Vladivostok
CONSERVATIONISTS have overestimated the number of endangered Siberian
tigers by a factor of two, according to Russian scientists who have pioneered a
method that uses sniffer dogs to count the animals.
Last year, a survey backed by the World Wide Fund for Nature (WWF) estimated
that there were between 415 and 475 animals living in Russia鈥檚 far east, between
the Amur River and the Pacific coast
(This Week, 30 November 1996, p 5). This
was twice the number counted in previous surveys and raised hopes that the tiger
was winning its battle against extinction.
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But wildlife scientists working in the Lazovsky State Nature Reserve in
Russia鈥檚 Primorsky Krai region now claim that the earlier, more pessimistic
figures are nearer the mark. 鈥淚t鈥檚 a question of methods,鈥� says Sergei Shaitarov
of the Tiger Protection Society in Vladivostok, which sponsored the new sniffer
dog survey.
鈥淭he WWF estimated the number of tigers by counting their tracks in the
snow,鈥� says Shaitarov. The problem with this approach, he says, is that it is
easy to count the same tiger in different places.
The new technique uses German shepherds that have been trained to
distinguish between the odours of different tigers by rewarding a correct match.
The Lazovsky team trained the dogs to distinguish between the odours of circus
tigers.
Tigers mark their territory with excrement and urine and by scratching trees,
which then carry the scent from glands on their paws. Galina Salkina, the
Lazovsky reserve鈥檚 cat specialist, collected samples of these scents, and by
watching the tigers from hides was able to link specific samples with individual
animals. The samples retained an individual scent that was recognisable to the
dogs for years.
To enumerate the population, the researchers exhaustively collected samples
in the field and brought them back to the lab for the dogs to match to the
stored samples. Dogs encountering an unfamiliar scent are trained to recognise
it in future. 鈥淯sing this method we can count the number of tigers all year
round,鈥� says Salkina.
The survey puts the number of tigers in the Lazovsky reserve at 12, rather
than the 22 estimated by the WWF. Extrapolating these results to the rest of the
tiger鈥檚 range produces a total population of around 250.
Dale Miquelle of the Hornocker Wildlife Research Institute in Moscow,
Idaho, which took part in the WWF study, says he wants to see the technique
replicated elsewhere before accepting the revised figures. 鈥淚t is difficult to
make comparisons across countries, when the counting methods are different,鈥� he
says.