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Population ecology of free-ranging American mink Mustela vison in Denmark
PhD thesis
By Mette Hammershøj
Abstract
This PhD thesis presents the results of various studies of free-ranging American
mink Mustela vison in Denmark. Stable carbon isotope analyses of teeth and claws
from 213 free-ranging mink from two areas in Denmark showed that nearly 80%
were escaped farm mink. A genetic analysis of a sub-sample of the same animals by
means of microsatellites corroborated this result. The isotope analyses permitted the
separation of the mink into three groups; newly escaped mink, 'earlier' escaped mink
(having lived in nature for more than ca. two months), and wild mink. The survival
of these three groups differed. Once an escaped farm mink had managed to stay alive
in nature for more than two months, its chances of survival were as good as for the
wild mink. Mink diet consisted primarily of mammals, followed by amphibians,
birds and fish. Diet of polecats from the same area is also described. Finally, the thesis
gives results from model simulations (including evolution) of the possible effects
on the free-ranging population of reducing the number of escapes or completely
closing down fur farms in Denmark.
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