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Volume 1 Pages 1 - 23 (May 1986)
Citation: Chehebar, C. (1986) The Huillin in
Argentina. IUCN Otter Spec. Group Bull. 1: 17 - 19
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The Huillin in Argentina
Claudio Chehebar
Administracion de Parques Nacionales, Santa Fe 690..
1059 Buenos Aires, Argentina.
In lakes, ponds and rivers in the Argentinean Andes of Patagonia, in
central and southern Chile, and in the complex, fjord-rich marine
coasts of southern Chile and its islands, lives the species of otter
which seems to occupy the smallest geographical range (in terms of area)
in the world: the southern river otter or huillin, Lutra provocax
.
In 1982 we began research in Argentina on this previously almost unknown
species, which is included in the IUCN Red Data Book as "Indeterminate",
and is included in the Argentine list of endangered species. The work,
financed by the National Parks Administration, covers several aspects
of huillin's conservation biology.
- Distribution survey:
As with much of the South-American fauna, the published geographical
range of this species, particularly in Argentina, was vague, so in
fact we did not know where the populations actually were. We
adapted to our conditions the methodology of the British surveys for
the Eurasian otter, and visited 275 sites in the north-Andean
Patagonic National Parks (Lanin, Nahuel Huapi, Puelo and Los Alerces),
in search of huillin signs. We found evidence of the otter's
presence at only 32 sites (11.6%), most of them (28) in the large
Nahuel Huapi Lake sub-basin. These Andean parks are mountainous,
with many lakes of glacial origin, and densely forested, with a cool
climate.
The species, according to local settlers and Park-rangers,
disappeared from the other 3 parks and from the south of Nahuel
Huapi in the last three or four decades, apparently due to intensive
hunting. The population of Nahuel Huapi is of critical importance
for conservation of the species in Argentina. There is also a
population on Staten Island (Tierra del Fuego) but its importance
and status is, as yet, unknown.
The results of the survey also indicate that human disturbance by
itself (of course, if animals are not hunted) has not had a
significant impact on huillin populations and status. We measured
the effect of frequency of human visitors, presence of settlements
nearby and the presence of domestic dogs, for each site. The results
also strongly suggest that very dense and mature vegetation cover on
the shore, very close to the water's edge, including abundant fallen
trees, is a key factor for permanent and healthy populations. (For
details see Chehebar 1985, 1986).
- Food-habits and habitat use:
We decided to make studies on some aspects of the ecology of the
species in Quetrihue Peninsula, Nahuel Huapi Lake, especially in
Laguna Patagua. Otters use this pond all the year round, with
roughly the same intensity at all seasons, judging from scat
deposition rates. Through analysis of scats on a monthly basis, over
18 months, we now know that there, the huillin feeds mainly on
macrocrustaceans - the anomuran Aegla, endemic to South
America, and the parastacid crayfish Sammastacus. Fish make
up a very low percentage of the diet, with a peak of 10% (frequency
of occurrence) during late autumn. Otters also seem to eat large
quantities of clams (Diplodon) but we have not directly
confirmed this yet. The most likely explanation of this pattern,
i.e. few fish and many crustaceans, lies in the relative
availability and abundance of prey species in these oligotrophic,
clear and cool waters.
We have also mapped scat distribution, to gain insight into habitat
use, and the data are being analysed.
- Behaviour:
We have begun the last phase of the study, using radio-tracking (the
equipment has been bought with OSG funds). We hope to obtain
information about movements, home range, habitat use, activity
patterns and, with a little bit of luck, densities. The ultimate
goal is to devise a management strategy.
We recommend re-introduction of huillines in Lanin, Puelo and Los
Alerces National Parks, through translocations of animals, so as to
minimize the risks involved in the present dependence on Nahuel Huapi
and Staten Island (as far as we know) for the conservation of the
species in Argentina. Also, we recommend careful monitoring and
protection of the Nahuel Huapi population and protection of the Staten
Island ecosystems.
The work benefited from the participation of Maria D. Gottelli,
Adriana Gallur, Guillermo Giannico, Pablo Yorio, Patricia Livingston,
Javier Perez Calvo, Graciela Artigas and Alcides Iacopini.
References
Chehebar, C. 1985. A survey of the
southern river otter Lutra provocax Thomas, in Nahuel Huapi
National Park, Argentina. Biol. Conserv. 32 (1985)
299-307.
Chehebar, C., Gallur,
A., Gottelli, M., Giannico, G. and Yorio, P. 1986. A survey of the southern river otter in
Lanin, Puelo and Los Alerces National Parks, Argentina, and evaluation
of its conservation status. Biol. Conserv. (In press).
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