Tuesday August 9, 2011
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Severtev Institute, Russian Academy of Sciences, 33 Leninsky Prospect,
Moscow Y-71, Russia
The otter, which inhabits Indochina belongs to the form Lutra lutra barang F. Cuvier, 1823 (Heptner et al, 1967). Very little is known about the ecology and biology of this otter form (Pierce et al, 1990; Foster-Turley el at.. 1990). Thus our data about this otter form collected in South Vietnam are of certain interest.
The study was carried at two localities in the northern part of the Thainguen Plateau in Zalai Province (formerly Zalai-Kontum) in December of 1989 and January of 1990. The first locality is in the upper reaches of the Ba and Kon rivers, approximately 75 km north of Ankhe city and is in the primary tropical forest, 900 m ASL. The second locality is situated more to the south. It is in the suburbs of Buon Lyoi, 50 km north of Ankhe city and also belongs to the high primary tropical forest, 600 to 700 m ASL. Both areas have low human population density.
In total 45 segments of riverbank, each 1000 m long, were searched for the signs of otters. The greatest area searched lay along the Thia and Buon Lyoi rivers and their tributaries. The spraints on the sand bars, stones and logs in the stream as well as other otter signs were mapped. On the sand bars otters scraped up sand into small mounds and defecated on top. In the faecal deposits there were commonly 1-8 spraints. In some cases higher numbers of spraints were found. It is interesting to note that on stones, logs and sandy bars with otter spraints, there were no faeces of other mustelids, viverrids or other tropical carnivorous animals which mark their territory. If the substratum was suitable, other traces should have been found too.
Otter spraints were dried, broken and analysed. Five prey classes were present in the diet of otters of Thainguen Plateau: fish (14-85 %), amphibians (9,5-57 %), crabs (3,8-54,2 %); water insects and snails were of minor importance in the diet (0,8-8,0 %). Considerably greater densities of spraints were found in the junctions of rivers and their tributaries. On the Thainguen Plateau traditional places (sprainting sites) were used for scent marking. Such sprainting sites occurred most frequently at the intervals of 2 to 10m, sometimes, 200 to 300 m. Intervals of 200-300 m without sprainting sites most probably do not disrupt the information necessary to moving otters. The sprainting sites were found mostly on stones (49.2 %) and logs (28,6 %). We want to stress that in woody areas sprainting sites of otters were mostly found in the river, whereas in open areas - on river banks. In woody areas otters have presumably more dangers, thus they choose stones and logs in the river as the places for sprainting. Our data show that the otter moves about 3 km per day and makes periodical movements from one site to another within its home range. In places of plenty of food and holts they can stay for some days. After 15-20 or more days otters again cover the same route within their home range.
Foster-Turley, P., Macdonald, S., &
Mason, C. (Eds) (1990). Otters. An action plan for their
conservation. 126pp. IUCN, Gland, Switzerland.
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