Foraging patterns of California sea otters as indicated by telemetry

1995 ◽  
Vol 73 (3) ◽  
pp. 523-531 ◽  
Author(s):  
Katherine Ralls ◽  
Brian B. Hatfield ◽  
Donald B. Siniff
Keyword(s):  
Foraging Behavior ◽  
Prey Size ◽  
Prey Type ◽  
Dive Duration ◽  
Enhydra Lutris ◽  
Sea Otters ◽  
Foraging Patterns ◽  
Radio Transmitters ◽  
Males And Females ◽  
Juvenile Males

Foraging behavior was studied in 38 sea otters (Enhydra lutris) implanted with radio transmitters. The observed foraging behavior of instrumented individuals was similar to that of uninstrumented otters observed in previous studies: dive duration varied with prey type but not with prey size, dive success was highest for small prey, and the length of surface intervals increased with prey size. However, telemetry revealed that some otters foraged farther offshore and made longer dives than was indicated by visual observations. Individuals within age–sex classes varied in several aspects of foraging behavior, including the duration of dives and length of surface intervals. There were no overall differences between the dive durations or surface intervals during the day and during the night, though some individuals had longer dives or surface intervals during either the day or the night. There were differences in the foraging behavior of the various age–sex classes, the most striking being those between juvenile males and females. Juvenile males foraged much farther offshore [Formula: see text] in deeper water [Formula: see text] than other otters and made long dives during both the day [Formula: see text] and the night [Formula: see text]. Juvenile females fed for longer periods than other otters.

Differential Predation by Chaoborus americanus on Males and Females of Two Species of Diaptomus

1993 ◽  
Vol 50 (2) ◽  
pp. 410-415 ◽  
Author(s):  
Jules M. Blais ◽  
Edward J. Maly
Keyword(s):  
Prey Species ◽  
Calanoid Copepod ◽  
Prey Size ◽  
Handling Time ◽  
Prey Type ◽  
Feeding Rates ◽  
Feeding Experiments ◽  
Chaoborus Americanus ◽  
Differential Predation ◽  
Males And Females

Feeding experiments were performed to determine relative feeding rates of fourth-instar Chaoborus americanus larvae (Diptera) on both sexes of two calanoid copepod species, Diaptomus leptopus and D. minutus. Feeding rates, using a single prey type, showed that predation rates by Chaoborus on female D. minutus were highest, followed by male D. minutus, male D. leptopus, and female D. leptopus, respectively, when exposed to Chaoborus individually. Selectivity experiments with the four prey types made available simultaneously confirmed this pattern. Prey sizes and swimming speeds were determined, and both strike efficiency and handling time of Chaoborus were measured. Data suggested that selection between prey species was determined primarily by prey size whereas selection between sexes was determined primarily by differential swimming speed.

Novel infections of Corynosoma enhydri and Profilicollis sp. (Acanthocephala: Polymorphidae) identified in sea otters Enhydra lutris

2020 ◽  
Vol 137 (3) ◽  
pp. 239-246 ◽  
Author(s):  
KM Shanebeck ◽  
J Lakemeyer ◽  
U Siebert ◽  
K Lehnert
Keyword(s):  
Enhydra Lutris ◽  
Sea Otters

scholarly journals The historical and contemporary status of the sea otter Enhydra lutris population on Urup Island, southern Kuril Islands

Oryx ◽  
2021 ◽  
pp. 1-6
Author(s):  
Igor Popov ◽  
Alexey Scopin
Keyword(s):  
Total Population ◽  
Kuril Islands ◽  
Sea Otter ◽  
Enhydra Lutris ◽  
Sea Otters ◽  
The Past ◽  
Remote Island ◽  
Contemporary Status ◽  
Wildlife Refuges ◽  
Effective Conservation

Abstract We describe the population of the Еndangered sea otter Enhydra lutris on Urup Island, one of the main wildlife refuges in the southern Kuril Islands of Russia. We reviewed historical and local reports of the sea otter, identified its habitat around the island, and surveyed the coastal waters of the island in 2019. Sea otters were numerous on Urup Island in the past but were hunted excessively and almost exterminated by the 1950s. Since then, sea otter populations have increased, and as the island is almost uninhabited we expected otters to be numerous. This was not the case, and we estimated the total population to be 363 ± SE 126 individuals. Our observation of two skinned carcasses on the shore suggests the low numbers are a result of poaching for the illegal fur trade. The case of Urup Island demonstrates that sea otters require active conservation, as even on a remote island they remain threatened. Establishment of protected areas would be an effective conservation measure for this species, although the suppression of demand for sea otter fur is of the greatest importance.

scholarly journals Vibrissae growth rates and trophic discrimination factors in captive southern sea otters (Enhydra lutris nereis)

2013 ◽  
Vol 94 (2) ◽  
pp. 331-338 ◽  
Author(s):  
Luke P. Tyrrell ◽  
Seth D. Newsome ◽  
Marilyn L. Fogel ◽  
Marissa Viens ◽  
Roxane Bowden ◽  
...  
Keyword(s):  
Growth Rates ◽  
Enhydra Lutris ◽  
Sea Otters ◽  
Enhydra Lutris Nereis ◽  
Discrimination Factors ◽  
Trophic Discrimination

scholarly journals Foraging behavior and at-sea distribution of White-Tailed Tropicbirds in tropical ocean

2017 ◽  
Vol 78 (3) ◽  
pp. 556-563 ◽  
Author(s):  
L. F. A. S. Campos ◽  
A. B. Andrade ◽  
S. Bertrand ◽  
M. A. Efe
Keyword(s):  
Endangered Species ◽  
Foraging Behavior ◽  
Mortality Rates ◽  
Nest Attendance ◽  
Breeding Colony ◽  
Tropical Ocean ◽  
Foraging Patterns ◽  
Land Crab ◽  
Egg Consumption ◽  
Foraging Pattern

Abstract We used miniaturized GPS loggers and site observations to access foraging patterns and nest behaviour of the White-tailed Tropicbird Phaethon lepturus (WTTB), an endangered species at its South Atlantic breeding colony. Dual foraging pattern was observed with alternation between long and short foraging trips. Birds responsible for nest attendance engaged in short foraging trips with mean distance from colony of 25 ± 17 km, total distance covered of 79 ± 65 km and mean duration of 4.02 ± 5.28 hours. Birds flew by dawn and returned before dusk while partners were at sea for long foraging trips that ranged from four to 11 days, with mean maximum distance from colony of 105 ± 47.48 km. Chicks were usually left alone for hours and chick predation by Land Crab Johngartia lagostroma, egg consumption by Goniopsis cruentata and intra-specific competition are suspected to be responsible for high chick mortality rates.

The British Columbia transplant of sea otters Enhydra Lutris

1981 ◽  
Vol 20 (4) ◽  
pp. 291-295 ◽  
Author(s):  
Robert Morris ◽  
Derek V. Ellis ◽  
Brian P. Emerson
Keyword(s):  
British Columbia ◽  
Enhydra Lutris ◽  
Sea Otters

Butyltin Residues in Southern Sea Otters (Enhydra lutris nereis) Found Dead along California Coastal Waters

1998 ◽  
Vol 32 (9) ◽  
pp. 1169-1175 ◽  
Author(s):  
Kurunthachalam Kannan ◽  
Keerthi S. Guruge ◽  
Nancy J. Thomas ◽  
Shinsuke Tanabe ◽  
John P. Giesy
Keyword(s):  
Coastal Waters ◽  
Enhydra Lutris ◽  
Sea Otters ◽  
Enhydra Lutris Nereis

Summer Foraging Behaviour of Female Sea Otters (Enhydra lutris) with Pups in Simpson Bay, Alaska

2009 ◽  
Vol 35 (4) ◽  
pp. 481-489 ◽  
Author(s):  
Sylvia K. Osterrieder ◽  
Randall W. Davis
Keyword(s):  
Foraging Behaviour ◽  
Enhydra Lutris ◽  
Sea Otters

scholarly journals Predators, Disease, and Environmental Change in the Nearshore Ecosystem: Mortality in Southern Sea Otters (Enhydra lutris nereis) From 1998–2012

2020 ◽  
Vol 7 ◽  
Author(s):  
Melissa A. Miller ◽  
Megan E. Moriarty ◽  
Laird Henkel ◽  
Martin Tim Tinker ◽  
Tristan L. Burgess ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Population Level ◽  
Large Sample Size ◽  
Sea Otter ◽  
Enhydra Lutris ◽  
Sea Otters ◽  
Sarcocystis Neurona ◽  
Enhydra Lutris Nereis ◽  
Protozoal Infection ◽  
Demographic Attributes

We compiled findings from 15 years (1998–2012) of southern sea otter (Enhydra lutris nereis) necropsies, incorporating data from 560 animals. Sensitive diagnostic tests were used to detect biotoxins, bacteria, parasites and fungi. Methods to classify primary and contributing causes of death (COD) and sequelae utilized an updated understanding of health risks affecting this population. Several interesting patterns emerged, including identification of coastal regions of high mortality risk for sea otter mortality due to shark bite, cardiomyopathy, toxoplasmosis, sarcocystosis, acanthocephalan peritonitis and coccidioidomycosis. We identified demographic attributes that enhanced the risk of disease in relation to age, sex, and reproductive stage. Death due to white shark (Carcharodon carcharias) bite increased dramatically during the study period and was the most common primary COD. However, when primary and contributing COD were combined, the most prevalent COD was infectious disease (affecting 63% of otters), especially fatal infections by acanthocephalans (Profilicollis spp.) and protozoa (e.g., Sarcocystis neurona and Toxoplasma gondii). Fatal bacterial infections were also extremely common as a primary process or a sequela, affecting 68% of examined otters. Substantial advances were made in identifying sea otters that died following exposure to the pervasive marine neurotoxin domoic acid (DA), and DA intoxication was conservatively estimated as a primary or contributing COD for 20% of otters. Cardiomyopathy was also highly prevalent as a primary or contributing COD (41%) and exhibited significant associations with DA intoxication and protozoal infection. For adult and aged adult females in late pup care through post-weaning at the time of death, 83% had end lactation syndrome (ELS) as a primary or contributing COD. This comprehensive longitudinal dataset is unique in its depth and scope. The large sample size and extensive time period provided an opportunity to investigate mortality patterns in a changing environment and identify spatial and temporal disease “hot spots” and emerging threats. Our findings will help improve estimates of population-level impacts of specific threats and optimize conservation and environmental mitigation efforts for this threatened species.

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