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  • Directionality  (2)
  • Animal communication  (1)
  • 1
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © The Company of Biologists, 2015. This article is posted here by permission of The Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology 218 (2015): 3091-3101, doi:10.1242/jeb.120501.
    Beschreibung: Toothed whales produce echolocation clicks with source parameters related to body size; however, it may be equally important to consider the influence of habitat, as suggested by studies on echolocating bats. A few toothed whale species have fully adapted to river systems, where sonar operation is likely to result in higher clutter and reverberation levels than those experienced by most toothed whales at sea because of the shallow water and dense vegetation. To test the hypothesis that habitat shapes the evolution of toothed whale biosonar parameters by promoting simpler auditory scenes to interpret in acoustically complex habitats, echolocation clicks of wild Amazon river dolphins were recorded using a vertical seven-hydrophone array. We identified 404 on-axis biosonar clicks having a mean SLpp of 190.3±6.1 dB re. 1 µPa, mean SLEFD of 132.1±6.0 dB re. 1 µPa2s, mean Fc of 101.2±10.5 kHz, mean BWRMS of 29.3±4.3 kHz and mean ICI of 35.1±17.9 ms. Piston fit modelling resulted in an estimated half-power beamwidth of 10.2 deg (95% CI: 9.6–10.5 deg) and directivity index of 25.2 dB (95% CI: 24.9–25.7 dB). These results support the hypothesis that river-dwelling toothed whales operate their biosonars at lower amplitude and higher sampling rates than similar-sized marine species without sacrificing high directivity, in order to provide high update rates in acoustically complex habitats and simplify auditory scenes through reduced clutter and reverberation levels. We conclude that habitat, along with body size, is an important evolutionary driver of source parameters in toothed whale biosonars.
    Beschreibung: Field work was funded by Danish National Research Council grants to P.T.M., Associação Amigos do Peixe Boi da Amazônia (AMPA) and Petrobras Ambiental grants to V.M.F.d.S., Augustinus Fonden grants to M.L. and a travelling fellowship awarded to M.d.F. by Journal of Experimental Biology. M.L. was funded by a PhD stipend from the Faculty of Science and Technology, Aarhus University, and National Research Council grants to P.T.M. F.H.J. was funded by a Carlsberg Foundation travel grant.
    Beschreibung: 2016-10-07
    Schlagwort(e): Beamwidth ; Clutter ; Directionality ; Echolocation ; Habitat ; Toothed whale
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2022-05-26
    Beschreibung: Author Posting. © The Company of Biologists, 2015. This is the author's version of the work. It is posted here by permission of Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology (2015), doi:10.1242/​jeb.116285.
    Beschreibung: Echolocating animals exercise an extensive control over the spectral and temporal properties of their biosonar signals to facilitate perception of their actively generated auditory scene when homing in on prey. The intensity and directionality of the biosonar beam defines the field of view of echolocating animals by affecting the acoustic detection range and angular coverage. However, the spatial relationship between an echolocating predator and its prey changes rapidly, resulting in different biosonar requirements throughout prey pursuit and capture. Here we measured single click beam patterns using a parametric fit procedure to test whether free-ranging Atlantic spotted dolphins (Stenella frontalis) modify their biosonar beamwidth. We recorded echolocation clicks using a linear array of receivers and estimated the beamwidth of individual clicks using a parametric spectral fit, cross-validated with well-established composite beam pattern estimates. The dolphins apparently increased the biosonar beamwidth, to a large degree without changing the signal frequency, when they approached the recording array. This is comparable to bats that also expand their field of view during prey capture, but achieve this by decreasing biosonar frequency. This behaviour may serve to decrease the risk that rapid escape movements of prey take them outside the biosonar beam of the predator. It is likely that shared sensory requirements have resulted in bats and toothed whales expanding their acoustic field of view at close range to increase the likelihood of successfully acquiring prey using echolocation, representing a case of convergent evolution of echolocation behaviour between these two taxa.
    Beschreibung: The study was funded by frame grants from the Danish Natural Science Foundation to PTM and MW, and by the National Oceanographic Partnership Programme via a research agreement between La Laguna University (NAS) and the Woods Hole Oceanographic Institution (MJ). FHJ was supported by the Danish Council for Independent Research | Natural Sciences, and is currently funded by a postdoctoral fellowship from the Carlsberg Foundation.
    Beschreibung: 2016-03-12
    Schlagwort(e): Echolocation ; Directionality ; Field of view ; Perception ; Dolphin ; Prey capture
    Repository-Name: Woods Hole Open Access Server
    Materialart: Preprint
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2022-11-07
    Beschreibung: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Lehmann, K. D. S., Jensen, F. H., Gersick, A. S., Strandburg-Peshkin, A., & Holekamp, K. E. Long-distance vocalizations of spotted hyenas contain individual, but not group, signatures. Proceedings of the Royal Society B: Biological Sciences, 289(1979), (2022): 20220548, https://doi.org/10.1098/rspb.2022.0548.
    Beschreibung: 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.
    Beschreibung: This work was supported by National Science Foundation grant nos OISE1853934 and IOS1755089, Carlsberg Foundation grant no. CF 15-0915 and Human Frontier Science Program grant no. RGP0051/2019. K.D.S.L. was supported by a Graduate Research Fellowship from NSF. A.S.P. received additional funding from the Gips-Schüle Stiftung, the Max Planck Institute of Animal Behaviour, and the Zukunftskolleg at the University of Konstanz. F.H.J. was funded through an AIAS-COFUND fellowship from Aarhus Institute of Advanced Studies under the FP7-PEOPLE programme of the EU (agreement no. 609033).
    Schlagwort(e): Long-distance signals ; Animal communication ; Group signatures ; Individual signatures
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Standort Signatur Erwartet Verfügbarkeit
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