Convergence of calls as animals form social bonds, active compensation for noisy communication channels, and the evolution of vocal learning in mammals

Author Posting. © American Psychological Association, 2008. This is the author's version of the work. It is posted here by permission of American Psychological Association for personal use, not for redistribution. The definitive version was published in Journal of Comparative Psychology 122 (2008): 319-331, doi:10.1037/a0013087.The classic evidence for vocal production learning involves imitation of novel, often anthropogenic sounds. Among mammals, this has been reported for African elephants, harbor seals, and dolphins. A broader taxonomic distribution has been reported for vocal convergence, where the acoustic properties of calls from different individuals converge when they are housed together in captivity or form social bonds in the wild. This kind of vocal convergence has been demonstrated for animals as diverse as songbirds, parakeets, bats, elephants, cetaceans, and primates. For most of these species, call convergence is thought to reflect a group-distinctive identifier, with shared calls reflecting and strengthening social bonds. Pooling data on vocal imitation and vocal convergence suggests a wider taxonomic distribution of vocal production learning among mammals than generally appreciated. The wide taxonomic distribution of this evidence for vocal production learning suggests that perhaps more of the neural underpinnings for vocal production learning are in place in mammals than is usually imagined. One ubiquitous function for vocal production learning that is starting to receive attention involves modifying signals to improve communication in a noisy channel

An optical telemetry device to identify which dolphin produces a sound

Author Posting. © Acoustical Society of America, 1985. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 78 (1985): 1892-1895, doi:10.1121/1.392777.A small telemetry device, called a "vocalight," was designed for attachment to a dolphin's head using a suction cup. The vocalight lights up a variable number of light-emitting diodes depending upon the loudness of sounds received at a hydrophone within the suction cup. If vocalights matched for sensitivity are put on each dolphin within a captive group, observers can identify which dolphin produces a vocalization. Use of vocalights indicates that source levels of whistles from captive bottlenosed dolphins, Tursiops truncatus, range from approximately 125 to over 140 dB re: 1 µPa at 1 m.This research was performed with financial assistance from a W.H.O.I. Postdoctoral Scholar Award and N.I.H. Postdoctoral Fellowship S-F32-NS07206

A datalogger to identify vocalizing dolphins

Author Posting. © Acoustical Society of America, 1991. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 90 (1991): 1668-1671, doi:10.1121/1.401908.A datalogger was developed to identify vocalizing dolphins within socially interacting captive groups. Every 50 ms the logger stores data on the level and frequency of detected sound. Dataloggers are temporarily attached to dolphins by suction cups for data collection sessions lasting up to 45 min. Later, computer analysis of data from the dataloggers reveals which dolphin produced each vocalization recorded during the session. Results from use of dataloggers with two captive bottlenose dolphins (Tursiops truncatus) at the New England Aquarium in Boston, MA are presented. The possible use of dataloggers with wild dolphins is discussed.This work was supported by ONR Grant No. N00014-87-K-0236

Postpartum whistle production in bottlenose dolphins

Author Posting. © Society for Marine Mammalogy, 2008. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Marine Mammal Science 24 (2008): 479-502, doi:10.1111/j.1748-7692.2008.00195.x.Despite much research on bottlenose dolphin signature whistles, few have investigated the role of maternal whistles in early calf development. We investigated maternal whistle use in the first weeks postpartum for captive dolphins. The overall whistling rate increased by a factor of ten when the calves were born and then decreased again in the third week of the one surviving calf. Adult whistles were distinguished from calf whistles based on the extent of frequency modulation and were further classified into signature and non-signature whistles by comparison to a dictionary of known whistles. The average rate of maternal signature whistle production increased significantly from 0.02 whistles per dolphin-minute before the calves were born to 0.2 and 0.3 whistles in weeks 1 and 2, decreasing again to 0.06 in week 3 for the mother of the surviving calf. Percent maternal signature whistles changed similarly. Signature whistle production by non-mothers did not change when the calves were born. A likely function of this increase in maternal signature whistle production is that it enables the calf to learn to identify the mother in the first weeks of life.This research was funded by a Howard Hughes Predoctoral Fellowship, the Ocean Ventures Fund, and the WHOI education department

Explorando el océano a través de paisajes sonoros

Listening to underwater soundscapes helps us understand how ocean physics and the biology of marine communities are responding to a dynamically changing ocean.Escuchar paisajes sonoros submarinos nos ayuda a entender cómo la física oceánica y la biología de las comunidades marinas están respondiendo a un océano que cambia dinámicamente

Experimental field studies to measure behavioral responses of cetaceans to sonar

Funding was provided by a variety of military and governmental funding sources from several nations acknowledged within referenced publications, notably the US Office of Naval Research, US Navy Living Marine Resources Program, and the navies of the USA, Norway, and the Netherlands. P.L.T. acknowledges the support of the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland) in the completion of this study. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions.Substantial recent progress has been made in directly measuring behavioral responses of free-ranging marine mammals to sound using controlled exposure experiments. Many studies were motivated by concerns about observed and potential negative effects of military sonar, including stranding events. Well-established experimental methods and increasingly sophisticated technologies have enabled fine-resolution measurement of many aspects of baseline behavior and responses to sonar. Studies have considered increasingly diverse taxa, but primarily odontocete and mysticete cetaceans that are endangered, particularly sensitive, or frequently exposed to sonar. This review focuses on recent field experiments studying cetacean responses to simulated or actual active military sonars in the 1 to 8 kHz band. Overall results demonstrate that some individuals of different species display clear yet varied responses, some of which have negative implications, while others appear to tolerate relatively high levels, although such exposures may have other consequences not measured. Responses were highly variable and may not be fully predictable with simple acoustic exposure metrics (e.g. received sound level). Rather, differences among species and individuals along with contextual aspects of exposure (e.g. behavioral state) appear to affect response probability. These controlled experiments provide critically needed documentation of identified behavioral responses occurring upon known sonar exposures, and they directly inform regulatory assessments of potential effects. They also inform more targeted opportunistic monitoring of potential responses of animals during sonar operations and have stimulated adaptations of field methods to consider increasingly realistic exposure scenarios and how contextual factors such as behavioral state and source proximity influence response type and probability.Publisher PDFPeer reviewe

Beaked whales echolocate on prey

Author Posting. © Royal Society, 2004. This article is posted here by permission of Royal Society for personal use, not for redistribution. The definitive version was published in Biology Letters 271: Supplement 6 (2004): S383-S386, doi:10.1098/rsbl.2004.0208.Beaked whales (Cetacea: Ziphiidea) of the genera Ziphius and Mesoplodon are so difficult to study that they are mostly known from strandings. How these elusive toothed whales use and react to sound is of concern because they mass strand during naval sonar exercises. A new non-invasive acoustic recording tag was attached to four beaked whales (two Mesoplodon densirostris and two Ziphius cavirostris) and recorded high-frequency clicks during deep dives. The tagged whales only clicked at depths below 200 m, down to a maximum depth of 1267 m. Both species produced a large number of short, directional, ultrasonic clicks with no significant energy below 20 kHz. The tags recorded echoes from prey items; to our knowledge, a first for any animal echolocating in the wild. As far as we are aware, these echoes provide the first direct evidence on how free-ranging toothed whales use echolocation in foraging. The strength of these echoes suggests that the source level of Mesoplodon clicks is in the range of 200-220 dB re 1 μPa at 1 m. This paper presents conclusive data on the normal vocalizations of these beaked whale species, which may enable acoustic monitoring to mitigate exposure to sounds intense enough to harm them.Tag development was funded by a Cecil H. and Ida M. Green Award and the US Office of Naval Research. Fieldwork was funded by the Strategic Environmental Research and Development Program (SERDP) under program CS-1188, the Packard Foundation, and the Council of Environment of the Canary Islands, and was supported by University of La Laguna, BluWest, SACLANT Undersea Research Centre, and the Government of El Hierro

Classification of broadband echoes from prey of a foraging Blainville's beaked whale

Author Posting. © Acoustical Society of America, 2008. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 123 (2008): 1753-1762, doi:10.1121/1.2828210.Blainville's beaked whales (Mesoplodon densirostris) use broadband, ultrasonic echolocation signals with a −10 dB bandwidth from 26 to 51 kHz to search for, localize, and approach prey that generally consist of mid-water and deep-water fishes and squid. Although it is well known that the spectral characteristics of broadband echoes from marine organisms vary as a function of size, shape, orientation, and anatomical group, there is little evidence as to whether or not free-ranging toothed whales use spectral cues in discriminating between prey and nonprey. In order to study the prey-classification process, a stereo acoustic tag was deployed on a Blainville's beaked whale so that emitted clicks and the corresponding echoes from targets in the water could be recorded. A comparison of echoes from targets apparently selected by the whale and those from a sample of scatterers that were not selected suggests that spectral features of the echoes, target strengths, or both may have been used by the whale to discriminate between echoes. Specifically, the whale appears to favor targets with one or more nulls in the echo spectra and to seek prey with higher target strengths at deeper depths.Field work was supported by the U.S. National Oceanographic Partnership Program, the U.S. Office of Naval Research, and the Canary Islands government. Analysis of the data was supported by the Office of the Oceanographer of the U.S. Navy, The Academic Programs Office at the Woods Hole Oceanographic Institution and the Danish Natural Science Research Council through a Steno scholarship to Peter T. Madsen

Bottlenose dolphin mothers modify signature whistles in the presence of their own calves

PLT received support from ONR grants N00014-18-1-2062 and N00014-20-1-2709. Financial support for the whistle database project has come from the Protect Wild Dolphins fund at Harbor Branch Oceanographic Institute, Vulcan Machine Learning Center for Impact, Allen Institute for Artificial Intelligence, Adelaide M. & Charles B. Link Foundation, and Dolphin Quest, Inc.Human caregivers interacting with children typically modify their speech in ways that promote attention, bonding, and language acquisition. Although this “motherese,” or child-directed communication (CDC), occurs in a variety of human cultures, evidence among nonhuman species is very rare. We looked for its occurrence in a nonhuman mammalian species with long-term mother–offspring bonds that is capable of vocal production learning, the bottlenose dolphin (Tursiops truncatus). Dolphin signature whistles provide a unique opportunity to test for CDC in nonhuman animals, because we are able to quantify changes in the same vocalizations produced in the presence or absence of calves. We analyzed recordings made during brief catch-and-release events of wild bottlenose dolphins in waters near Sarasota Bay, Florida, United States, and found that females produced signature whistles with significantly higher maximum frequencies and wider frequency ranges when they were recorded with their own dependent calves vs. not with them. These differences align with the higher fundamental frequencies and wider pitch ranges seen in human CDC. Our results provide evidence in a nonhuman mammal for changes in the same vocalizations when produced in the presence vs. absence of offspring, and thus strongly support convergent evolution of motherese, or CDC, in bottlenose dolphins. CDC may function to enhance attention, bonding, and vocal learning in dolphin calves, as it does in human children. Our data add to the growing body of evidence that dolphins provide a powerful animal model for studying the evolution of vocal learning and language.Publisher PDFPeer reviewe

Creep resisting steels, nanoparticles, interparticles matrix stresses, mobile dislocations motion and creep rate

Development of improved equation for better accuracy of calculation of stationary creep rate of creep resisting steels. Effect of acting stress components in particles disjunction matrix. Effect of increase of number of ferrite lattice vacancies