130925-studie-wildlife-comeback-in-europe

Figure 1a.
Distribution of
Wolverine in Europe
in 1850 [1] , 1955 [31] and
2009–12 [2, 18] . Please
note that the map
for 1850 is based on
bounty statistics
compiled at the
county level,
which results in an
overestimation of the
occupied range [19] .
The map for 2009–12
includes areas of
sporadic occurrence
as well as confirmed
reproduction [18] .
is presumed to have been overestimated, with
some suggesting that it is, in fact, smaller than
the combined numbers in Norway, Sweden and
Finland [25] . Wolverines in European Russia are
believed to be declining [1, 12] due to low reindeer
density [11] , high human density [11] and high levels
of poaching [26] .
The second largest population by country
can be found in Sweden. Following increases
and expansions [27, 28] , two new populations that
were confirmed in the centre of the country in
the 1990s [29] have now been incorporated into
the species’ range, thus creating a continuous
population across Sweden and Norway [27, 28] . The
Wolverine is more widely distributed in northern
Sweden although densities vary at a local level [27] ,
and the species is continuing to spread southand
eastwards [28] . Wolverines are protected under
Swedish law, but the overlap with reindeer herding
areas [27] and resulting depredation causes conflict,
which is a common problem throughout much of
their northern European range [1, 4, 29] .
Abundance and distribution: changes
Like many other large carnivores, the Wolverine
has experienced a pronounced reduction in
range since historical times. Once widespread
across most of Scandinavia and Eastern Europe,
the species lost over 60% of its territory between
1850 and 1955 (mainly from the south), leaving it
confined to the northern parts of its historical
distribution (Figure 1a). During this period,
it retreated to uninhabited and remote areas
especially mountainous regions in Scandinavia,
which remained a stronghold for the species [1, 27, 29] . It
should be noted, however, that differences in map
resolution between the 19 th and 20 th century, caused
by differences in data collection methodology
and mapping accuracy, are likely to lead to overor
underestimations in range change over time.
Because the 1850 distribution is based on bounty
statistics at the county-level, it is reasonable to
assume that the species’ actual range was smaller
than depicted [19] , which would, in turn, lead to a
smaller contraction by 1955. Similarly, the subsequent
expansion from mountainous refuges into
forested landscape [19] at the Wolverine’s southern
limit in Sweden and Finland (Figures 1a and b), which
primarily occurred in the 21 st century (not shown),
was perhaps more pronounced than depicted.
This is because the 1955 map is based on reports
and assumptions, while the present distribution
resulted from a modern, large-scale monitoring
programme [19] . It is therefore possible that the
contractions observed in some areas, particularly
in southern Russia (Figure 1b), are an artefact of
the difference in the types of measurements that
are being compared. In addition, the expansions in
southern Norway may not reflect reality because
the present day range information comprises areas
of sporadic occurrence where the species is heavily
culled, which in turn has a profoundly negative
effect on reproductive success [30] . According to
the perhaps biased estimates presented here, the
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