[MARMAM] New publication!! Peale's dolphins (Lagenorhynchus australis) are acoustic mergers between dolphins and porpoises
Dear Colleagues, On behalf of my co-authors, I am excited to share our new publication in the Journal of Experimental Marine Biology and Ecology: *Morgan J. Martin, Sara Torres Ortiz, Magnus Wahlberg, and Caroline R. Weir. (2024). Peale's dolphins (Lagenorhynchus australis) are acoustic mergers between dolphins and porpoises. Journal of Experimental Marine Biology and Ecology, 572 (2024): 151977.* The published paper is open access and freely downloadable to anyone with this link: https://doi.org/10.1016/j.jembe.2023.151977 *Highlights:* • Peale's dolphins produce whistles & broadband clicks in addition to NBHF clicks. • Whistle & broadband signal co-occurrence indicates a likely communication function. • Whistles were similar for Peale's dolphins & four additional* Lagenorhynchus* species. • Demonstrates a lack of convergent whistle loss in this NBHF species at this time. *Abstract:* Most dolphin species produce broadband clicks for echolocation (i.e., biosonar pulses), and whistles and burst-pulsed calls for communication purposes. A few dolphin species in the southern hemisphere are reported to only produce clicks of a more narrowband high-frequency (NBHF) type, very similar to the clicks produced by porpoises. Here, we use underwater acoustic recordings of Peale's dolphins (*Lagenorhynchus australis*) in the Falkland Islands to show that they also can produce broadband clicks and tonal whistle sounds similar to other whistling odontocete species in addition to NBHF clicks. Whistles and broadband clicks co-occurred in seven out of twelve acoustic encounters with Peale's dolphins. The co-occurrence of whistles and broadband signals, which were predominately burst-pulses, produced by Peale's dolphins in this study points to a probable function as communication signals. Furthermore, the measured frequency and time parameters of Peale's dolphin whistles were comparable with whistles recorded from four additional species in the *Lagenorhynchus* genus in various parts of their ranges. This is the only species of *Lagenorhynchus* recorded to date that can relax acoustic crypsis in a similar manner as Heaviside's (*Cephalorhynchus heavisidii*), Commerson's (*C. commersonii*), and Hector's (*C. hectori*) dolphins. Our findings make it likely that additional NBHF species have the ability to generate both pulsed signal types and whistles, and further challenges the acoustic classification of NBHF species. For the audiophiles, we've included two supplementary .wav files which are ~ 30 seconds in duration and contain examples of Peale's dolphin NBHF clicks, broadband clicks, and whistles recorded during a socializing encounter from this study. They are downloadable files located at the very end of the discussion section in the web version of the paper. Please feel free to email me for a PDF copy at mjmar...@sandiego.edu. Cheers, Morgan J. Martin, PhD *Marine Bioacoustician* *Center for Marine Acoustics* *Bureau of Ocean Energy Management (USA)* ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication: Hector’s dolphins (Cephalorhynchus hectori) produce both narrowband high-frequency and broadband acoustic signals
Dear Colleagues, On behalf of my co-authors, I am very excited to share our new publication in JASA: *Nicoline Abildtrup Nielsen, Stephen M. Dawson, Sara Torres Ortiz, Magnus Wahlberg, and Morgan J. Martin (2024). Hector’s dolphins (Cephalorhynchus hectori) produce both narrowband high-frequency and broadband acoustic signals. The Journal of the Acoustical Society of America, 155(2), 1437–1450. https://doi.org/10.1121/10.0024820 <https://doi.org/10.1121/10.0024820>* The paper is available here: https://pubs.aip.org/asa/jasa/article-abstract/155/2/1437/3265783/Hector-s-dolphins-Cephalorhynchus-hectori-produce?redirectedFrom=fulltext Abstract: Odontocetes produce clicks for echolocation and communication. Most odontocetes are thought to produce either broadband (BB) or narrowband high-frequency (NBHF) clicks. Here, we show that the click repertoire of Hector's dolphin (*Cephalorhynchus hectori*) comprises highly stereotypical NBHF clicks and far more variable broadband clicks, with some that are intermediate between these two categories. Both NBHF and broadband clicks were made in trains, buzzes, and burst-pulses. Most clicks within click trains were typical NBHF clicks, which had a median centroid frequency of 130.3 kHz (median –10 dB bandwidth = 29.8 kHz). Some, however, while having only marginally lower centroid frequency (median = 123.8 kHz), had significant energy below 100 kHz and approximately double the bandwidth (median –10 dB bandwidth = 69.8 kHz); we refer to these as broadband. Broadband clicks in buzzes and burst-pulses had lower median centroid frequencies (120.7 and 121.8 kHz, respectively) compared to NBHF buzzes and burst-pulses (129.5 and 130.3 kHz, respectively). Source levels of NBHF clicks, estimated by using a drone to measure ranges from a single hydrophone and by computing time-of-arrival differences at a vertical hydrophone array, ranged from 116 to 171 dB re 1 μPa at 1 m, whereas source levels of broadband clicks, obtained from array data only, ranged from 138 to 184 dB re 1 μPa at 1 m. Our findings challenge the grouping of toothed whales as either NBHF or broadband species. Please feel free to email me for a PDF copy at mjmar...@sandiego.edu or morgan.mar...@boem.gov Cheers, Morgan J. Martin, PhD *Bioacoustician* *Center for Marine Acoustics* *Bureau of Ocean Energy Management (USA)* ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication: Exposure and behavioural responses of tagged bowhead whales (Balaena mysticetus) to vessels in the Pacific Arctic
Greetings! On behalf of my coauthors, I am happy to share the link to an open-access paper we published today in* Arctic Science*: Martin, M.J., Halliday, W.D., Citta, J.J., Quakenbush, L., Harwood, L., Lea, E.V., Dawson, J., Nicoll, A., Insley, S.J. (2023) Exposure and behavioural responses of tagged bowhead whales (*Balaena mysticetus*) to vessels in the Pacific Arctic. *Arctic Scienc*e. e-First: https://doi.org/10.1139/as-2022-0052 Link to the freely downloadable paper: https://doi.org/10.1139/AS-2022-0052 *Abstract:* Arctic marine mammals face many challenges linked to climate change, including increasing anthropogenic noise from vessel traffic. The bowhead whale (*Balaena mysticetus* Linnaeus, 1758), an Arctic endemic cetacean, relies on acoustic communication, with documented overlapping frequencies between communication and vessel noise. Bering–Chukchi–Beaufort (BCB) bowhead whales migrate through areas with the highest levels of vessel traffic in the Pacific Arctic. Here, we document the spatial and temporal overlap between 25 satellite-tagged BCB bowhead whales and vessels during July–December, 2012–2018. We report 1332 occasions when a vessel was within 125 km of a tagged whale, and where possible, quantified changes in swim speed to investigate individual behavioural responses to vessel approaches within a 50 km radius (n = 18 encounters). In the quantitative analysis, bowhead whales were not observed to alter swim speed within 8–50 km of vessels (we could not assess distances <8 km). Our results suggest that bowhead whales did not exhibit detectable long-range (i.e., up to 50 km) behavioural responses to vessels, consistent with observations of closely related North Atlantic right whales (*Eubalaena glacialis* (Muller, 1776)), for which vessel strikes are a leading cause of mortality. More work is required to assess how bowhead whales react to vessels at closer distances. Please check out this website for a list of additional publications on our research on marine mammals and noise in the Arctic: http://www.arcticnoise.ca/publications.html Please feel free to email me for a pdf copy of our new paper if you have issues accessing the link. mjmar...@sandiego.edu Cheers, Morgan J. Martin, PhD Wildlife Conservation Society Canada University of Victoria, B.C., Canada ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication: Exposure and behavioral responses of tagged beluga whales (Delphinapterus leucas) to ships in the Pacific Arctic
Dear All, We are excited to inform you that a new paper has been published on the behavioral responses of tagged beluga whales to ships and ship noise in the Pacific Arctic. This paper describes the surface movements and dive behavior of nine tagged Eastern Beaufort Sea belugas during encounters with vessels off Canada, Alaska and Russia. The paper is open access and freely available online via the following link. Please consider downloading the supplementary materials file which contains animations and dive profiles of each beluga encounter with one or more vessels. Martin, M. J., Halliday, W. D., Storrie, L., Citta, J. J., Dawson, J., Hussey, N. E., Juanes, F., Loseto, L. L., MacPhee, S. A., Moore, L., Nicoll, A., O'Corry-Crowe, G., & Insley, S. J. (2022). Exposure and behavioral responses of tagged beluga whales (*Delphinapterus leucas*) to ships in the Pacific Arctic. Marine Mammal Science, 1–35. https://doi.org/10./mms.12978 Supplementary animations and figures can be downloaded via this link: https://onlinelibrary.wiley.com/action/downloadSupplement?doi=10.%2Fmms.12978=mms12978-sup-0001-Figures_and_Animations.ppsx Abstract: Arctic marine mammals face a multitude of challenges linked to climate change, including increasing anthropogenic noise from ship traffic. The beluga whale (*Delphinapterus leucas*), a predominately Arctic endemic cetacean, relies heavily on acoustic communication, with documented overlap between their vocalizations and hearing range and ship noise. Some belugas migrate through areas with the highest levels of ship traffic in the Pacific Arctic and exposure to ship noise is highly probable. Here, we document the responses of nine satellite-tagged Eastern Beaufort Sea belugas to encounters with ships in the Beaufort, Chukchi, and Bering Seas during July–December 2018. We report 177 occasions when ships were within 125 km of tagged belugas and quantified changes in lateral and vertical movements to investigate individual behavioral responses to ship approaches within 50 km (n = 23). Belugas' swim speed was negatively correlated with ship distance, showing possible changes in swim speed up to 79 km away. Changes in lateral and vertical movements, indicating disruption of behavior, were observed when some ships passed within 50 km. These findings corroborate previous studies that have shown behavioral responses of belugas to ships at distances far beyond visual range, implying belugas react to low-amplitude ship noise near ambient levels. PDF requests can be sent to mjmar...@sandiego.edu Thank you for your time! Morgan J. Martin, PhD Postdoctoral researcher Wildlife Conservation Society Canada University of Victoria, Canada ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication: Commerson's dolphins can relax acoustic crypsis
Dear All, On behalf of my co-authors, I am pleased to announce the publication of our new paper, "Commerson’s dolphins (*Cephalorhynchus commersonii*) can relax acoustic crypsis". Morgan J. Martin, Sara Torres Ortiz, M. Vanesa Reyes Reyes, Alexander Marino, Miguel Iñíguez Bessega, & Magnus Wahlberg (2021). Commerson’s dolphins (*Cephalorhynchus commersonii*) can relax acoustic crypsis. *Behavioral Ecology and Sociobiology*, 75(6), 100. doi:10.1007/s00265-021-03035-y Abstract: Toothed whales use powerful ultrasonic biosonar pulses (i.e. clicks) for echolocation. Underwater acoustic recordings have suggested that the majority of toothed whale species can be grouped acoustically as either producing broadband clicks or narrowband high-frequency (NBHF) clicks. Recently, it has been shown that Heaviside’s dolphins, *Cephalorhynchus heavisidii*, emit NBHF clicks for echolocation but also clicks of lower frequency and broader bandwidth for communication. Here, we use acoustic recorders and drone video footage to reinforce previous findings that Commerson’s dolphins (*C. commersonii*) produce signals similar to Heaviside’s dolphins. We reveal that they use clicks with a lower frequency and broader bandwidth in the form of click trains and burst-pulses. These sounds were not recorded in the presence of smaller groups of Commerson’s dolphins, indicating that they may fulfil a communication function in larger groups. Also, we utilised a novel combination of drone video footage paired with underwater acoustic recordings to estimate the source level of echolocation clicks produced by Commerson’s dolphins. In addition, we compare the acoustic signals produced by Commerson’s and Heaviside’s dolphins to identify interspecific similarities and differences. Spectral differences were found in NBHF click trains, buzzes and burst-pulses between species; however, bandwidth and duration parameters were not significantly different for broadband click trains. Our findings make it likely that all four species of the *Cephalorhynchus* genus have the ability to generate both signal types, and further challenges the evolutionary concept of NBHF signal production. Significance statement: This study confirms the presence of a dual echolocation click (i.e. biosonar) strategy in Commerson’s dolphins, making them the second species of their genus known to produce two types of biosonar. We provide an in-depth quantitative analysis of Commerson’s dolphin acoustic signal types, and include a comparison of signal types between Commerson’s dolphins and the other species known to produce two types of biosonar, the Heaviside’s dolphin. *In addition, this is the first study to combine drone footage with underwater acoustic recordings to measure the source level of toothed whale echolocation signals.* We use this novel technique to provide source levels measured from Commerson’s dolphin echolocation clicks which are comparable to published values for this species calculated using an expensive and complicated array of hydrophones. Thus, we provide a simpler and more cost effective way to study sounds produced by marine mammals. This paper can be downloaded from: https://rdcu.be/cmXkC Please feel free to email me for a pdf copy at mjmar...@sandiego.edu Best wishes, Morgan J. Martin, PhD Postdoctoral researcher University of Victoria, BC, Canada Wildlife Conservation Society Canada ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] Two new publications about using PAM in distance sampling and estimating abundance of Heaviside's and dusky dolphins
Dear MARMAM Community, My co-authors and I are very pleased to share with you two recently published papers in *Frontiers in Marine Science* and the *African Journal of Marine Science*. The first paper provides the first abundance estimates for Heaviside's and dusky dolphins off Namibia. The second paper is a methods paper describing how we used PAM from a towed hydrophone array in combination with visual observers on line transect ship surveys to increase the detectability of Heaviside's dolphins. *First Abundance Estimates of Heaviside’s (Cephalorhynchus heavisidii) and Dusky (Lagenorhynchus obscurus) Dolphins Off Namibia Using a Novel Visual and Acoustic Line Transect Survey* Morgan J. Martin, Tess Gridley, Jean-Paul Roux and Simon H. Elwen To link to this article: https://doi.org/10.3389/fmars.2020.555659 *Abstract:* Knowledge of a population’s abundance is of primary importance for conservation management. However, robust estimates of abundance are often difficult to obtain, especially for cetaceans which spend most of their lives submerged. Cetacean abundance is commonly estimated using aerial or vessel-based line transect surveys and distance sampling methods. During 2012–2014, the first line transect surveys to estimate cetacean abundance were conducted in Namibian waters. Surveys took place in the Namibian Islands’ Marine Protected Area (NIMPA), a large MPA located along the southern Namibian coastline. A combined visual and acoustic double-platform survey configuration was used to investigate the factors affecting detectability of the endemic Heaviside’s dolphin (*Cephalorhynchus heavisidii*) and dusky dolphin (*Lagenorhynchus obscurus obscurus*). The present analysis estimates the probability of detection on the transect line (g(*0*)) for these two species and generates density and abundance estimates which incorporate a correction for both animals missed on the transect line and attractive responsive movement. The average annual baseline density and abundance estimates for Heaviside’s dolphins in the NIMPA region during 2012–2014 were 0.08 individuals/km2 (CV = 28.6%, 95% CI = 0.04–0.15 individuals/km2) and 1594 individuals (CV = 28.6%, 95% CI =776–3275), respectively. The average annual baseline density and abundance estimates for dusky dolphins in the NIMPA region during 2012–2014 were 0.16 individuals/km2 (CV = 26.2%, 95% CI = 0.10–0.28 individuals/km2) and 3493 individuals (CV = 26.2%, 95% CI: 2015–6052), respectively. A discussion on the distribution of Heaviside’s and dusky dolphins is provided for this region where such information is urgently needed. Based on existing knowledge of the species and area, these estimates are regarded as reasonable. They indicate moderate sized populations of animals within the NIMPA and provide an important first baseline on which future estimates can build. *Towed passive acoustic monitoring complements visual survey methods for Heaviside’s dolphins Cephalorhynchus heavisidii in the Namibian Islands Marine Protected Area* Tess Gridley , Morgan J. Martin , Jeffery Slater , J-P Roux , Rene J. Swift and Simon H. Elwen To link to this article: https://doi.org/10.2989/1814232X.2020.1848925 *Abstract:* The genus *Cephalorhynchus* contains four dolphin species, of which three are classified as Near Threatened or Endangered and one subspecies is close to extinction. Understanding the species’ abundance, distributions and habitat preferences is necessary for effective management to prevent further population declines. Heaviside’s dolphin* C. heavisidii* is endemic to the Benguela ecosystem off southwest Africa, and like other *Cephalorhynchus* species these dolphins produce narrowband high-frequency (NBHF) echolocation clicks with a centroid frequency around 125 kHz. We conducted dedicated visual and acoustic line-transect surveys within and adjacent to the Namibian Islands Marine Protected Area in 2012–2014. Acoustic data were processed in the passive acoustic monitoring software PAMGuard, using the default porpoise click detector and classifier to identify NBHF echolocation clicks. Click detection and classification in PAMGuard included a large excess of false positives, which were easily identified by manual verification of events, and ultimately provided 52 definite detections. The acoustic methods provided data in offshore areas and during overnight periods, but were imperfect and not suitable for ecologically important shallow coastal areas. While demonstrating the utility of passive acoustic monitoring in line-transect surveys targeting *Cephalorhynchus* species, the study shows that both visual and acoustic methods were needed to collect data throughout the range of Heaviside’s dolphin. Please feel free to email me for a pdf copy of either paper. Thank you for your interest in our research! Merry Christmas, Morgan J. Martin, PhD Postdoctoral researcher University of Victoria, B.C. ___ MARMAM mailing list
[MARMAM] New publication: The functional role of Heaviside's dolphin (Cephalorhynchus heavisidii) rapidly pulsed signals
Dear MARMAM Members, My co-authors and I are very pleased to announce the publication of our new manuscript "To buzz or burst-pulse? The functional role of Heaviside's dolphin, *Cephalorhynchus heavisidii,* rapidly pulsed signals" published in the Journal of Animal Behaviour. This study is the first to examine relationships between the surface and acoustic behaviours of Heaviside's dolphins. The reference and abstract are provided below. The article is available online now and will appear in the April issue of Animal Behaviour. Martin, M.J., Elwen, S.H., Kassanjee, R., Gridley, T. (2019). To buzz or burst-pulse? The functional role of Heaviside's dolphin, *Cephalorhynchus heavisidii,* rapidly pulsed signals. *Animal Behaviour*. DOI: 10.1016/j.anbehav.2019.01.007 Abstract: Four groups of toothed whales have independently evolved to produce narrowband high-frequency (NBHF) echolocation signals (i.e. clicks) with a strikingly similar waveform and centroid frequency around 125 kHz. These signals are thought to help NBHF species avoid predation by echolocating and communicating at frequencies inaudible to predators, a form of acoustic crypsis. Heaviside's dolphins produce NBHF echolocation clicks in trains and often in rapid succession in the form of buzzes. In addition, a second click type with a lower frequency and broader bandwidth was recently described, typically emitted in rapid succession in the form of burst-pulses. We investigated the relationship between buzz and burst-pulse signals and both surface behaviour (foraging, ‘interacting with the kayak’ and socializing) and group size, using a multivariable regression on the signal occurrence and signal count data. Signal occurrence and counts were not related to group size in the regression analysis. Burst-pulses were strongly linked to socializing behaviour, occurring more often and more frequently during socializing and much less during foraging. Buzz vocalizations were not strongly linked to a specific behaviour although there was some evidence of an increase in production during foraging and socializing. In addition, individual level production rates of buzzes during foraging and socializing, and burst-pulses during socializing decreased with increasing group size. Temporally patterned burst-pulse signals were also identified, often occurring within a series of burst-pulses and were directly linked to specific events such as aerial leaping, backflipping, tail slapping and potential mating. Our findings suggest Heaviside's dolphins have a more complex communication system based on pulsed vocalizations than previously understood, perhaps driven by the need to facilitate the social interactions of this species. The paper is available online at: https://doi.org/10.1016/j.anbehav.2019.01.007 A PDF is also available upon email request to: mjmar...@sandiego.edu Many thanks, Morgan Martin on behalf of my co-authors ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New publication: Heaviside's dolphins (Cephalorhynchus heavisidii) relax acoustic crypsis to increase communication range
Dear Colleagues, We are pleased to announce our recent publication on Heaviside's dolphin acoustic signals in the Proceedings of the Royal Society B: * Martin MJ, Gridley T, Elwen SH, Jensen FH. (2018) Heaviside’s dolphins (Cephalorhynchus heavisidii) relax acoustic crypsis to increase communication range. Proc. R. Soc. B 285: 20181178. http://dx.doi.org/10.1098/rspb.2018.1178 <http://dx.doi.org/10.1098/rspb.2018.1178> * Abstract: The costs of predation may exert significant pressure on the mode of communication used by an animal, and many species balance the benefits of communication (e.g. mate attraction) against the potential risk of predation. Four groups of toothed whales have independently evolved narrowband high-frequency (NBHF) echolocation signals. These signals help NBHF species avoid predation through acoustic crypsis by echolocating and communicating at frequencies inaudible to predators such as mammal-eating killer whales. Heaviside's dolphins (*Cephalorhynchus heavisidii*) are thought to exclusively produce NBHF echolocation clicks with a centroid frequency around 125 kHz and little to no energy below 100 kHz. To test this, we recorded wild Heaviside's dolphins in a sheltered bay in Namibia. We demonstrate that Heaviside's dolphins produce a second type of click with lower frequency and broader bandwidth in a frequency range that is audible to killer whales. These clicks are used in burst-pulses and occasional click series but not foraging buzzes. We evaluate three different hypotheses and conclude that the most likely benefit of these clicks is to decrease transmission directivity and increase conspecific communication range. The expected increase in active space depends on background noise but ranges from 2.5 (Wenz Sea State 6) to 5 times (Wenz Sea State 1) the active space of NBHF signals. This dual click strategy therefore allows these social dolphins to maintain acoustic crypsis during navigation and foraging, and to selectively relax their crypsis to facilitate communication with conspecifics. This paper can be accessed at: http://rspb.royalsocietypublishing.org/ content/285/1883/20181178.full Please contact me if you would like a PDF copy. Happy reading! Sincerely and on behalf of all authors, Morgan J. Martin ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
