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The rise of inexpensive, user‐friendly cameras and editing software promises to revolutionize data collection with minimal disturbance to marine mammals. Video sequences recorded by aerial drones and GoPro cameras provided close‐up views and unique perspectives of humpback whales engulfing juvenile salmon at or just below the water surface in Southeast Alaska and Prince William Sound. Although humpback feeding is famous for its flexibility, several stereotyped events were noted in the 47 lunges we analyzed. Engulfment was rapid (mean 2.07 s), and the entrance through which the tongue inverts into the ventral pouch was seen as water rushes in. Cranial elevation was a major contributor to gape, and pouch contraction sometimes began before full gape closure, with reverberating waves indicating rebounding flow of water within the expanded pouch. Expulsion of filtered water began with a small splash at the anterior of the mouth, followed by sustained excurrent flow in the mouth's central or posterior regions. Apart from a splash of rebounding water, water within the mouth was surprisingly turbulence‐free during engulfment, but submersion of the whale's head created visible surface whirlpools and vortices which may aggregate prey for subsequent engulfment.

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... Enlarged photographs are provided in Fig. S2. 60 deg) compared with mechanical tests of maximal gape angle in sei and fin whales (85-90 deg; Brodie, 2001) and photogrammetric measurements of Bryde's (80 deg; Goldbogen et al., 2007) and humpback (82.5 deg;Werth et al., 2019) whale gape angles. The whale continued to roll as the buccal cavity expanded and then the mouth began to close (Fig. 2, right, photo C). ...
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... sternomandibularis and m. depressor mandibulae muscles and with the aid of drag forces. It appears that cranial elevation also plays a role in rorqual gape opening (Arnold et al., 2005;Koolstra & van Eijden, 2004;Werth, Kosma, Chenoweth, & Straley, 2019), and that tail stock musculature provides most of the force for jaw opening during the forward locomotion propelling ram lunges. It is difficult to understand how the m. ...
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... Because the energetically costly movement of the left pectoral probably hinders the acceleration of the whale, we assert that an alternative use must be at play. We found that lunge durations of Whale A averaged 8 s, whereas Werth et al. [51] documented the mean engulfment rates from a solo humpback whale lunge to be closer to 2 s. This difference in engulfment rates with and without horizontal pectoral herding supports our hypothesis that any additional movement must substantially aid in prey capture. ...
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Drones and unmanned aerial vehicles are increasingly used in research on wildlife. Their wide applications can also give interesting insights into habitat use and population distribution. However, the disturbance they might be responsible for, on species and especially in protected areas has yet to be investigated. We assessed and compared the behavioural response of 11 southern seabird species at the Crozet Islands, Southern Indian Ocean, to drone approaches at specific altitudes. We first show that the behavioural response differed between species depending on the altitude of the drone approach. At 50 m of altitude, only one of the studied species showed a detectable reaction, whereas at 10 m, most species showed strong behavioural postures of stress. Adult penguins breeding in large colonies, and some albatross species showed little behavioural response even when the drone was as close as 3 m, whereas other species such as giant petrels or cormorants appeared highly sensitive to drone approaches. Among King Penguins, although incubating adults showed little signs of behavioural stress, non-breeding adults and fledglings in crèches exhibited strong behavioural responses to the drone approach. Monitoring heart rate allowed us to investigate the link between behavioural and physiological response to that specific potential stressor in king penguins. Whereas we confirmed the expected link between physiological and behavioural response in chicks, breeding adults showed no behavioural sign of stress but had a significant increase in heart rate, the relative increase being higher than in chicks. All together these results have important implications for the conservation of species and should be helpful for future legislations on the use of drones.
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Research on cetacean foraging ecology is central to our understanding of their spatial and behavioral ecology. Yet, functional mechanisms by which cetaceans detect prey across different scales remain unclear. Here, I postulate that cetaceans utilize a scale-dependent, multimodal sensory system to assess and increase prey encounters. I review the literature on cetacean sensory systems related to foraging ecology, and hypothesize the effective scales of each sensory modality to inform foraging opportunities. Next, I build two “scale-of-senses” schematics for the general groups of dolphins and baleen whales. These schematics illustrate the hypothetical interchange of sensory modalities used to locate and discriminate prey at spatial scales ranging from 0 m to 1,000 km: (1) vision, (2) audition (sound production and sound reception), (3) chemoreception, (4) magnetoreception, and somatosensory perception of (5) prey, or (6) oceanographic stimuli. The schematics illustrate how a cetacean may integrate sensory modalities to form an adaptive foraging landscape as a function of distance to prey. The scale-of-senses schematic is flexible, allowing for case-specific application and enhancement with improved cetacean sensory data. The framework serves to improve our understanding of functional cetacean foraging ecology, and to develop new hypotheses, methods, and results regarding how cetaceans forage at multiple scales.
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Humpback whales are remarkable for the behavioural plasticity of their feeding tactics and the diversity of their diets. Within the last decade at hatchery release sites in Southeast Alaska, humpback whales have begun exploiting juvenile salmon, a previously undocumented prey. The anthropogenic source of these salmon and their important contribution to local fisheries makes the emergence of humpback whale predation a concern for the Southeast Alaska economy. Here, we describe the frequency of observing humpback whales, examine the role of temporal and spatial variables affecting the probability of sighting humpback whales and describe prey capture behaviours at five hatchery release sites. We coordinated twice-daily 15 min observations during the spring release seasons 2010–2015. Using logistic regression, we determined that the probability of occurrence of humpback whales increased after releases began and decreased after releases concluded. The probability of whale occurrence varied among release sites but did not increase significantly over the 6 year study period. Whales were reported to be feeding on juvenile chum, Chinook and coho salmon, with photographic and video records of whales feeding on coho salmon. The ability to adapt to new prey sources may be key to sustaining their population in a changing ocean.
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Unmanned aerial systems (UAS), commonly referred to as drones, are finding applications in several ecological research areas since remotely piloted aircraft (RPA) technology has ceased to be a military prerogative. Fixed-wing RPA have been tested for line transect aerial surveys of geographically dispersed marine mammal species. Despite many advantages, their systematic use is far from a reality. Low altitude, long endurance systems are still highly priced. Regulatory bodies also impose limitations while struggling to cope with UAS rapid technological evolution. In contrast, small vertical take-off and landing (VTOL) UAS have become increasingly affordable but lack the flight endurance required for long-range aerial surveys. Although this issue and civil aviation regulations prevent the use of VTOL UAS for marine mammal abundance estimation on a large scale, recent studies have highlighted other potential applications. The present note represents a general overview on the use of UAS as a survey tool for marine mammal studies. The literature pertaining to UAS marine mammal research applications is considered with special concern for advantages and limitations of the survey design. The use of lightweight VTOL UAS to collect marine mammal behavioral data is also discussed.
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Much is known about lunge feeding in balaenopterid whales, but many key aspects of structure, function, and behavior have not yet been explained in detail, especially with regard to concentrating, positioning, and swallowing large aggregations of prey. We describe a novel system of three integrated structural components, all of which are involved in sequential feeding activities (intraoral transport, filtration, and swallowing of prey) that follow lunge-feeding engulfment of prey-laden water in rorquals: 1) a hammock-like muscular sling comprising extrinsic lingual musculature along the midline of the ventral pouch; 2) the flattened scoop-like arrangement of caudal-most baleen plates converging in the oropharynx adjacent to the esophageal opening; and 3) a flow-diverting flange at the posterior dorsum of the lip, by a flow channel at the angle of the mouth. Subsequent to contraction of the ventral pouch and concomitant expulsion of the mouthful of ingested water, these three structures together, we contend, aid in 1) channeling prey posteriorly toward the esophageal opening; 2) concentrating prey as excess water is squeezed from (what is presumed to be) the slurry-like mixture of nektonic and/or planktonic prey and water; and 3) guiding prey into the isthmus of the fauces while simultaneously 4) facilitating expulsion of water. These related functions occur along with, and are in part achieved by, elevation and retraction of the tongue and oral floor. Given their presumed functional role these systems are best described as a suite of integrated structural adaptations. This article is protected by copyright. All rights reserved.
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The rapidly advancing field of unmanned aerial vehicle (UAV) technology is currently being used to address a wide variety of subjects regarding wildlife biology and conservation (Jones et al. 2006; Koh and Wich 2012; Hodgson et al. 2013). This technology is a highly applicable platform for identifying and monitoring sea turtles in their in-water habitat (Bevan et al. 2015) and is particularly useful for studying courtship and mating activities in sea turtles. These behaviors are often observed in nearshore areas adjacent to nesting beaches, near or at the water’s surface, and can occur over prolonged periods of time (e.g., mating behavior in Green Turtles can last over multiple hours; Wood and Wood 1980). Additionally, surveys using UAV technology can be used for identifying critical habitat and areas used for courtship and mating activities in endangered sea turtles, while reducing the overall time, effort, and cost that has traditionally been required to conduct manned boat- and airplane-based surveys. A variety of both fixed-wing and rotorcraft UAV designs are currently available and each offers distinct capabilities that should be considered when deciding on which aircraft to use in a specific project. As an example, fixed-wing aircraft typically have longer flight durations, but do not have the ability to stop and hover above an area of interest. In contrast to traditional airplane- and boat-based surveys, as well as fixed-wing UAVs, a rotorcraft UAV provides a stable, stationary video platform that can hover directly above the behavior of interest. Therefore, upon locating sea turtles, a rotorcraft UAV can be used to hover, follow, and record video footage of their behaviors. The current study provides an evaluation of the applicability of UAVs for studying sea turtle courting and mating behavior in nearshore waters.
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Citizen science can increase the scope of research in the marine environment; however, it suffers from necessitating specialized training and simplified methodologies that reduce research output. This paper presents a simplified, novel survey methodology for citizen scientists, which combines GoPro imagery and structure from motion to construct an ortho-corrected 3D model of habitats for analysis. Results using a coral reef habitat were compared to surveys conducted with traditional snorkelling methods for benthic cover, holothurian counts, and coral health. Results were comparable between the two methods, and structure from motion allows the results to be analysed off-site for any chosen visual analysis. The GoPro method outlined in this study is thus an effective tool for citizen science in the marine environment, especially for comparing changes in coral cover or volume over time.
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Observations of non-feeding gulps in dwarf minke whales Balaenoptera acutorostrata sensu lato confirmed the axial rotation and lateral divergence (omega rotation) of the lower jaw suggested for rorquals. Gulps were either restricted to the inter-mandibular area or involved expansion of the whole ventral pouch; the extent of filling appears to be under voluntary control. Gulps may have different functions, e.g. feeding or display. Maximum gape (about 70°) occurred during inter-mandibular gulps, involving both depression of the lower jaw and elevation of the head and upper jaw. The lower jaw was depressed only to about 40°, much less than the 90° generally illustrated in the literature for rorquals. The mouth was closed as the ventral pouch was still filling; closure was rapid, associated with the moderate depression of the lower jaw. The whole ventral pouch contracted uniformly to expel water. The fibrocartilage skeleton of the ventral pouch was involved in outpocketing of the mental ("chin") region both at the beginning and end of gulps. During expulsion of water, partial axial rotation of the lower jaw maintained a groove just lateral to the baleen plates, opening as a vertical slit posteriorly. This would allow water expelled between the baleen plates to flow backwards, especially from the angle of the mouth. Incorporating these new observations, we discuss evolution of filter feeding and suggest that suction feeding was the primitive condition for baleen whales.
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Unmanned aerial systems (UAS) have the potential to collect high-resolution photographs of marine mammals for life-history studies without disturbing the species being studied. We conducted a pilot study near Igloolik, Nunavut, in early July 2013 to collect identification-quality photographs of bowhead whales and record the responses of the whales to overflights by an UAS. Operating under a restrictive line-of-sight permit from Transport Canada, we successfully collected high quality photographs of bowhead whales and none of the whales overflown responded to the overflights in an observable manner. If the UAS were operated under a beyond-line-of-sight permit, the UAS could be used to search for whales ahead of and to the side of the survey vessels making it more efficient to find whales to photograph. Even when operating under the restrictive line-of-sight permit, large numbers of whales could be photographed, which would provide important life-history information on the poorly studied Eastern Canada – West Greenland population.
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The tongue of rorqual (balaenopterid) whales slides far down the throat into the expanded oral pouch as an enormous mouthful of water is engulfed during gulp feeding. As the tongue and adjacent oral floor expands and slides caudoventrally, it glides along a more superficial (outer) layer of ventral body wall musculature, just deep to the accordion‐like ventral throat pleats. We hypothesize that this sliding movement of adjacent musculature is facilitated by a slick, stretchy layer of loose areolar connective tissue that binds the muscle fibers and reduces friction: fascia. Gross anatomical examination of the gular region of adult minke, fin, and humpback whales confirms the presence of a discrete, three‐layered sublingual fascia interposed between adhering fasciae of the tongue and body wall. Histological analysis of this sublingual fascia reveals collagen and elastin fibers loosely organized in a random feltwork along with numerous fibroblasts in a watery extracellular matrix. Biomechanical testing of tissue samples in the field and laboratory, via machine‐controlled or manual stretching, demonstrates expansion of the sublingual fascia and its three layers up to 250% beyond resting dimensions, with slightly more extension observed in anteroposterior (rather than mediolateral or oblique) stretching, and with the most superficial of the fascia's three layers. This article is protected by copyright. All rights reserved.
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Movement within and between prey patches can influence the fitness of a predator, and understanding such foraging decisions is an important topic in ecology. Most research has found sustained foraging in dense prey patches but has focused on the movement of raptorial predators that feed on single prey items, or suspension-feeders foraging on comparatively immobile zooplankton. The goal of this study was to investigate the fine-scale movement of a suspension-feeding marine vertebrate species while foraging for mobile prey. Using animal-borne tags and surface observations, we analyzed the movement of foraging humpback whales Megaptera novaeangliae within and among acoustically detected patches of sand lance Ammodytes spp. in the water column in the southern Gulf of Maine, USA. Analyzing data from 9 whales tagged between 2008 and 2012, we found hierarchical whale foraging movements that paralleled a complex, hierarchically structured prey landscape. For 7 out of 9 whales, feeding bout scales corresponded to prey patch scales. For 6 out of 9 whales, movement between sequential feeding events was not significantly different from distances between neighboring prey schools. Targeting neighboring schools during sequential feeding events, as opposed to sustained foraging in profitable patches, may increase foraging success in marine suspension-feeders targeting mobile prey, which confirms findings from many other marine predator taxa feeding on mobile prey species. Our study presents novel evidence for the high behavioral plasticity of an intermittent suspension-feeder targeting mobile prey, adapting its movement to the behavior of its prey and the structure of its prey field. © The authors 2018. Open Access under Creative Commons by Attribution Licence. Use, distribution and reproduction are unrestricted. Authors and original publication must be credited.
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The use of unoccupied aircraft systems (UASs, also known as drones) in science is growing rapidly. Recent advances in microelectronics and battery technology have resulted in the rapid development of low-cost UASs that are transforming many industries. Drones are poised to revolutionize marine science and conservation, as they provide essentially on-demand remote sensing capabilities at low cost and with reduced human risk. A variety of multirotor, fixed-wing, and transitional UAS platforms are capable of carrying various optical and physical sampling payloads and are being employed in almost every subdiscipline of marine science and conservation. This article provides an overview of the UAS platforms and sensors used in marine science and conservation missions along with example physical, biological, and natural resource management applications and typical analytical workflows. It concludes with details on potential effects of UASs on marine wildlife and a look to the future of UASs in marine science and conservation. Expected final online publication date for the Annual Review of Marine Science Volume 11 is January 3, 2019. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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The anatomy of large cetaceans has been well documented, mostly through dissection of dead specimens. However, the difficulty of studying the world's largest animals in their natural environment means the functions of anatomical structures must be inferred. Recently, non-invasive tracking devices have been developed that measure body position and orientation, thereby enabling the detailed reconstruction of underwater trajectories. The addition of cameras to the whale-borne tags allows the sensor data to be matched with real-time observations of how whales use their morphological structures, such as flukes, flippers, feeding apparatuses, and blowholes for the physiological functions of locomotion, feeding, and breathing. Here, we describe a new tag design with integrated video and inertial sensors and how it can be used to provide insights to the function of whale anatomy. This technology has the potential to facilitate a wide range of discoveries and comparative studies, but many challenges remain to increase the resolution and applicability of the data. Anat Rec, 300:1935–1941, 2017. © 2017 Wiley Periodicals, Inc.
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A central paradigm of aquatic locomotion is that cetaceans use fluke strokes to power their swimming while relying on lift and torque generated by the flippers to perform maneuvers such as rolls, pitch changes and turns [1] . Compared to other cetaceans, humpback whales (Megaptera novaeangliae) have disproportionately large flippers with added structural features to aid in hydrodynamic performance [2,3] . Humpbacks use acrobatic lunging maneuvers to attack dense aggregations of krill or small fish, and their large flippers are thought to increase their maneuverability and thus their ability to capture prey. Immediately before opening their mouths, humpbacks will often rapidly move their flippers, and it has been hypothesized that this movement is used to corral prey [4,5] or to generate an upward pitching moment to counteract the torque caused by rapid water engulfment [6] . Here, we demonstrate an additional function for the rapid flipper movement during lunge feeding: the flippers are flapped using a complex, hydrodynamically active stroke to generate lift and increase propulsive thrust. We estimate that humpback flipper-strokes are capable of producing large forward oriented forces, which may be used to enhance lunge feeding performance. This behavior is the first observation of a lift-generating flipper-stroke for propulsion cetaceans and provides an additional function for the uniquely shaped humpback whale flipper.
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Many animals invest time and energy in removing unwanted organisms from their body surface; however, the benefits of symbiotic cleaning associations to 'clients' are disputed. We used aerial (unmanned aerial vehicles, UAVs) and underwater surveys to investigate whether loggerhead sea turtles Caretta caretta actively or incidentally invested in using fish-cleaning stations at a temperate breeding area (Zakynthos, Greece), although they are expected to minimize movement to divert energy to egg development. If the former, we hypothesized that turtles would swim into the station (UAV surveys), visit multiple times and compete for access (underwater surveys). Underwater surveys showed that station location changed annually, ruling out usage of a longterm cognitive memory. UAV surveys showed that turtles began using the station immediately after mating activity decreased (mid-May), with use remaining high until females departed (July). Wind direction (primarily southerly) was correlated with the frequency of use (UAV and under - water surveys) and direction of movement through the station (from upwind to downwind); however, turtles swam actively (i.e. did not simply drift). Of the unique turtles photo-identified during underwater surveys, 25 and 18% of individuals were detected multiple times within and across surveys, respectively, with at least 2 turtles competing for access to cleaner fish in most surveys. UAV surveys showed that more turtles were present within 100 m of the station compared to the turtles detected by underwater surveys at the station, suggesting individuals may visit the station repeatedly through the day. We conclude that turtles might initially find a station incidentally; however, repeated visits and competition for access suggest that turtles receive direct (stress relief, epibiont removal) and/or indirect (health, fitness, migratory) benefits.
Article
Rorqual whales exhibit an extreme lunge filter-feeding strategy characterized by acceleration to high speed and engulfment of a large volume of prey-laden water [1–4]. Although tagging studies have quantified the kinematics of lunge feeding, the timing of engulfment relative to body acceleration has been modeled conflictingly because it could never be directly measured [5–7]. The temporal coordination of these processes has a major impact on the hydrodynamics and energetics of this high-cost feeding strategy [5–9]. If engulfment and body acceleration are temporally distinct, the overall cost of this dynamic feeding event would be minimized. However, greater temporal overlap of these two phases would theoretically result in higher drag and greater energetic costs. To address this discrepancy, we used animal-borne synchronized video and 3D movement sensors to quantify the kinematics of both the skull and body during feeding events. Krill-feeding blue and humpback whales exhibited temporally distinct acceleration and engulfment phases, with humpback whales reaching maximum gape earlier than blue whales. In these whales, engulfment coincided largely with body deceleration; however, humpback whales pursuing more agile fish demonstrated highly variable coordination of skull and body kinematics in the context of complex prey-herding techniques. These data suggest that rorquals modulate the coordination of acceleration and engulfment to optimize foraging efficiency by minimizing locomotor costs and maximizing prey capture. Moreover, this newfound kinematic diversity observed among rorquals indicates that the energetic efficiency of foraging is driven both by the whale's engulfment capacity and the comparative locomotor capabilities of predator and prey.
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Author Posting. © Society for Marine Mammalogy, 2016. This article is posted here by permission of Society for Marine Mammalogy for personal use, not for redistribution. The definitive version was published in Marine Mammal Science 32 (2016):1510–1515, doi:10.1111/mms.12328.
Article
Unmanned aerial vehicles (UAVs) have the potential to revolutionize the way research is conducted in many scientific fields [1, 2]. UAVs can access remote or difficult terrain [3], collect large amounts of data for lower cost than traditional aerial methods, and facilitate observations of species that are wary of human presence [4]. Currently, despite large regulatory hurdles [5], UAVs are being deployed by researchers and conservationists to monitor threats to biodiversity [6], collect frequent aerial imagery [7-9], estimate population abundance [4, 10], and deter poaching [11]. Studies have examined the behavioral responses of wildlife to aircraft [12-20] (including UAVs [21]), but with the widespread increase in UAV flights, it is critical to understand whether UAVs act as stressors to wildlife and to quantify that impact. Biologger technology allows for the remote monitoring of stress responses in free-roaming individuals [22], and when linked to locational information, it can be used to determine events [19, 23, 24] or components of an animal's environment [25] that elicit a physiological response not apparent based on behavior alone. We assessed effects of UAV flights on movements and heart rate responses of free-roaming American black bears. We observed consistently strong physiological responses but infrequent behavioral changes. All bears, including an individual denned for hibernation, responded to UAV flights with elevated heart rates, rising as much as 123 beats per minute above the pre-flight baseline. It is important to consider the additional stress on wildlife from UAV flights when developing regulations and best scientific practices. Copyright © 2015 Elsevier Ltd. All rights reserved.