Transmission beam pattern and dynamics of a spinner dolphin (<i>Stenella longirostris</i>)

Smith, Anthony; Pacini, Aude F.; Nachtigall, Paul E.; Laule, Gail; Aragones, Lemnuel V.; Magno, Carlo; Suarez, Leo

doi:10.1121/1.5111347

Cited by 5 publications

(3 citation statements)

References 38 publications

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“…the sensor [38]. Clicks which arrive at a sensor from an off-axis path are typically distorted relative to their on-axis counterparts, with complex waveforms, amplitude and peak frequency decreasing as a function of off-axis angle, and spectral notches often being introduced [7,52,[57][58][59]. Angle of off-axis is also an important consideration, as click which are only slightly off-axis may appear very similar to on-axis clicks.…”

Section: Plos Onementioning

confidence: 99%

Identification of western North Atlantic odontocete echolocation click types using machine learning and spatiotemporal correlates

et al. 2022

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A combination of machine learning and expert analyst review was used to detect odontocete echolocation clicks, identify dominant click types, and classify clicks in 32 years of acoustic data collected at 11 autonomous monitoring sites in the western North Atlantic between 2016 and 2019. Previously-described click types for eight known odontocete species or genera were identified in this data set: Blainville’s beaked whales (Mesoplodon densirostris), Cuvier’s beaked whales (Ziphius cavirostris), Gervais’ beaked whales (Mesoplodon europaeus), Sowerby’s beaked whales (Mesoplodon bidens), and True’s beaked whales (Mesoplodon mirus), Kogia spp., Risso’s dolphin (Grampus griseus), and sperm whales (Physeter macrocephalus). Six novel delphinid echolocation click types were identified and named according to their median peak frequencies. Consideration of the spatiotemporal distribution of these unidentified click types, and comparison to historical sighting data, enabled assignment of the probable species identity to three of the six types, and group identity to a fourth type. UD36, UD26, and UD28 were attributed to Risso’s dolphin (G. griseus), short-finned pilot whale (G. macrorhynchus), and short-beaked common dolphin (D. delphis), respectively, based on similar regional distributions and seasonal presence patterns. UD19 was attributed to one or more species in the subfamily Globicephalinae based on spectral content and signal timing. UD47 and UD38 represent distinct types for which no clear spatiotemporal match was apparent. This approach leveraged the power of big acoustic and big visual data to add to the catalog of known species-specific acoustic signals and yield new inferences about odontocete spatiotemporal distribution patterns. The tools and call types described here can be used for efficient analysis of other existing and future passive acoustic data sets from this region.

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Section: Plos Onementioning

confidence: 99%

Identification of western North Atlantic odontocete echolocation click types using machine learning and spatiotemporal correlates

et al. 2022

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“… Inter-species comparison of 3-dB beamwidths and directivity indices, based on the ratio of head diameter

to the wavelength

of the click peak frequency. The data include in situ measurements from the false killer whale [ 35 ], Risso’s dolphin [ 4 ], harbor porpoise [ 31 , 36 ], bottlenose dolphin [ 37 ], beluga whale ( Delphinapterus leucas ) [ 38 ], and spinner dolphin ( Stenella longirostris ) [ 39 ], as well as FEA results from the Yangtze finless porpoise [ 19 ], baiji [ 15 ], bottlenose dolphin [ 13 ], and harbor porpoise [ 14 ]. …”

Section: Figurementioning

confidence: 99%

The Distinctive Forehead Cleft of the Risso’s Dolphin (Grampus griseus) Hardly Affects Biosonar Beam Formation

Wei

Gill

Erbe

et al. 2022

Animals

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The Risso’s dolphin (Grampus griseus) has a distinctive vertical crease (or cleft) along the anterior surface of the forehead. Previous studies have speculated that the cleft may contribute to biosonar beam formation. To explore this, we constructed 2D finite element models based on computer tomography data of the head of a naturally deceased Risso’s dolphin. The simulated acoustic near-field signals, far-field signals, and transmission beam patterns were compared to corresponding measurements from a live, echolocating Risso’s dolphin. To investigate the effect of the cleft, we filled the cleft with neighboring soft tissues in our model, creating a hypothetical “cleftless” forehead, as found in other odontocetes. We compared the acoustic pressure field and the beam pattern between the clefted and cleftless cases. Our results suggest that the cleft plays an insignificant role in forehead biosonar sound propagation and far-field beam formation. Furthermore, the cleft was not responsible for the bimodal click spectrum recorded and reported from this species.

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“…A subpopulation of Irrawaddy dolphin, on the other hand, appears to have an exceedingly small, restricted core habitat in Guimaras Strait (de la Paz et al, 2020). Three studies explored bioacoustics with one experimenting on a captive spinner dolphin (Smith et al, 2019) and the other two on humpback whale songs. Songs recorded in the Babuyan Islands were compared to songs from other stocks across the North Pacific revealing interesting patterns of convergence and divergence (Darling et al, 2014(Darling et al, , 2019.…”

Section: Biology and Ecologymentioning

confidence: 99%

Patterns of Research Effort and Extinction Risk of Marine Mammals in the Philippines

2021

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Global marine mammal research is disproportionately lacking compared to terrestrial mammal research and is strongly biased toward populations in Europe, North America, New Zealand, and Australia. With high extinction risks facing marine mammals in the tropics, we sought to identify potential drivers of research effort and extinction risk evaluations for marine mammals in the Philippines as a model for tropical island nations with limited resources and research capacity. Using a bibliographic approach, we compiled all materials on marine mammal research in the Philippines from 1991 to 2020, which we categorized into eight thematic areas of research focus. We reviewed all materials based on their research focus to assess the current scientific knowledge of local marine mammal populations. Using a simple metric to calculate research effort allocation, we found that all marine mammal species in the Philippines receive inadequate research attention. Using generalized linear models, we analyzed the relationship of potential factors that drive research effort. The model with the lowest Akaike Information Criterion value suggests that frequency of marine mammal stranding incidents may influence an increase in research effort on marine mammals by providing access to biological specimens that would normally be difficult to obtain. Strandings are unfortunate events with often unclear causes, but they provide an opportunity to collect data from behaviorally cryptic animals in areas where financial constraints often hamper scientific progress. We also determined that a national Red List evaluation was predicted by increased research effort. Maximizing local research using all materials from strandings and building research capacity may be an alternative to expensive field-based methods to increase knowledge on local marine mammal populations.

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Transmission beam pattern and dynamics of a spinner dolphin (Stenella longirostris)

Abstract: Click characteristics of northern bottlenose whales (Hyperoodon ampullatus) and Sowerby's beaked whales (Mesoplodon bidens) off eastern Canada

Cited by 5 publications

References 38 publications

Identification of western North Atlantic odontocete echolocation click types using machine learning and spatiotemporal correlates

Identification of western North Atlantic odontocete echolocation click types using machine learning and spatiotemporal correlates

The Distinctive Forehead Cleft of the Risso’s Dolphin (Grampus griseus) Hardly Affects Biosonar Beam Formation

Patterns of Research Effort and Extinction Risk of Marine Mammals in the Philippines

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