IN A last-ditch attempt to save the European mink from extinction, biologists
in Britain and Estonia are attempting to establish a breeding population on an
island in the Baltic Sea.
David Macdonald of the University of Oxford outlined the European mink鈥檚
plight at a symposium on carnivore conservation at London Zoo last month.
Competition with introduced American mink has made the species Europe鈥檚 most
endangered mammal.
Over most of its former range, the European mink (Mustela lutreola)
has been replaced by the American species (M. vison), which was
introduced in the 1920s because of its superior fur. The European mink survives
in the former Soviet Union, northern Spain and southwest France. But the total
population has been reduced to just a few hundred individuals. 鈥淚t is certainly
heading for extinction,鈥� says Macdonald.
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Working with biologists in Belarus, Macdonald and his colleagues have studied
the interactions between the two mink species in the northeast of the republic,
close to the Russian border. American mink only expanded into this area about 15
years ago.
The scientists had thought that the alien intruders would either compete with
the native species for limited food or that males would oust their smaller
European cousins in competition for mates, diluting the pure European stock by
interbreeding. However, field studies showed that food is not the problem. The
American mink take a wider range of prey, but frogs鈥攖he main food of the
European mink鈥攁re never in short supply. Nor is there any evidence of
matings between species.
Instead, the intruders use their greater size and ferocity to chase European
mink away from the best hunting grounds. 鈥淎merican mink of both sexes will
actively seek out and attack European mink and drive them out of the area and
into suboptimal habitats,鈥� says Macdonald. 鈥淭hey are enthusiastic about kicking
the stuffing out of the native mink.鈥�
This competition has had a startling effect on the remaining populations of
European mink in Macdonald鈥檚 study area. Over a space of a few generations their
average size has increased by between 12 and 15 per cent, so that the two
species are now almost the same size. 鈥淥nly the biggest have any hope of
withstanding the onslaught of the American mink and so these are the only ones
that have survived,鈥� Macdonald explains.
But even this exercise in accelerated evolution is unlikely to save the
European mink. 鈥淚 doubt that the larger European mink are a match weight for
weight,鈥� says Macdonald. 鈥淭he American species is more aggressive and can
intimidate other individuals of its own size.鈥�
The only conservation options, he says, are to establish viable populations
on islands in the Baltic, or to employ trappers to catch both species, killing
the intruders and releasing the European mink.
Macdonald鈥檚 team is now attempting to wipe out a population of American mink
on the Estonian island of Hiiumaa, which has an area of some 1000 square
kilometres. The three-year project, funded by Britain鈥檚 Darwin Initiative, a
scheme to promote biodiversity, aims to replace the American mink with European
mink from a breeding population of 80 animals, currently held at the Tallinn
Zoo.