.
{"title":"Singing in a noisy ocean: vocal plasticity in male humpback whales","authors":"E. Girola, R. Dunlop, M. Noad","doi":"10.1080/09524622.2022.2122560","DOIUrl":"https://doi.org/10.1080/09524622.2022.2122560","url":null,"abstract":"ABSTRACT The songs produced by male humpback whales are believed to be a reproductive display shared by all singers within the same population. Ocean noise can interfere with the transmission of acoustic signals such as humpback whale songs. However, humpback whales evolved in an environment characterised by variable levels of noise generated by natural sources. This study investigates whether singing males compensate for natural noise by changing the characteristics of their sounds. Songs were recorded off eastern Australia during periods of time when the soundscape was dominated by natural noise. Source level, peak frequency and duration were measured for 2,318 song units from 19 singers. Source levels were positively correlated with noise levels, while there was no correlation between the peak frequency or duration of the units and noise levels. Our study shows that male humpback whales increase the source level of their units in response to increasing natural noise, i.e. they have a Lombard response, but they do not modify their spectral or temporal characteristics. This suggests that the need to adhere to the shared repertoire prevents changes to distinctive features of song units, i.e. frequency and duration, however, vocal plasticity allows adjusting source levels to the environmental conditions.","PeriodicalId":55385,"journal":{"name":"Bioacoustics-The International Journal of Animal Sound and Its Recording","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49555559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-19DOI: 10.1080/09524622.2022.2122561
Katie A. Kowarski, S. Cerchio, H. Whitehead, Danielle M. Cholewiak, H. Moors-Murphy
ABSTRACT The use of song as a reproductive display is common in the animal kingdom; however, for many taxa, little is known of song ontogeny. Male humpback whales produce elaborate songs on low latitude breeding grounds in winter and begin to sing on high latitude feeding grounds in late summer, yet songs from the two locations are rarely compared. Seasonal song ontogeny in western North Atlantic humpback whales was explored by comparing songs recorded in high latitude feeding grounds (Canada in spring 2016 and fall 2016 to winter 2017) with songs recorded in a low latitude breeding ground (Dominican Republic in winter and spring 2017). High-quality song samples were selected, and every phrase annotated. Song theme order, song duration, and number of phrase repetitions were compared across samples. The most variability in theme order was found between November and December in the Canadian recordings, a phase in song ontogeny that may be important for learning. Song duration gradually increased, via an increase in phrase repetitions, through the breeding season, before peaking in the Dominican Republic between January and March. A comparison to oscine bird seasonal song ontogeny revealed many similarities, highlighting potentially similar physiological processes between humpback whales and songbirds.
{"title":"Seasonal song ontogeny in western North Atlantic humpback whales: drawing parallels with songbirds","authors":"Katie A. Kowarski, S. Cerchio, H. Whitehead, Danielle M. Cholewiak, H. Moors-Murphy","doi":"10.1080/09524622.2022.2122561","DOIUrl":"https://doi.org/10.1080/09524622.2022.2122561","url":null,"abstract":"ABSTRACT The use of song as a reproductive display is common in the animal kingdom; however, for many taxa, little is known of song ontogeny. Male humpback whales produce elaborate songs on low latitude breeding grounds in winter and begin to sing on high latitude feeding grounds in late summer, yet songs from the two locations are rarely compared. Seasonal song ontogeny in western North Atlantic humpback whales was explored by comparing songs recorded in high latitude feeding grounds (Canada in spring 2016 and fall 2016 to winter 2017) with songs recorded in a low latitude breeding ground (Dominican Republic in winter and spring 2017). High-quality song samples were selected, and every phrase annotated. Song theme order, song duration, and number of phrase repetitions were compared across samples. The most variability in theme order was found between November and December in the Canadian recordings, a phase in song ontogeny that may be important for learning. Song duration gradually increased, via an increase in phrase repetitions, through the breeding season, before peaking in the Dominican Republic between January and March. A comparison to oscine bird seasonal song ontogeny revealed many similarities, highlighting potentially similar physiological processes between humpback whales and songbirds.","PeriodicalId":55385,"journal":{"name":"Bioacoustics-The International Journal of Animal Sound and Its Recording","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41983623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-16DOI: 10.1080/09524622.2022.2106306
Jessica J. Sportelli, Brittany L. Jones, Sam H. Ridgway
ABSTRACT Biphonation, deterministic chaos, sidebands and subharmonics are four non-linear phenomena (NLP) that have been identified as common additions in the phonations of animals. NLP have been hypothesised to communicate urgency, caller identification, fitness and arousal/valence states for a variety of species but have yet to be studied in detail for bottlenose dolphins. For this study, the signature whistles of nine bottlenose dolphins residing at the US Navy Marine Mammal Program (MMP) were opportunistically recorded during routine periods of separation from conspecifics. NLP were found to be common additions onto the spectral structure of signature whistles, occurring in 53% of recorded whistles (340/642). Sidebands were the most common NLP type produced. Although less frequently emitted, biphonations were characterised by a significantly longer persistence than the other NLP types. Age had a negative correlation with overall NLP presence, and more specifically, sideband presence. Individual differences in NLP use existed between dolphins; however, all dolphins were recorded producing a minimum of two NLP types. We describe NLP prevalence in dolphin whistles in order to provide a useful baseline for continued research to further identify changes in NLP across behavioural and/or health conditions.
{"title":"Non-linear phenomena: a common acoustic feature of bottlenose dolphin (Tursiops truncatus) signature whistles","authors":"Jessica J. Sportelli, Brittany L. Jones, Sam H. Ridgway","doi":"10.1080/09524622.2022.2106306","DOIUrl":"https://doi.org/10.1080/09524622.2022.2106306","url":null,"abstract":"ABSTRACT Biphonation, deterministic chaos, sidebands and subharmonics are four non-linear phenomena (NLP) that have been identified as common additions in the phonations of animals. NLP have been hypothesised to communicate urgency, caller identification, fitness and arousal/valence states for a variety of species but have yet to be studied in detail for bottlenose dolphins. For this study, the signature whistles of nine bottlenose dolphins residing at the US Navy Marine Mammal Program (MMP) were opportunistically recorded during routine periods of separation from conspecifics. NLP were found to be common additions onto the spectral structure of signature whistles, occurring in 53% of recorded whistles (340/642). Sidebands were the most common NLP type produced. Although less frequently emitted, biphonations were characterised by a significantly longer persistence than the other NLP types. Age had a negative correlation with overall NLP presence, and more specifically, sideband presence. Individual differences in NLP use existed between dolphins; however, all dolphins were recorded producing a minimum of two NLP types. We describe NLP prevalence in dolphin whistles in order to provide a useful baseline for continued research to further identify changes in NLP across behavioural and/or health conditions.","PeriodicalId":55385,"journal":{"name":"Bioacoustics-The International Journal of Animal Sound and Its Recording","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47927249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-25DOI: 10.1080/09524622.2022.2112289
Aileen C. van der Mescht, Chanel Lewis, Runè van der Merwe, D. Codron
ABSTRACT Animals adopt circadian rhythms and diel calling patterns to ensure successful breeding, avoid predators, and reduce intra- and inter-species competition. We determine the diel calling behaviour of the bush cricket, Acanthoplus discoidalis, across different vegetation types in the southern Kalahari, and whether any variation in calling behaviour exists across the different regions of the landscape. We identify potential environmental drivers impacting its calling behaviour, as well as any impact temperature and wind may have on the species’ calling behaviour. Acanthoplus discoidalis was recorded singing in all vegetation types, calling starts around 10h00 and ceases at 00h00, with a peak from 15h00 to 23h00, a longer peak than expected based on previous studies. This pattern was consistent across all vegetation types, although calling intensity was less in mountainous, rocky, and windy areas. A likely explanation for the expanded diel pattern is that sampling occurred during a mass emergence of the species, and so a wider temporal niche could be a response to reduce intraspecies competition for females. Furthermore, this diel calling pattern may reduce encounters with predators, which are typically either strictly nocturnal or diurnal, yet it is likely this species relies on physical defences over acoustic adaptations to avoid predation.
{"title":"Hurry up and sing: early onset of diel calling behaviour and ecological drivers of calling behaviour of Acanthoplus discoidalis","authors":"Aileen C. van der Mescht, Chanel Lewis, Runè van der Merwe, D. Codron","doi":"10.1080/09524622.2022.2112289","DOIUrl":"https://doi.org/10.1080/09524622.2022.2112289","url":null,"abstract":"ABSTRACT Animals adopt circadian rhythms and diel calling patterns to ensure successful breeding, avoid predators, and reduce intra- and inter-species competition. We determine the diel calling behaviour of the bush cricket, Acanthoplus discoidalis, across different vegetation types in the southern Kalahari, and whether any variation in calling behaviour exists across the different regions of the landscape. We identify potential environmental drivers impacting its calling behaviour, as well as any impact temperature and wind may have on the species’ calling behaviour. Acanthoplus discoidalis was recorded singing in all vegetation types, calling starts around 10h00 and ceases at 00h00, with a peak from 15h00 to 23h00, a longer peak than expected based on previous studies. This pattern was consistent across all vegetation types, although calling intensity was less in mountainous, rocky, and windy areas. A likely explanation for the expanded diel pattern is that sampling occurred during a mass emergence of the species, and so a wider temporal niche could be a response to reduce intraspecies competition for females. Furthermore, this diel calling pattern may reduce encounters with predators, which are typically either strictly nocturnal or diurnal, yet it is likely this species relies on physical defences over acoustic adaptations to avoid predation.","PeriodicalId":55385,"journal":{"name":"Bioacoustics-The International Journal of Animal Sound and Its Recording","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47840978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-18DOI: 10.1080/09524622.2022.2108145
F. Shabangu, G. Hofmeyr, R. Probert, M. Connan, Corrine A. Buhrmann, T. Gridley
ABSTRACT In-air sounds of pinnipeds are important for interactions with conspecifics and threat displays. However, little is known about the in-air acoustic repertoire and associated behaviour of crabeater seals Lobodon carcinophaga. We investigated the in-air acoustic repertoire and associated behaviour of two male and one female wild juvenile crabeater seals that beached separately, and were rehabilitated in Durban and Gqeberha, South Africa. In-air sounds were visually identified and categorised into five classes validated via random forest model classification: brief, intermediate, and long moan calls, croaks, and hisses. Hisses were common (n = 25,105 sounds from 136 hrs of acoustic recordings) and detected during heightened arousal states and interactions with animal care staff and a conspecific. Furthermore, hisses were also recorded in low arousal states during exhalation. Moan calls (n = 241) were only detected from two of the three seals. During rehabilitation, the female seal ceased producing moan calls and later produced a series of croaks (n = 204). Acoustic characteristics of in-air moan calls differed from published underwater moan calls according to duration, minimum, and maximum frequencies, and pulse repetition rate. Our study shows that the in-air acoustic repertoire and associated behaviour of these Antarctic seals are dynamic, vary inter-individually and are context dependent.
{"title":"In-air acoustic repertoire and associated behaviour of wild juvenile crabeater seals during rehabilitation","authors":"F. Shabangu, G. Hofmeyr, R. Probert, M. Connan, Corrine A. Buhrmann, T. Gridley","doi":"10.1080/09524622.2022.2108145","DOIUrl":"https://doi.org/10.1080/09524622.2022.2108145","url":null,"abstract":"ABSTRACT In-air sounds of pinnipeds are important for interactions with conspecifics and threat displays. However, little is known about the in-air acoustic repertoire and associated behaviour of crabeater seals Lobodon carcinophaga. We investigated the in-air acoustic repertoire and associated behaviour of two male and one female wild juvenile crabeater seals that beached separately, and were rehabilitated in Durban and Gqeberha, South Africa. In-air sounds were visually identified and categorised into five classes validated via random forest model classification: brief, intermediate, and long moan calls, croaks, and hisses. Hisses were common (n = 25,105 sounds from 136 hrs of acoustic recordings) and detected during heightened arousal states and interactions with animal care staff and a conspecific. Furthermore, hisses were also recorded in low arousal states during exhalation. Moan calls (n = 241) were only detected from two of the three seals. During rehabilitation, the female seal ceased producing moan calls and later produced a series of croaks (n = 204). Acoustic characteristics of in-air moan calls differed from published underwater moan calls according to duration, minimum, and maximum frequencies, and pulse repetition rate. Our study shows that the in-air acoustic repertoire and associated behaviour of these Antarctic seals are dynamic, vary inter-individually and are context dependent.","PeriodicalId":55385,"journal":{"name":"Bioacoustics-The International Journal of Animal Sound and Its Recording","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41591780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-10DOI: 10.1080/09524622.2022.2105954
G. Frydman, Yael Goll, E. Geffen, L. Koren
ABSTRACT Sex differences in vocalizations are found across the animal kingdom, which may be due to different vocal apparatus, call function, and context. Rock hyraxes (Procavia capensis) of both sexes are vocal, but the sexes differ in repertoire size, call usage, and amplitude. In this study we examined sex differences in vocalization frequencies and predicted that they will be low and that frequency ranges will overlap since sexual size dimorphism in this species is modest (~ 15%). We utilized two datasets: recordings of captive hyraxes using a condenser microphone; and audio files of wild-living individuals recorded via a miniature recorder mounted on a collar. With the exclusion of two proximate call types recorded in the wild, all calls featured an ultrasonic component. However, in females there was an effect of duration on minimal frequency. Warning trills, which are heard by humans far away, featured the highest maximal visible harmonic in both datasets. No relationship was found between calling distance and the maximal harmonic in males, while in wild females, distant calls featured higher frequencies. Our results show sex differences in hyrax vocalization frequencies. Exploring the information encoded in frequencies beyond the human hearing range may expand our understanding of animal communication.
{"title":"Sex differences in frequencies in a species with modest sexual size dimorphism","authors":"G. Frydman, Yael Goll, E. Geffen, L. Koren","doi":"10.1080/09524622.2022.2105954","DOIUrl":"https://doi.org/10.1080/09524622.2022.2105954","url":null,"abstract":"ABSTRACT Sex differences in vocalizations are found across the animal kingdom, which may be due to different vocal apparatus, call function, and context. Rock hyraxes (Procavia capensis) of both sexes are vocal, but the sexes differ in repertoire size, call usage, and amplitude. In this study we examined sex differences in vocalization frequencies and predicted that they will be low and that frequency ranges will overlap since sexual size dimorphism in this species is modest (~ 15%). We utilized two datasets: recordings of captive hyraxes using a condenser microphone; and audio files of wild-living individuals recorded via a miniature recorder mounted on a collar. With the exclusion of two proximate call types recorded in the wild, all calls featured an ultrasonic component. However, in females there was an effect of duration on minimal frequency. Warning trills, which are heard by humans far away, featured the highest maximal visible harmonic in both datasets. No relationship was found between calling distance and the maximal harmonic in males, while in wild females, distant calls featured higher frequencies. Our results show sex differences in hyrax vocalization frequencies. Exploring the information encoded in frequencies beyond the human hearing range may expand our understanding of animal communication.","PeriodicalId":55385,"journal":{"name":"Bioacoustics-The International Journal of Animal Sound and Its Recording","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2022-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48152903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-14DOI: 10.1080/09524622.2022.2086174
I. P. Maiditsch, F. Ladich
ABSTRACT Numerous fishes produce sounds and their transmission and detection may be hindered by increasing levels of anthropogenic noise. We investigated acoustic communication during dyadic contests between male croaking gouramis (Trichopsis vittata, Osphronemidae) in the presence and absence of white noise. We hypothesised that fish modify acoustic signalling in the presence of noise in order to maintain intraspecific communication. Under controlled laboratory settings we compared agonistic behaviour, visual and acoustic signalling between noise and no-noise conditions. Trichopsis vittata produced sounds that were significantly lower in level and higher in dominant frequency under noise treatments. No difference was found in visual signalling or temporal sound characteristics. This study indicates that noise does not affect the amount of signalling during agonistic behaviour in a highly vocal fish. No increase in sound level was observed in croaking gouramis, indicating that a Lombard effect is not present in all vocalising fish. The lack of a Lombard effect shows that sound communication is potentially hindered by (human-made) noise in fish, which may affect territory maintenance and reproduction.
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