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Kit M Kovacs - One of the best experts on this subject based on the ideXlab platform.
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Bearded Seal (Erignathus barbatus) vocalizations across seasons and habitat types in Svalbard, Norway
Polar Biology, 2021Co-Authors: Samuel M. Llobet, Christian Lydersen, Heidi Ahonen, Jørgen Berge, Rolf Ims, Kit M KovacsAbstract:Male Bearded Seals ( Erignathus barbatus ) use vocal displays to attract females and to compete with other males during the mating season. This makes it possible to monitor breeding populations of this species using passive acoustic monitoring (PAM). This study analysed year-round acoustic data records from AURAL instruments in Svalbard (Norway) to investigate seasonal variation in the acoustic presence of male Bearded Seals and the phenology of different call types (long, step and sweep trills) at three sites representing a variety of habitats with varied ice conditions. Male Bearded Seals vocalized for an extended period at a drift-ice site (Atwain; January–July) north of Spitsbergen, while the vocal season was shorter at a High Arctic land-fast-ice site (Rijpfjorden; February–June) and shorter yet again at a west-coast site that has undergone dramatic reductions in sea ice cover over the last 1.5 decades (Kongsfjorden; April–June). Generalized Additive Models showed marked seasonal segregation in the use of different trill types at Atwain, where call rates reached 400 per h, with long trills being the most numerous call type. Modest segregation of trill types was seen at Rijpfjorden, where call rates reached 300 per h, and no segregation occurred in Kongsfjorden (peak call rate 80 per h). Sea ice cover was available throughout the vocal season at Atwain and Rijpfjorden, while at Kongsfjorden peak vocal activity (May–June) occurred after the sea ice disappeared. Ongoing climate warming and sea ice reductions will likely increase the incidence of such mismatches and reduce breeding habitat for Bearded Seals.
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First isolation of Brucella pinnipedialis and detection of Brucella antibodies from Bearded Seals Erignathus barbatus.
Diseases of aquatic organisms, 2018Co-Authors: Geoffrey Foster, Kit M Kovacs, Ingebjørg Helena Nymo, Kimberlee B. Beckmen, Andrew Brownlow, Johanna L. Baily, Mark P. Dagleish, Jakub Muchowski, Lorraine L. Perrett, Morten TrylandAbstract:Brucella species infecting marine mammals was first reported in 1994 and in the years since has been documented in various species of pinnipeds and cetaceans. While these reports have included species that inhabit Arctic waters, the few available studies on Bearded Seals Erignathus barbatus have failed to detect Brucella infection to date. We report the first isolation of Brucella pinnipedialis from a Bearded Seal. The isolate was recovered from the mesenteric lymph node of a Bearded Seal that stranded in Scotland and typed as ST24, a sequence type associated typically with pinnipeds. Furthermore, serological studies of free-ranging Bearded Seals in their native waters detected antibodies to Brucella in Seals from the Chukchi Sea (1990-2011; 19%) and Svalbard (1995-2007; 8%), whereas no antibodies were detected in Bearded Seals from the Bering Sea or Bering Strait or from captive Bearded Seals.
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Optimal state-space modelled (SSM) Argos location data (black) overlaid with GPS locations (red) for the focal A) Bearded Seal and B) ringed Seal.
2015Co-Authors: Andrew D. Lowther, Christian Lydersen, Mike A. Fedak, Phil Lovell, Kit M KovacsAbstract:* denotes optimal model was constructed using the error structures derived from data in [10]. Modelled location and GPS point estimates are shown as black and red dots, respectively. For each tripEstimation model, the underlying time-spent along the full path estimate is shown in purple (obscured in the Bearded Seal plot in favour of displaying point estimates). Black boxes highlight areas of departure by each model from the true path. Modelled location estimates for the Bearded Seal fitted well with GPS locations with the exception of two areas, at the very northerly edge of its trajectory, and just south of Prins Karls Forland. Note the sparse numbers of GPS location estimates for the ringed Seal, particularly during transit movements between fjords. Although there were ~50% fewer Argos location estimates for the ringed Seal, all models reconstructed some aspects of these transit movements despite showing a number of erroneous land locations. The exception was the tripEstimation modelled data, presumably due to the effects of incorporating a land mask during the modelling process.
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Root Mean Square Error (RMSE) estimates (km) between modelled Argos locations and the true (GPS) position at varying sensitivities for three commonly-used location error correction models freely-available within the R statistical framework; crawl [14
2015Co-Authors: Andrew D. Lowther, Christian Lydersen, Mike A. Fedak, Phil Lovell, Kit M KovacsAbstract:‘Old’ and ‘New’ reflect the effect of applying the original error structures derived from data in [10] and errors estimated from data in the present study, respectively. Variable ‘N’ for the tripEstimation results reflects the reduction in the pre-processed dataset. For all models, the new error structures incorporated a correction for differences in the distance covered by one degree of longitude at high latitude was applied. Optimal model results are highlighted in bold italics. Both bsam and tripEstimation models performed better with error structures derived from the current study, providing the most accurate location estimates at the lowest speed threshold with the exception of the Bearded Seal bsam model. Sensitivity of models to different speed thresholds was apparent, though the differences in error estimates were minimal.Root Mean Square Error (RMSE) estimates (km) between modelled Argos locations and the true (GPS) position at varying sensitivities for three commonly-used location error correction models freely-available within the R statistical framework; crawl [14], bsam [17] and tripEstimation [31].
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Diving behavior and swimming style of nursing Bearded Seal pups
Marine Ecology Progress Series, 2009Co-Authors: Yuuki Y. Watanabe, Christian Lydersen, Katsufumi Sato, Yasuhiko Naito, Nobuyuki Miyazaki, Kit M KovacsAbstract:Seals are born on land or ice and must acquire the diving and swimming skills required to forage and avoid predators during their early lives. While diving behavior, including swim speed and swimming style (e.g. prolonged gliding and stroke-and-glide swimming), of adult Seals is well documented, knowledge regarding the diving behavior of pups is still limited to records of dive depth and duration measured by simple time-depth recorders. In the present study, we attached multi- sensor data loggers to 6 Bearded Seal Erignathus barbatus pups weighing between 33 kg (newborn) and 104 kg (close to weaning). The mean swim speed and the mean distance covered by a stroke cycle was lowest (0.5 m s -1 and 0.3 m, respectively) in the smallest pup and highest (0.9 m s -1 and 0.6 m) in the largest pup. The largest pup showed substantial periods (17% of transit time) of prolonged gliding, as adult Seals commonly do. However, the 3 medium-sized pups glided only during
Christian Lydersen - One of the best experts on this subject based on the ideXlab platform.
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Bearded Seal (Erignathus barbatus) vocalizations across seasons and habitat types in Svalbard, Norway
Polar Biology, 2021Co-Authors: Samuel M. Llobet, Christian Lydersen, Heidi Ahonen, Jørgen Berge, Rolf Ims, Kit M KovacsAbstract:Male Bearded Seals ( Erignathus barbatus ) use vocal displays to attract females and to compete with other males during the mating season. This makes it possible to monitor breeding populations of this species using passive acoustic monitoring (PAM). This study analysed year-round acoustic data records from AURAL instruments in Svalbard (Norway) to investigate seasonal variation in the acoustic presence of male Bearded Seals and the phenology of different call types (long, step and sweep trills) at three sites representing a variety of habitats with varied ice conditions. Male Bearded Seals vocalized for an extended period at a drift-ice site (Atwain; January–July) north of Spitsbergen, while the vocal season was shorter at a High Arctic land-fast-ice site (Rijpfjorden; February–June) and shorter yet again at a west-coast site that has undergone dramatic reductions in sea ice cover over the last 1.5 decades (Kongsfjorden; April–June). Generalized Additive Models showed marked seasonal segregation in the use of different trill types at Atwain, where call rates reached 400 per h, with long trills being the most numerous call type. Modest segregation of trill types was seen at Rijpfjorden, where call rates reached 300 per h, and no segregation occurred in Kongsfjorden (peak call rate 80 per h). Sea ice cover was available throughout the vocal season at Atwain and Rijpfjorden, while at Kongsfjorden peak vocal activity (May–June) occurred after the sea ice disappeared. Ongoing climate warming and sea ice reductions will likely increase the incidence of such mismatches and reduce breeding habitat for Bearded Seals.
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Optimal state-space modelled (SSM) Argos location data (black) overlaid with GPS locations (red) for the focal A) Bearded Seal and B) ringed Seal.
2015Co-Authors: Andrew D. Lowther, Christian Lydersen, Mike A. Fedak, Phil Lovell, Kit M KovacsAbstract:* denotes optimal model was constructed using the error structures derived from data in [10]. Modelled location and GPS point estimates are shown as black and red dots, respectively. For each tripEstimation model, the underlying time-spent along the full path estimate is shown in purple (obscured in the Bearded Seal plot in favour of displaying point estimates). Black boxes highlight areas of departure by each model from the true path. Modelled location estimates for the Bearded Seal fitted well with GPS locations with the exception of two areas, at the very northerly edge of its trajectory, and just south of Prins Karls Forland. Note the sparse numbers of GPS location estimates for the ringed Seal, particularly during transit movements between fjords. Although there were ~50% fewer Argos location estimates for the ringed Seal, all models reconstructed some aspects of these transit movements despite showing a number of erroneous land locations. The exception was the tripEstimation modelled data, presumably due to the effects of incorporating a land mask during the modelling process.
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Root Mean Square Error (RMSE) estimates (km) between modelled Argos locations and the true (GPS) position at varying sensitivities for three commonly-used location error correction models freely-available within the R statistical framework; crawl [14
2015Co-Authors: Andrew D. Lowther, Christian Lydersen, Mike A. Fedak, Phil Lovell, Kit M KovacsAbstract:‘Old’ and ‘New’ reflect the effect of applying the original error structures derived from data in [10] and errors estimated from data in the present study, respectively. Variable ‘N’ for the tripEstimation results reflects the reduction in the pre-processed dataset. For all models, the new error structures incorporated a correction for differences in the distance covered by one degree of longitude at high latitude was applied. Optimal model results are highlighted in bold italics. Both bsam and tripEstimation models performed better with error structures derived from the current study, providing the most accurate location estimates at the lowest speed threshold with the exception of the Bearded Seal bsam model. Sensitivity of models to different speed thresholds was apparent, though the differences in error estimates were minimal.Root Mean Square Error (RMSE) estimates (km) between modelled Argos locations and the true (GPS) position at varying sensitivities for three commonly-used location error correction models freely-available within the R statistical framework; crawl [14], bsam [17] and tripEstimation [31].
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The prevalence of Toxoplasma gondii in polar bears and their marine mammal prey: evidence for a marine transmission pathway?
Polar Biology, 2010Co-Authors: S. K. Jensen, Christian Lydersen, K. M. Kovacs, Jon Aars, K. ÅsbakkAbstract:Little is known about the prevalence of the parasite Toxoplasma gondii in the arctic marine food chain of Svalbard, Norway. In this study, plasma samples were analyzed for T. gondii antibodies using a direct agglutination test. Antibody prevalence was 45.6% among polar bears ( Ursus maritimus ), 18.7% among ringed Seals ( Pusa hispida ) and 66.7% among adult Bearded Seals ( Erignathus barbatus ) from Svalbard, but no sign of antibodies were found in Bearded Seal pups, harbour Seals ( Phoca vitulina ), white whales ( Delphinapterus leucas ) or narwhals ( Monodon monoceros ) from the same area. Prevalence was significantly higher in male polar bears (52.3%) compared with females (39.3%), likely due to dietary differences between the sexes. Compared to an earlier study, T. gondii prevalence in polar bears has doubled in the past decade. Consistently, an earlier study on ringed Seals did not detect T. gondii . The high recent prevalence in polar bears, ringed Seals and Bearded Seals could be caused by an increase in the number or survivorship of oocysts being transported via the North Atlantic Current to Svalbard from southern latitudes. Warmer water temperatures have led to influxes of temperate marine invertebrate filter-feeders that could be vectors for oocysts and warmer water is also likely to favour higher survivorship of oocycts. However, a more diverse than normal array of migratory birds in the Archipelago recently, as well as a marked increase in cruise-ship and other human traffic are also potential sources of T. gondii .
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Diving behavior and swimming style of nursing Bearded Seal pups
Marine Ecology Progress Series, 2009Co-Authors: Yuuki Y. Watanabe, Christian Lydersen, Katsufumi Sato, Yasuhiko Naito, Nobuyuki Miyazaki, Kit M KovacsAbstract:Seals are born on land or ice and must acquire the diving and swimming skills required to forage and avoid predators during their early lives. While diving behavior, including swim speed and swimming style (e.g. prolonged gliding and stroke-and-glide swimming), of adult Seals is well documented, knowledge regarding the diving behavior of pups is still limited to records of dive depth and duration measured by simple time-depth recorders. In the present study, we attached multi- sensor data loggers to 6 Bearded Seal Erignathus barbatus pups weighing between 33 kg (newborn) and 104 kg (close to weaning). The mean swim speed and the mean distance covered by a stroke cycle was lowest (0.5 m s -1 and 0.3 m, respectively) in the smallest pup and highest (0.9 m s -1 and 0.6 m) in the largest pup. The largest pup showed substantial periods (17% of transit time) of prolonged gliding, as adult Seals commonly do. However, the 3 medium-sized pups glided only during
Lily Gadamus - One of the best experts on this subject based on the ideXlab platform.
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Developing Theoretical Marine Habitat Suitability Models from Remotely-Sensed Data and Traditional Ecological Knowledge
Remote Sensing, 2015Co-Authors: Patrick M. Olsen, Crystal A. Kolden, Lily GadamusAbstract:There is a lack of information regarding critical habitats for many marine species, including the Bearded Seal, an important subsistence species for the indigenous residents of Arctic regions. A systematic approach to modeling marine mammal habitat in arctic regions using the lifetime and multi-generational Traditional Ecological Knowledge (TEK) of Alaska Native hunters is developed to address this gap. The approach uses lifetime and cross-generational knowledge of subsistence hunters and their harvest data in the place of observational knowledge gained from Western scientific field surveys of marine mammal sightings. TEK information for mid-June to October was transformed to Seal presence/pseudo-absence and used to train Classification Tree Analyses of environmental predictor variables to predict suitable habitat for Bearded Seals in the Bering Strait region. Predictor variables were derived from a suite of terrestrial, oceanic, and atmospheric remote sensing products, transformed using trend analysis techniques, and aggregated. A Kappa of 0.883 was achieved for habitat classifications. The TEK information used is spatially restricted, but provides a viable, replicable data source that can replace or complement Western scientific observational data.
David E. Hannay - One of the best experts on this subject based on the ideXlab platform.
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Underwater acoustic behavior of Bearded Seals (Erignathus barbatus) in the northeastern Chukchi Sea, 2007–2010
Marine Mammal Science, 2015Co-Authors: Heloise Frouin-mouy, Xavier Mouy, Bruce Martin, David E. HannayAbstract:Bearded Seal (Erignathus barbatus) calls were recorded using autonomous passive acoustic recorders deployed in the northeastern Chukchi Sea between October 2007 and October 2010. Continuous acoustic data were acquired during summer (August to mid-October), and overwinter data (mid-October through July) were acquired on a duty cycle of 40/48 min every 4 h. We investigated the spatio-temporal distribution and acoustic behavior of vocalizing Bearded Seals in this multiyear data set. Peaks in calling occurred in spring, coinciding with the mating period, and calls stopped abruptly in late June/early July. Fewer calls were detected in summer, and the vocal presence of Seals increased with the formation of pack ice in winter. Vocal activity was higher at night than during the day, with a peak around 0400 (AKST). Monthly patterns in proportional use of each call type and call duration were examined for the first time. The proportion and duration of AL1(T) and AL2(T) call types increased during the mating period, suggesting that males advertise their breeding condition by producing those specific longer trills. The observed seasonal and diel trends were consistent between years. These results improve our understanding of occurrence and acoustic behavior of Bearded Seals across the northeastern Chukchi Sea.
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Spatio-temporal distribution of ice Seals in the Chukchi Sea using underwater vocalizations: Special focus on male Bearded Seals
The Journal of the Acoustical Society of America, 2012Co-Authors: Heloise Frouin, Xavier Mouy, Julien Delarue, Bruce Martin, David E. HannayAbstract:Underwater vocalizations of ringed, ribbon and Bearded Seals were recorded over a wide region of the northeastern Chukchi Sea between July 2007 and October 2011. Ringed Seals were identified by their barks and yelps, ribbon Seals by their sweeps and puffing sounds and Bearded Seals by their trills, ascents and moans. Ringed Seal vocalizations were detected in all months of the year, whereas vocalizations from ribbon Seals occurred only in October and November. To determine the seasonal variation in the frequency of occurrence of male Bearded Seal vocalizations throughout a year 20-min recordings were analyzed to determine call counts between 02:00 and 06:00 every 3 days. Bearded Seal acoustic detections increased progressively from August to March, peaked between April and June but were essentially absent in July. Outside of the mating period (April - June) the frequency of occurrence of vocalizations varied on a diel cycle and was higher during periods of darkness. To determine the influence of diel cycle, the duration of vocalizations and the proportion of each vocal type throughout the mating season 10-min recordings on a 17-20% duty cycle were analysed between April and June every 10 days. Results are currently under review and will be presented.
Ian Stirling - One of the best experts on this subject based on the ideXlab platform.
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ARCTIC Underwater Vocalizations as a Tool for Studying the Distribution and Relative Abundance of Wintering Pinnipeds in the High Arctic
2015Co-Authors: Ian Stirling, Wendy Calvert, Holly CleatorzAbstract:~~.Recordingsofthebeundenvatervacpl izat ionsofr iasedsc l l s,~~sandw~wertmdeintheHighArct icbetweMlate Marchandlatelune 19800ad1~1, toevrkutt thepoecmi. l faus iogsub- iœvocPl iPt ionstoeturLytbe~~andrve~ofwiater-mgpirmipeds.MostofthecPllsmedebythesethnespccies~iderrtifKdandoninittrlkxiconis~.Ringedse;llvocalizationswererorefre-qumtinlateAprilthancarlierinthescPsonorin~Juae,wbmasthehicdvocaliPtioarateerecordedforbcnrdcdsePlswereinlateJune. Vocalization rates of all thra: species were i n d i i v e oftheir diatfbutim and dative rbundpncc in different areas and sea ice habitat types. We con-cIudethatuadematervocalizationshavc~potentklforgivinsmonpncise~~onthcrel.t iveabundPmxofwinteringpianipadsthan technique for censusing. Key words: vocalizations, ringed Seal, Bearded Seal, walrus, distribution &SUMk. Les vocalisations sous-marines de phoques annelts, de phcques barbus et de morses ont &6 euregides dans le nord de l’Arctique entr
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Individual patterns of prey selection and dietary specialization in an Arctic marine carnivore
Oikos, 2011Co-Authors: Gregory W. Thiemann, Ian Stirling, Sara J. Iverson, Martyn E. ObbardAbstract:The cumulative effect of individual-level foraging patterns may have important consequences for ecosystem functioning, population dynamics and conservation. Dietary specialization, whereby an individual exploits a subset of resources available to the rest of the population, can develop in response to environmental or intrinsic population factors. However, accurate assessment of individual diets may be difficult because analyses of recent food intake may misrepresent foraging variability within a heterogeneous environment. We used quantitative fatty acid signature analysis (QFASA) and a novel index of longitudinal dietary change to examine the individual foraging patterns of 64 polar bears Ursus maritimus successively sampled in Western and Southern Hudson Bay between 1994–2003. Estimated diets varied between and within age and sex classes, with adult male polar bears consuming significantly more Bearded Seal Erignathus barbatus than adult female or subadult bears, whose diets were dominated by ringed Seal Pusa hispida. Among individual adult males, consumption of Bearded Seal accounted for 0–98% of the diet and Bearded Seal consumption was positively correlated with individual dietary specialization, as measured by proportional similarity (PSi) to the rest of the population. Most individual diets were consistent from year-to-year and were therefore not a product of short-term heterogeneity in prey distribution. However, a novel dietary change index indicated that adult male polar bears had the most temporally variable diets with 23% of adult males switching their diet from predominantly ringed Seal to predominantly Bearded Seal or vice versa. We conclude that QFASA is well-suited to analyses of individual-level foraging because it reflects an animal’s diet over the preceding weeks to months. The subpopulations of bears in this study were near the southern limit of their species range and have experienced negative individual- and population-level impacts related to sea ice loss and climate warming. The tightly constrained diets of some individuals, particularly adult females and subadults, may make them especially sensitive to future climate change.
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Population structure of ice-breeding Seals.
Molecular ecology, 2008Co-Authors: Corey S. Davis, Ian Stirling, Curtis Strobeck, David W. ColtmanAbstract:The development of population genetic structure in ice-breeding Seal species is likely to be shaped by a combination of breeding habitat and life-history characteristics. Species that return to breed on predictable fast-ice locations are more likely to exhibit natal fidelity than pack-ice-breeding species, which in turn facilitates the development of genetic differentiation between subpopulations. Other aspects of life history such as geographically distinct vocalizations, female gregariousness, and the potential for polygynous breeding may also facilitate population structure. Based on these factors, we predicted that fast-ice-breeding Seal species (the Weddell and ringed Seal) would show elevated genetic differentiation compared to pack-ice-breeding species (the leopard, Ross, crabeater and Bearded Seals). We tested this prediction using microsatellite analysis to examine population structure of these six ice-breeding species. Our results did not support this prediction. While none of the Antarctic pack-ice species showed statistically significant population structure, the Bearded Seal of the Arctic pack ice showed strong differentiation between subpopulations. Again in contrast, the fast-ice-breeding Weddell Seal of the Antarctic showed clear evidence for genetic differentiation while the ringed Seal, breeding in similar habitat in the Arctic, did not. These results suggest that the development of population structure in ice-breeding phocid Seals is a more complex outcome of the interplay of phylogenetic and ecological factors than can be predicted on the basis of breeding substrate and life-history characteristics.
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quantifying the sensitivity of arctic marine mammals to climate induced habitat change
Ecological Applications, 2008Co-Authors: Kristin L. Laidre, Ian Stirling, Øystein Wiig, Lloyd F Lowry, M P Heidejorgensen, Steven H. FergusonAbstract:We review seven Arctic and four subarctic marine mammal species, their habitat requirements, and evidence for biological and demographic responses to climate change. We then describe a pan-Arctic quantitative index of species sensitivity to climate change based on population size, geographic range, habitat specificity, diet diversity, migration, site fidelity, sensitivity to changes in sea ice, sensitivity to changes in the trophic web, and maximum population growth potential (Rmax). The index suggests three types of sensitivity based on: (1) narrowness of distribution and specialization in feeding, (2) seasonal dependence on ice, and (3) reliance on sea ice as a structure for access to prey and predator avoidance. Based on the index, the hooded Seal, the polar bear, and the narwhal appear to be the three most sensitive Arctic marine mammal species, primarily due to reliance on sea ice and specialized feeding. The least sensitive species were the ringed Seal and Bearded Seal, primarily due to large circumpolar distributions, large population sizes, and flexible habitat requirements. The index provides an objective framework for ranking species and focusing future research on the effects of climate change on Arctic marine mammals. Finally, we distinguish between highly sensitive species and good indicator species and discuss regional variation and species-specific ecology that confounds Arctic-wide generalization regarding the effects of climate change.
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Haul-out behaviour of ringed and Bearded Seals in relation to defence against surface predators
Canadian Journal of Zoology, 1991Co-Authors: Michael C.s. Kingsley, Ian StirlingAbstract:The ringed Seal, Phoca hispida, hauls out at the edge of self-maintained breathing holes or narrow cracks, either in fast ice or in the centre of large floes in pack ice, apparently because this reduces its vulnerability to capture by polar bears, Ursus maritimus. Antipredator behaviour of ringed Seals at haul-out sites also includes lying facing both their breathing hole and downwind, and vigilance. The much larger Bearded Seal, Erignathus barbatus, hauls out on the edges of wide leads or large holes in the ice, or on the points of small ice floes, and also faces both the water and downwind. Ice-associated Seals which are not threatened by surface predators do not show these behaviour patterns.