IUCN/SSC Otter Specialist Group Bulletin

© IUCN/SCC Otter Specialist Group

Volume 31 Issue 1 (January 2014)

Abstracts

Otters and Eels: Long-Term Observations on Declines in Scotland
Pages 3 - 11 (Report)
Hans Kruuk
The summer diet of otters Lutra lutra has been monitored for almost forty years in a study area in NE Scotland. Since 2000, otter numbers and reproduction in the area have declined. At the same time the occurrence of eels (Anguilla anguilla) in otter faeces or ‘spraints’, formerly the otters’ dominant prey, decreased substantially. This is seen against a well-documented sharp, probably global decline in numbers of eel. Otter predation on young water birds in the study area increased, as has predation on other fish species, and changes in importance of other prey are also documented. It is suggested that with otters being food-limited, the decline in eels should be of serious concern to otter conservationists.
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Sprainting Into The Wind
Pages 12 - 14 (Short Note)
Hans Kruuk
Otters Lutra lutra deposited scent-marks (spraints) along a small stream in Scotland. The large majority of spraints was found on the bank upwind of the stream, whereas remains of frogs eaten by the otters were found on either bank, showing that otters used both banks equally, but wind-direction was a factor in selection of one bank for scent marks.
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Prey Preference of the North American River Otter (Lontra canadensis) evaluated based on Optimal Foraging Theory
Pages 15 - 29 (Article)
Leslie Thompson and Lei Lani Stelle
Prey preference of the North American river otter (Lontra canadensis) was studied in a captive population and evaluated according to optimal foraging theory. Live sunfish (Lepomis spp.), brown trout (Salmo trutta), and crayfish (Cambaridae spp.) were released in a pool, and the search, chase, and handling/eating times of two otters were recorded. When provided with choice of sizes, otters showed a significant preference for catching and eating large prey first. When given a choice of species, otters significantly preferred to catch and eat brown trout first; this preference remained when offered dead prey. Using the rate of energy intake, the preference for brown trout was expected as it provided significantly more energy per unit time, but size preferences only fit predictions after metabolic rate was incorporated, as an otter expends more energy chasing prey in the water than when eating on land. The net energy gained was significantly greatest for large prey in all the size trials and for brown trout in the species trials.  Captive river otters exhibit prey preferences that match our predictions based on optimal foraging theory, which can provide insight into dietary habits of wild otter populations.
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Otters in the Mong La Wildlife Market, with a First Record of Hairy-Nosed Otter Lutra sumatrana in Trade in Myanmar
Pages 31 - 34 (Short Note)
Chris R. Shepherd and Vincent Nijman
Hunting and trade of otters in South-East Asia is a severe threat to the regional conservation of all four species. During surveys of the wildlife trade in the town of Mong La, Shan State, Myanmar, three species of otters were observed, including a skin of a Hairy-nosed Otter Lutra sumatrana. This is the first record of this species in trade in Myanmar, and the second record of the species in the country.
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Reproduction of Reintroduced North American River Otter (Lontra canadensis) confirmed in New Mexico
Pages 35 - 39 (Short Note)
Rowan L. Converse, Melina Baron-Deutsch, Aaron Gjuillin and Abram J. Rowe
The North American river otter (Lontra canadensis) was considered to have been extirpated from New Mexico during the second half of the twentieth century. From 2008-2010, the species was reintroduced to the state; since then, there has been no formal study to evaluate the success of the new population. We conducted informal surveys in 2012-2013 in northern New Mexico in an attempt to ascertain basic demographics of the reintroduced population. We observed four otters, an adult and three juveniles, on two occasions during the summer of 2013 on the Rio Grande in Orilla Verde Recreation Area (Taos County). We photographed the adult and one juvenile on one of these occasions. This represents the first confirmed evidence of river otter reproduction since their reintroduction to the state. Additional research will be required to clarify range extents, dietary habits, ecosystem impacts, and other information important to local wildlife managers.
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A Review of Historical Habitat and Threats to Small-Clawed Otters on Java
Pages 40 - 43 (Short Note)
Erik Meijaard
A review of some new sources of historic information confirm that the Oriental Small-clawed Otter Aonyx cinerea uses a range of non-forest habitats on the Indonesian island of Java. Persecution for its habits to feed in fish ponds is a major threat to this species, and this should be considered when developing conservation strategies for reversing its declines.
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Temporal Detection Patterns of the African Clawless Otter Aonyx capensis (Schinz, 1821) in the Laikipia Plateau of Central Kenya
Pages 44 - 48 (Short Note)
Chege H. Njoroge, Mordecai O. Ogada and Nathan N. Gichuki
The detection time of the African clawless Otter along its habitat was studied from January 2013- April 2013 over 720 trap nights. Camera traps were set up in six sites of different altitudes along the riparian area of the Ewaso Nyiro River in Central Kenya. Based on the still pictures and the time recorded in the snapshot: 50.68% of their occurrence was found to be between 18h00 and 00h00 in the evening, 41.78% between 00h00 and 06h00 in the morning and an insignificant 7.53% between 06h00 and 18h00 during the day. This evidence suggests a temporal detection niche for the African clawless Otter in this ecosystem, which is empirical verification in line with its known cryptic and nocturnal behavior.
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Presence of Giant Otters (Pteronura brasiliensis) in the Río Torno in Northern Peru
Pages 49 - 54 (Short Note)
Ilka Tramm
Listed as endangered by the IUCN Red List the importance of monitoring and assessing viable populations of Giant Otters (Pteronura brasiliensis) is at its top. A small area near the river Tapiche in the northeast of Peru was investigated for the occurrence of Giant Otters. Local people supported the project as field assistants. Otters were seen on 13 occasions and 8 individuals could be identified by their individual throat pattern and the locations of dens were marked in a map. This study confirms the occurrence of giant otters in the Torno area and highlights the importance of conservation efforts in this area.
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