Patterns of mortality in endangered Cook Inlet beluga whales: Insights from pairing a long‐term photo‐identification study with stranding records

2020 ◽  
Author(s):  
Tamara L. McGuire ◽  
Kim E. W. Shelden ◽  
Gina K. Himes Boor ◽  
Amber D. Stephens ◽  
John R. McClung ◽  
...  
Polar Biology ◽  
2020 ◽  
Vol 43 (11) ◽  
pp. 1851-1871 ◽  
Author(s):  
Tamara L. McGuire ◽  
Amber D. Stephens ◽  
John R. McClung ◽  
Christopher D. Garner ◽  
Kim E. W. Shelden ◽  
...  

2021 ◽  
pp. 20-40
Author(s):  
Tamara L. McGuire ◽  
Amber D. Stephens ◽  
John R. McClung ◽  
Christopher Garner ◽  
Kathleen A. Burek-Huntington ◽  
...  

2020 ◽  
Vol 30 (12) ◽  
pp. 2402-2427 ◽  
Author(s):  
Tamara L. McGuire ◽  
Gina K. Himes Boor ◽  
John R. McClung ◽  
Amber D. Stephens ◽  
Christopher Garner ◽  
...  

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0244204
Author(s):  
Hayao Kobayashi ◽  
Hal Whitehead ◽  
Masao Amano

Little is known about the social structure of male sperm whales (Physeter macrocephalus) after they leave their natal units. While previous studies found no evidence for preferred associations among males, the observation of mass-strandings consisting exclusively of males, suggest that they have strong social bonds. To investigate the social associations among male sperm whales, we used half weight index of association, permutation tests and standardized lagged association rate models on a large photo-identification database collected between 2006 and 2017 in Nemuro Strait, Japan. Our results suggest that while male sperm whales are not as social as females, they do form long term associations, have preferred companionship, and forage in social proximity to each other. The best-fitting model to the standardized lagged association rate showed that associations among males last for at least 2.7 years and as most males leave the area after 2 years, associations may last for longer. Twenty dyads were observed associating over more than 2 years, for a maximum 5 years. One dyad was observed associating on 19 different days and clustered on 7 different days. Male associations may function to enhance foraging or to fend off predators. Such relationships seem to be adapted to a pelagic habitat with uncertain resource availability and predation pressure.


Author(s):  
Dag Vongraven ◽  
Anna Bisther

Studies in the Pacific have identified distinct killer whale ecotypes that are either specialized mammal- or fish-eaters. The different types have developed hunting strategies that would suggest specialization could be more advantageous than generalism. However, it has been suggested, based on long-term dietary markers of tooth wear and stable isotope values, that lineages in the North Atlantic are generalist, but with individual variation in the proportion of prey types consumed. Here, we present the results of ten years of observational and photo-identification data of a population of killer whales that follows the Norwegian spring-spawning stock of Atlantic herring. Although the whales were predominantly observed while feeding upon herring, one pod of herring-eating whales was also observed interacting with seals. This supports the hypothesis based on the long-term markers, of a degree of specialization, with a small number of groups persistently feeding upon mammals, but switching between herring and seals. We further investigated this prey switching by conducting playbacks of herring-eating killer whale sounds to harbour seals at haul-out sites on the herring spawning grounds. We recorded changes in behaviour consistent with an anti-predator response, suggesting the seals perceived the herring-eating killer whales as a potential predatory threat and had not habituated to their calls. This could be due to the risk of herring-eating killer whales switching to mammalian prey, or the difficulty of discriminating between killer whale pods due to the large population size and number of killer whale call dialects in this population, or a combination of both.


2016 ◽  
Vol 77 (2) ◽  
pp. 89-105 ◽  
Author(s):  
Stephanie A. Norman ◽  
Roderick C. Hobbs ◽  
Caroline E. C. Goertz ◽  
Kathy A. Burek-Huntington ◽  
Kim E. W. Shelden ◽  
...  

2016 ◽  
Vol 77 (2) ◽  
pp. 32-39 ◽  
Author(s):  
Kate S. Lomac-MacNair ◽  
Mari A. Smultea ◽  
Mark P. Cotter ◽  
Carey Thissen ◽  
Lisa Parker

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