Scientists from NERI,
Aarhus University, have shown that roe deer
and red foxes as well as several small mammals
use the constructed wildlife
overpasses across route 18 Herning in Jutland.
However, the scientists also give advice
to how wildlife overpasses might be improved.
Large infrastructures
like roads have direct and indirect impact
on wildlife. Roads may restrict the animals’
dispersal and habitat use. To reduce the
fragmentation of the landscape, fauna passages
are constructed to allow the wildlife and
other fauna a safe dispersal route across
the road barrier. Experimental studies of
the efficiency of large fauna passages have
not been performed. Monitoring of the animals’
use of fauna passages are needed to optimise
the design of new fauna passages.
Monitoring of the use
of the three wildlife overpasses at Herning
by mammals showed that roe deer and red
fox crossed the overpasses most regularly.
Brown hare, badger and medium-sized mustelids
only crossed the overpasses occasionally.
Among the small mammal species yellow-necked
mouse, harvest mouse and common shrew were
recorded most often. Pygmy shrew, bank vole,
field vole, common vole, wood mouse were
recorded in low numbers. Some of the yellow-necked
mice and a bank vole crossed the overpasses
during the study. Daubenton’s bat, serotine,
Nathusius' pipistrelle, noctule and parti-coloured
bat were detected, but the activity of bats
was generally low in the area. It was not
possible to conclude whether the bats cross
the road along the overpasses.
The three wildlife overpasses
near Herning and older Danish wildlife overpasses
are all too narrow to function as efficient
fauna passages for a broad range of species.
Furthermore, to mitigate the barrier effect
of roads for mammals efficiently the distance
between suitable fauna passages must be
smaller than presently practiced in Denmark.
Based on the results from the Danish and
other European studies NERI recommends the
following guidelines for new wildlife overpasses
in Denmark:
Wildlife overpasses designed to meet the
need for several species should have a minimum
width of 50 m.
Smaller overpasses designed to meet the
specific needs of single smaller species
should have a minimum width of 20 m.
Wildlife overpasses for more species with
different habitat use, e.g. mammals, reptiles,
and amphibians, should have a minimum width
of 80 m.
The openness index should be minimum 0.8.
Preferably it should be larger than 1.0.
Combined use of overpasses as fauna and
human passages is not recommended.
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The National Environmental
Research Institute has been closed. New
national centre now in operation
The National Environmental
Research Institute (NERI), Aarhus University,
has been closed, and the research-based
consultancy services to authorities on nature,
environment and energy are now – as per
1 July 2011 – provided by the National Centre
for Environment and Energy (NERI), Aarhus
University.
The National Centre
for Environment and Energy (NERI) is the
portal for authorities, businesses, interest
organisations and the public to the strong
expertise of Aarhus University within nature,
environment and energy.
Kurt Nielsen, vice-dean
for knowledge exchange at the Faculty of
Science and Technology, Aarhus University,
is director of the National Centre for Environment
and Energy (NERI).
The research departments
of the closed National Environmental Research
Institute are now affiliated to the Department
of Bioscience and the Department of Environmental
Science.
In the future, the National
Centre for Environment and Energy (NERI)
can in its research-based consulting and
knowledge exchange benefit from the university’s
comprehensive research expertise.
The National Centre
for Environment and Energy maintains NERI
as an integrated part of its name.
The Centre’s website
is currently under construction at the address
www.dmu.au.dk. For a transitional period
the National Environmental Research Institute’s
former website will be available via the
Centre’s homepage.
Continuation of information
Using existing subscription
lists, the National Centre for Environment
and Energy (NERI) will continue to inform
the media and other interested parties of
new research reports and other current research
topics under study at Aarhus University
within the fields of nature, environment
and energy.
