195 research outputs found

    Orchestration : the movement and vocal behavior of free-ranging Norwegian killer whales (Orcinus orca)

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    Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2008Studying the social and cultural transmission of behavior among animals helps to identify patterns of interaction and information content flowing between individuals. Killer whales are likely to acquire traits culturally based on their population-specific feeding behaviors and group-distinctive vocal repertoires. I used digital tags to explore the contributions of individual Norwegian killer whales to group carousel feeding and the relationships between vocal and non-vocal activity. Periods of tail slapping to incapacitate herring during feeding were characterized by elevated movement variability, heightened vocal activity and call types containing additional orientation cues. Tail slaps produced by tagged animals were identified using a rapid pitch change and occurred primarily within 20m of the surface. Two simultaneously tagged animals maneuvered similarly when tail slapping within 60s of one another, indicating that the position and composition of the herring ball influenced their behavior. Two types of behavioral sequence preceding the tight circling of carousel feeding were apparent. First, the animals engaged in periods of directional swimming. They were silent in 2 of 3 instances, suggesting they may have located other foraging groups by eavesdropping. Second, tagged animals made broad horizontal loops as they dove in a manner consistent with corralling. All 4 of these occasions were accompanied by vocal activity, indicating that this and tail slapping may benefit from social communication. No significant relationship between the call types and the actual movement measurements was found. Killer whale vocalizations traditionally have been classified into discrete call types. Using human speech processing techniques, I considered that calls are alternatively comprised of shared segments that can be recombined to form the stereotyped and variable repertoire. In a classification experiment, the characterization of calls using the whole call, a set of unshared segments, or a set of shared segments yielded equivalent performance. The shared segments required less information to parse the same vocalizations, suggesting a more parsimonious system of representation. This closer examination of the movements and vocalizations of Norwegian killer whales, combined with future work on ontogeny and transmission, will inform our understanding of whether and how culture plays a role in achieving population-specific behaviors in this species.Funding sources: The Ocean Life Institute at WHOI and the National Geographic Society, the National Defense Science and Engineering Graduate Fellowship, a National Science Foundation Graduate Fellowship, the Academic Programs Office at WHOI and Dennis McLaughlin at MIT

    Sound use, sequential behavior and ecology of foraging bottlenose dolphins, Tursiops truncatus

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    Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 1999Odontocetes are assumed to use echolocation for navigation and foraging, but neither of these uses of biosonar has been conclusively demonstrated in free-ranging animals. Many bats are known to use echolocation throughout foraging sequences, changing the structure and timing of clicks as they progress towards prey capture. For odontocetes, however, we do not know enough about their foraging behavior to describe such sequences. To conduct detailed behavioral observations of any subject animal, the observer must be able to maintain continuous visual contact with the subject for a period commensurate with the duration of the behavior(s) of interest. Behavioral studies of cetaceans, which spend approximately 95% of their time below the water's surface, have been limited to sampling surface behavior except in special circumstances, e.g. clear-water environments, or with the use of technological tools. I addressed this limitation through development of an observation platform consisting of a remote controlled video camera suspended from a tethered airship with boat-based monitoring, adjustment, and recording of video. The system was used successfully to conduct continuous behavioral observations of bottlenose dolphins in the Sarasota Bay, FL area. This system allowed me to describe previously unreported foraging behaviors and elucidate functions for behaviors already defined but poorly understood. Dolphin foraging was modeled as a stage-structured sequence of behaviors, with the goal-directed feeding event occurring at the end of a series of search, encounter, and pursuit behaviors. The behaviors preceding a feeding event do not occur in a deterministic sequence, but are adaptive and plastic. A single-step transition analysis beginning with prey capture and receding in time has identified significant links between observed behaviors and demonstrated the stage-structured nature of dolphin foraging. Factors affecting the occurrence of specific behaviors and behavioral transitions include mesoscale habitat variation and individual preferences. The role of sound in foraging, especially echolocation, is less well understood than the behavioral component. Recent studies have explored the use of echolocation in captive odontocete foraging and presumed feeding in wild animals, but simultaneous, detailed behavioral and acoustic observations have eluded researchers. The current study used two methods to obtain acoustic data. The overhead video system includes two towed hydrophones used to record 'ambient' sounds of dolphin foraging. The recordings are of the 'ambient' sounds because the source of the sounds, i.e. animal, could not be localized. Many focal follows, however, were conducted with single animals, and from these records the timing of echolocation and other sounds relative to the foraging sequence could be examined. The 'ambient' recordings revealed that single animals are much more vocal than animals in groups, both overall and during foraging. When not foraging, single animals vocalized at a rate similar to the per animal rate in groups of ≥2 animals. For single foraging animals, the use of different sound types varies significantly by the habitat in which the animal is foraging. These patterns of use coupled with the characteristics of the different sound types suggest specific functions for each. The presence of multiple animals in a foraging group apparently reduces the need to vocalize, and potential reasons for this pattern are discussed. In addition, the increased vocal activity of single foraging animals lends support to specific hypotheses of sound use in bottlenose dolphins and odontocetes in general. The second acoustic data collection method records sounds known to be from a specific animal. An acoustic recording tag was developed that records all sounds produced by an animal including every echolocation click. The tag also includes an acoustic sampling interval controller and a sensor suite that measures pitch, roll, heading, and surfacing events. While no foraging events occurred while an animal was wearing an acoustic data logger, the rates of echolocation and whistling during different activities, e.g. traveling, were measured.This work was supported by the Education Office of the Woods Hole Oceanographic Institution, two grants from the Rinehart Coastal Research Center, the Ocean Ventures Fund; WHOI Sea Grant, ONR Grant #N00014-94-1-0692 to P. Tyack, and a Graduate Fellowship from the Office of Naval Research

    Movement and vocal behavior of free-ranging Norwegian killer whales (Orcinus orca)

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    Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2008.Includes bibliographical references.Studying the social and cultural transmission of behavior among animals helps to identify patterns of interaction and information content flowing between individuals. Killer whales are likely to acquire traits culturally based on their population-specific feeding behaviors and group-distinctive vocal repertoires. I used digital tags to explore the contributions of individual Norwegian killer whales to group carousel feeding and the relationships between vocal and non-vocal activity. Periods of tail slapping to incapacitate herring during feeding were characterized by elevated movement variability, heightened vocal activity and call types containing additional orientation cues. Tail slaps produced by tagged animals were identified using a rapid pitch change and occurred primarily within 20m of the surface. Two simultaneously tagged animals maneuvered similarly when tail slapping within 60s of one another, indicating that the position and composition of the herring ball influenced their behavior. Two types of behavioral sequence preceding the tight circling of carousel feeding were apparent. First, the animals engaged in periods of directional swimming. They were silent in 2 of 3 instances, suggesting they may have located other foraging groups by eavesdropping. Second, tagged animals made broad horizontal loops as they dove in a manner consistent with corralling. All 4 of these occasions were accompanied by vocal activity, indicating that this and tail slapping may benefit from social communication. No significant relationship between the call types and the actual movement measurements was found. Killer whale vocalizations traditionally have been classified into discrete call types. Using human speech processing techniques, I considered that calls are alternatively comprised of shared segments that can be recombined to form the stereotyped and variable repertoire.(cont.) In a classification experiment, the characterization of calls using the whole call, a set of unshared segments, or a set of shared segments yielded equivalent performance. The shared segments required less information to parse the same vocalizations, suggesting a more parsimonious system of representation. This closer examination of the movements and vocalizations of Norwegian killer whales, combined with future work on ontogeny and transmission, will inform our understanding of whether and how culture plays a role in achieving population-specific behaviors in this species.by Ari Daniel Shapiro.Ph.D

    Prepared by: Naval Facilities Engineering Command Northwest Prepared for:

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    TABLE OF CONTENTS ACRONYMS AND ABBREVIATIONS.......................................................................................... vi

    Damsels and distress: Factors affecting Haemulidae distribution on Bahamian reefs

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    The interconnected habitats of coral reefs, mangroves and seagrass are home to a quarter of all known species in the marine environment. The interconnectivity of these areas improves species richness and density, even for species that do not use the habitats as a nursery. The communities that live as part of these ecosystems, just like many other marine species, are vulnerable to the effects of anthropogenic noise. Haemulidae spp. use the patch reef system protected by the Cape of Eleuthera as an intermediate nursery and exhibit a complex relationship with Stegastes spp. The importance of coral reef flats, such as those of Eleuthera, remains a crucial knowledge gap in our understanding of the coral reef nursery ecosystem. Also lacking is an understanding of the effect of chronic boat traffic on entire coral reef fish communities. This thesis aims to address these knowledge gaps across three chapters. Chapter 1 provides a literature review exploring Haemulidae spp. in the tropical marine environment and the importance of nursery habitats; Stegastes species in the tropical marine environment; and, the effects of anthropogenic noise in the marine environment. This highlights the current knowledge gaps and guides the data chapters. Chapter 2 presents a study in the patch reef system identifying the settlement habits of three Stegastes spp. (S. leucostictus, S. diencaeus, S. partitus) and the relationship with local Haemulidae spp. populations. This study identifies that this interaction may be an indication of reef health, as well as shedding light on a competitive hierarchy that exists amongst Stegastes spp. Chapter 3 presents a community level study (53 species, 14,970 individuals, 6 patch reefs) comparing the reactions of the patch reefs either communities protected from or exposed to chronic boat traffic. The chronic effect of boat traffic had a detrimental effect on density, species richness and recruitment compared to similar reefs. This was particularly noticeable with the Haemulidae spp. using the patch reef system as an intermediate nursery. This could mean that chronic boat traffic is influencing recruitment as well as having wider implications for reef health

    Automatic Detectors for Underwater Soundscape Measurements

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    Environmental impact regulations require that marine industrial operators quantify their contribution to underwater noise scenes. Automation of such assessments becomes feasible with the successful categorisation of sounds into broader classes based on source types – biological, anthropogenic and physical. Previous approaches to passive acoustic monitoring have mostly been limited to a few specific sources of interest. In this study, source-independent signal detectors are developed and a framework is presented for the automatic categorisation of underwater sounds into the aforementioned classes

    The role of Accelerometry in the Conservation of two Coastal Marine Vertebrates

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    This thesis advances the understanding of the spatial and behavioural ecology of two endangered species, basking sharks (Cetorhinus maximus) and green turtles (Chelonia mydas) at their coastal foraging sites while highlighting the pragmatic application of biologging technology in informing conservation. Chapter 1 of this thesis is a general introduction to tracking technologies, covering how the advancements of biologging have revolutionised the field of ecology, with an emphasis on how accelerometers can be used in conservation. Chapters 2 explores the use of accelerometers on three basking sharks in the western Scottish Isles to understand their fine-scale behaviour. I present early evidence of potential behavioural lateralisation, and the first direct records of 67 breaches over 41 days, with sharks breaching on average twice a day, both during night and day and increasing energy expenditure by at least 30 times to breach. While the function of breaching remains unclear, owing to its energetic cost, breaching is likely to have an important fitness function. In Chapter 3, accelerometers were deployed on 16 juvenile green turtles in The Bahamas to investigate the behavioural and energetic costs of translocation. Turtles rehomed in as little as 15 hours following translocation of 4 km and allocated twice as much time to energetically demanding behaviours compared to resident turtles at their foraging grounds, highlighting that translocation is not a suitable conservation practice for sea turtles. Chapter 4 summarises both data chapters and discusses how their findings provide further evidence of how tracking technologies can be ideal tools for conservation practitioners by monitoring animal movement, behaviour and health as well as assisting with the designation of protected areas by identifying important life history events. Chapter 4 concludes on the challenges and limitations of the thesis as well as the future directions in the use of tracking technologies in conservation ecology
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