November/December 2002
The Scan of the Wild
by Fred Bank
As
development and urban expansion increase in many areas around the
globe, the transportation systems built to serve this growth can adversely
affect existing wildlife populations and the natural habitats they
occupy. Increasingly, transportation agencies must address impacts
to wildlife and habitat resources when planning and implementing transportation
improvements.
Since the issues involved in addressing these impacts are international
in nature, the Federal Highway Administration's (FHWA) Offices
of International Programs and Natural Environment, the American Association
of State Highway and Transportation Officials (AASHTO), and the National
Cooperative Highway Research Program (NCHRP) recently sponsored an
international technology scan to learn what actions are being taken
abroad to address transportation and wildlife issues.
These organizations chose to examine activities in five European
countries that have successful programs for dealing with transportation
and wildlife issues. Specifically, the scan objectives were to observe
and document policies, technologies, and practices in Europe that
are:
- Reducing wildlife mortality
- Maintaining wildlife habitat connectivity across transportation
facilities
- Protecting threatened populations of wildlife species
- Improving highway safety by reducing collisions with wildlife
In October 2001, an interdisciplinary delegation of Federal, State,
and conservation group representatives visited Slovenia, Switzerland,
Germany, France, and the Netherlands. Although each country uses different
approaches to address wildlife issues, they have formed an international
network to share information. The Infra Eco Network Europe (IENE)
brings together state-of-the-art information on wildlife and transportation.
Through comprehensive research on wildlife and habitat-related issues,
IENE ultimately will benefit all of Europe as well as the rest of
the world.
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A Swiss scientist
sets up an infrared video camera on a overpass to monitor wildlife.
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Slovenia
Slovenia is a young country, a fact that is reflected in the number
and type of actions that it has undertaken to address habitat fragmentation
by highways. Because of the connectivity of its forests with those
of Croatia and Italy, Slovenia has the opportunity to affect the future
of European wildlife significantly.
Although the Slovenians have the necessary environmental laws and
documentation processes to address wildlife-transportation issues,
various environmental issues remain unresolved. The Eurasian brown
bear, for example, is both a protected and a legally hunted species.
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An infrared still
camera with a protective case is mounted on a Slovenian bridge.
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As was the case in several of the European countries visited, hunting
is an important factor in wildlife management. University and forestry
personnel studying wildlife behavior (the Eurasian brown bear in particular)
use information from hunters in their research. They also use public
opinion to influence the transportation ministry to provide connectivity
across highways. The survey indicated the Slovenian public's desire
to accommodate habitat and wildlife considerations.
In concert with public action, the researchers also provide the transportation
agency with specific information on habitat connectivity needs on
Slovenian highways. One result was a viaduct that was constructed
for multiple purposes—habitat connectivity, hydrology, and
human access. Subsequent studies of the structure have indicated that
a variety of wildlife cross under the structure.
Fencing, including electrical fence, is used on Slovenian highways
to keep wildlife off the roads, thereby increasing motorists' safety.
The scan team believes that the situation in Slovenia is similar to
that in the United States because the impact of transportation on
wildlife is an emerging issue, and it often takes diverse interests
joining together to influence the actions of transportation agencies.
Switzerland
In contrast to Slovenia, Switzerland's transportation and environmental
programs have a long history of research and actions related to wildlife.
Swiss actions are scientifically based, supplemented by hunter information
as in Slovenia. Swiss scientists have completed geographic information
system- (GIS-) based identification of wildlife habitat and corridors
nationwide, pinpointing bottlenecks and voids in connectivity. They
characterize the wildlife corridors as impacted, impaired, or interrupted,
with only one-third categorized as intact. The main corridors are
forested, and riparian corridors are highly impacted.
Landscape planning plays an important role in Switzerland, as do
habitat restoration and purchases for connectivity. Expert groups
use scientific research to develop standards for assessing habitat,
as well as designing and implementing restoration and other mitigation
actions. In this process, the Swiss use scientific information from
other European countries extensively, including adopting measures
employed by their neighbors.
The Swiss use a variety of structural and nonstructural measures.
Vegetated overpasses, called "green bridges" or "ecoducts," are a
preferred structure for maintaining habitat connectivity. Swiss research
demonstrates that the diverse habitats on green bridges provide important
connectivity for a broad spectrum of species—from invertebrates
to ungulates. "We compared observations of butterflies crossing highways
between forest segments connected by a green bridge with segments
having no overpass," Verena Keller of the Swiss Ornithological Institute
told the scan team. "Few crossed without, many crossed with the overpass."
Many of the overpasses are multiple use, accommodating forestry roads
and wildlife. The structures are monitored using standard approaches
such as animal tracks and photography, and evolving technologies including
infrared video. The video makes it possible to record the behavior
of the animals while using the structures. The Swiss research indicates
that overpasses with a width of 50 meters (164 feet) or greater are
used by the widest variety of species, and the animals exhibit natural
behavioral characteristics when using the structures.
Germany
German transportation projects identified at the cabinet and parliament
levels are sent to the transportation ministry for implementation.
The Federal Environment Ministry is consulted and enforces environmental
actions using Germany's Nature Conservation Act and what is known
as the "Red List" (threatened and endangered species). All actions
must follow strict measures for using land in a sustainable manner.
Germany has an early warning system of environmental risk assessment
to help avoid environmentally sensitive projects.
Landscape planning plays an important role in identifying protected
flora and fauna and mitigating impacts to the natural environment.
The scan team observed that the Germans apply landscape ecology principles
to highway planning in areas where adjacent land use and distribution
can be expected to change because of highway development. All proposed
detrimental changes to natural areas require compensation measures.
Three kinds of compensation are possible: in-kind, off-site, and compensation
fees (in-lieu-fees), in that order of preference.
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This German highway
features a culvert for habitat connectivity, with a rail barrier
for amphibians and a fence for larger wildlife. |
Legal requirements in Germany necessitate wildlife fencing (needed
because many highway stretches have no speed limits), signing, underpasses,
green bridges, and land conservation as mitigation for transportation
facilities. Germany has the largest number of green bridges (32) of
the countries visited. The overpasses vary in width from 8.5 to 870
meters (27.9 to 2,854 feet). Eight more are under construction, and
another 20 are planned. Forest and agricultural roads cross about
half of Germany's green bridges. In other cases, large rocks are used
to keep vehicles out of wildlife underpasses and off overpasses.
The team observed extensive projects to keep amphibians and other
small animals away from roads by constructing fences and crossing
structures. More than 100 such projects for small animals were completed
nationwide. The Germans also report that 130 bridges over rivers were
designed to accommodate wildlife passage and keep the animals away
from the traffic lanes.
"Where do the bats fly? Where do the birds cross?" said an unidentified
member of the German team hosting the scan tour. "We consider even
these small details when deciding where to construct a green bridge."
France
France's transportation plan is derived from a land-use plan whose
goal is to have all residents live within 5 kilometers (3.1 miles)
or 45 minutes from a limited-access highway or high-speed rail. Using
the French Law of Protection of Nature as guidance, both the environmental
and the transportation ministries must approve highway projects. No
separate permits are needed for the various aspects of a project—one
approval does it all. An extensive public involvement process is used,
and legal challenge is frequent. Many projects can take as long as
10 years to develop. Environmental factors receive equal consideration
with social and economic factors.
The French transportation ministry's primary objective when looking
at transportation and wildlife issues is to increase motorist safety.
Approximately 30 deaths per year result from collisions with animals.
"Unfortunately, we drive too fast," said Michel Galet of Cofiroute,
the French tollroad company. "We must consider safety as a major reason
for measures to keep animals off our highways."
The French have taken numerous measures to reduce wildlife collisions.
Fencing for wildlife is required on all federal highways. The French
reported to the scan team that permanent signing does little to reduce
wildlife mortality, and measures such as reflectors and vehicle-mounted
whistles generally are ineffective. Culverts, underpasses, overpasses,
and viaducts are used as structural alternatives.
Wildlife Connectivity Scan Team Members
- Fred G. Banks, FHWA Coleader, FHWA, Headquarters
- C. Leroy Irwin, AASHTO Coleader, Florida Department of
Transportation (DOT)
- Gary L. Evink, Ecologist, Scan Facilitator
- Mary E. Gray, FHWA, Washington Division
- Susan Hagood, The Humane Society of the United States
- John R. Kinar, P.E. Wisconsin DOT
- Alex Levy, FHWA, Southern Resource Center
- Dale Paulson, HWA, Montana Division
- Bill Ruediger, U.S. Forest Service
- Raymond M. Sauvajot, Ph.D., National Park Service
- David J. Scott, PE, State of Vermont Agency of Transportation
- Patricia White, Defenders of Wildlife
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France was the first European country to construct green bridges
for wildlife and has an extensive network of such structures. The
widest is 800 meters (2,624 feet). France also was the first European
country to try the hourglass-shaped green bridge to reduce structural
cost. The size of these bridges varies at the narrowest point from
8 to 15 meters wide (26 to 49 feet). The French have tried a number
of designs for amphibian crossings, including a directional trench
to guide the animals to one-way pipes that cross under the highway.
They use plastic mesh attached to the regular wildlife fence to guide
amphibians to culverts.
Structures generally are monitored for a 1-year period and then revisited
3 to 5 years later. The monitoring information is used in future projects
and guidance documents.
The Netherlands
The Netherlands is a leader in the European community on wildlife
and transportation issues, despite the fact that the country has very
little remaining habitat for wildlife. The Dutch have a strong philosophy
of providing and improving habitat connectivity across the highway
system. The country has a national habitat connectivity plan that
is consulted when planning for improvements to the transportation
system, as well as individual projects. On existing highways, maintenance
crews refer to the plan when implementing retrofit projects to enhance
habitat connections and protect species.
The plan uses viability analyses at the population level and information
about locations of elevated wildlife mortality from collisions (individual
level). Because loss of population viability is in many cases exclusively
the result of road presence (a barrier), both policymakers and managers
give high priority to restoring habitat connectivity across highways.
"You can't do everything at once, but you can do something with each
project," said Hans Bekker, program manager for defragmentation at
the Netherlands Ministry of Transport.
The Dutch take extensive and innovative measures to protect some
species. The most extensive measures are for badgers, the largest
carnivore in the country. Many initiatives to save the badger result
from cooperation between nongovernmental organizations (NGOs) and
the Dutch environmental and transportation ministries. In fact, the
transportation ministry made badger protection a national priority.
An extensive system of approximately 600 culverts is provided for
connecting badger habitats, and highway maintenance funds are used
for retrofits, which are based on a system-wide transportation plan
for the entire country.
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A fence near a Dutch
overpass includes a one-way door for small mammals. |
In addition to measures for badgers, the Netherlands has 10 pipe-culvert
systems designed specifically for amphibians and strategically located
to provide for seasonal movements. Existing bridges and culverts for
waterways were modified to provide dry passage on wooden or earthen
shelves along the insides of the structures, primarily for small-mammal
movement. Other measures for small animals include tree stumps placed
on or under bridge structures to provide habitat for cover and passage
across or under highway facilities.
The Dutch have constructed four ecoducts, as green bridges are called
in the Netherlands. The ecoducts range from 17 to 50 meters (56 to
164 feet) wide, using either the hourglass-shape or straight-side
design. All have fences and earthen berms along the edges for noise
and light reduction.
Recommendations
The scan team developed recommendations in four topic areas: policy,
communications, guidance manuals, and research. Concerning policy,
the team believes that the FHWA and AASHTO strategic plans should
contain objectives to address wildlife mortality and habitat connectivity
issues.
They also believe that a policy of ecosystem-level mitigation should
be implemented. Another policy should ensure consistency of highway
alignments and designs with the management objectives of adjacent
public lands. Post-construction monitoring and maintenance of measures
implemented for wildlife are essential as well.
Regarding communications, a central source of information on wildlife
and transportation is important, including provisions for international
exchange. The scan team believes that the publications produced by
various wildlife societies and groups should be used to disperse wildlife
and transportation information. Similarly, the universities and State
wildlife agencies that conduct much of the wildlife research should
disseminate information, and the streamlining and stewardship programs
in the State transportation agencies should do so as well.
The scan team has identified a number of guidance manuals that could
be developed, including a general one on the assessment of transportation
impacts on wildlife. Guidance on coordination with resource agencies
and nongovernmental organizations could be a component of that publication.
A glossary of definitions of commonly used terms in the wildlife sciences
and transportation should be developed, as well as a design manual
for wildlife structures, in coordination with FHWA and AASHTO.
Finally, the team recommends interagency efforts to study connectivity
needs for all types of wildlife in the United States, possibly including
a connectivity study relating to the Nation's transportation system.
Interagency cross-training would be desirable.
The Transportation Research Board (TRB) and AASHTO Standing Committee
on the Environment could take leadership roles in implementing all
of these recommendations.
Author's note: This article was excerpted from the scan team's
final report, Wildlife Habitat Connectivity Across European Highways
(FHWA-PL-02-011). The contents reflect the view of the authors and
do not necessarily reflect the official policy of the U.S. Department
of Transportation. The report summary is currently available on the
Web at www.international.fhwa.dot.gov.
The full report will be available at the same address in the near
future. Hard copies are available free of charge by contacting the
FHWA Office of International Programs: international@fhwa.dot.gov
or 202-366-2155.
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The habitat overpass
includes board fences to reduce road noise and lights. Rocks are
placed at the ends of the overpass to prevent vehicular use. |