130925-studie-wildlife-comeback-in-europe

Red deer at the
Oostvaardersplassen
nature reserve in The
Netherlands. Deer
densities here are
almost 1 deer per 2
hectares of land. That
is higher than in the
Serengeti.
tives (e.g. conservation payments) [31] . Land/water
protection and Land/water management were
combined for the purpose of mammal species
accounts, based on the IUCN Red List guidelines
for describing conservation actions in place [33] .
In addition, information was included on the
pan-European legislation for each species (see
Table 1).
Preparation of species accounts
The information on population and distribution
trends, threats, conservation actions and reasons
for recovery was compiled into individual species
accounts. Each species account was reviewed by
at least one species expert, in order to ensure the
accuracy of the abundance and distribution data
presented, as well as that of the threats and conservation
actions identified and their interpretation.
Data analysis
Distribution
The area occupied was calculated at each time
point (historical, past, and present) to examine
changes in the range area for each species except
colonial nesting bird species, for which individual
colonies were mapped rather than distribution. As
the majority of information on the distribution
of bird species derives from atlas data, changes
in range area were also calculated on the basis of
a 50 km x 50 km grid, in order to better capture
the changes in area of distribution of species with
small ranges in particular.
Species varied in terms of the precise date for
which historical range extents could be reconstructed.
For many species, dated information was
available, although for some species [e.g. European
bison (Bison bonasus), Red deer (Cervus elaphus)
and Iberian lynx (Lynx pardinus)], ranges were
mapped based on data from an imprecisely dated
time point in history (e.g. Pleistocene, pre-1900,
1800s). We aimed to map distributions for those
dates closest to 1850 and no later than 1900.
Recent range changes
We produced species richness maps for past and
present distributions of our study species. For
this, we overlaid a hexagonal grid onto the aggregated
species’ distribution. The grid is defined
on an icosahedron, projected to the sphere using
the inverse Icosahedral Snyder Equal Area (ISEA)
projection. We then summed the number of
species occurring in each hexagonal grid cell (cell
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