On The Permeability Of
Roads For Wildlife
A Handbook
Authors:
Václav Hlaváč, Agency for Nature Conservation and Landscape Protection of the
Petr Anděl,
Czech Republic
CSc. Evernia s.r.o., Liberec
Technical cooperation: Radomír Bocek - Roads and Highways Directorate of the Czech Republic
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This handbook is based upon the results of a four-year research programme carried out by
Agency for Nature Conservation and Landscape Protection of tthe Czech Republic (AOPK CZ).
The following people were involved in different phases of the research:
Ing. Václav Hlaváč, RNDr. Aleš Toman, Ing. Luděk Čech, Jan Aubus, DiS, Daniel Korábek, Mgr.
Jiří Šafář, RNDr. Jiří Pykal, Ing Jana Kubová, Mgr. Michaela Braunová, Ing. Václav Říš,
Mgr.Vladimír Čeřovský, Mgr. Michal Tomášek, Mgr. Pavel Marhoul, Mgr. Ondřej Volf, Mgr. Eva
Suchomelová, Mgr. Michal Andreas, Mgr. Světlana Vránová, RNDr. Jiří Rejl, Ing. Roman Zajíček,
Ing. Vladimír Vykopal, Mgr. Leoš Šizling, Mgr. Tomáš Matyáštík, Ing. Jaroslav Červený, CSc.,
RNDr. Petr Koubek, CSc.
Ing.arch. Marek (JM Projekt Chotěboř) designed the schemes for ecoducts; Valbek spol. s.r.o. provided
schemes for individual types of passages.
This handbook is approved by Ministery of Environment and its use is
recommended for preparation and permitting of highway constructions in the
Czech Republic
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Table of contents
1. Introduction
Part a – Definition of the problem and available data
2.
3.
4.
5.
Principles and definition of terms
The effect of road networks on nature; habitat fragmentation
Animal migration and behaviour in contact with highways
Summary of research to date
5.1. The use of various bridge types by otters
5.2. The evaluation of the present highway system and high speed road network
from the point of view of facilitating passage for large mammals
5.3. A proposed migration profile handbook for road designers
5.4. A classification of the territory of the Czech Republic with respect to the
diffusion of large mammal species
5.5. Evaluation of the practicality of various types of passages for specific
species of large mammals
6. Affected animal species
7. Classification of roads according to their barrier effect
8. Classification of passages
9. Factors affecting the effectiveness of passages
9.1.
The condition of the animal population
9.2.
The condition of the surrounding area
9.3.
Disturbances
9.4.
Passage dimensions
9.5.
The area under the bridge
10. The migration potential theory
Part b - Recommended optimal approaches and solutions
11. Planning migration passages - the density and location
11.1. National considerations
11.2. Regional considerations
11.3. Local considerations
12. General guidelines for passage construction
12.1. Ecoducts
12.2. Multipurpose overpasses
12.3. Special underpasses
12.4. Multipurpose underpasses
12.5. Culverts
12.6. Specifics of construction of passages in lowlands
12.7. Reduction of noise in the vicinity of all types of passages
13. Accompanying measures
13.1. Fencing
13.2. Crash barriers
13.3. Maintenance of vegetation in the neighbourhood of highways
14. Integration into Czech Ecological Network and land use planning
15. Facilitating passage in specific stages of planning and approval of construction
16. Facilitating passage in other types of line barriers
17. Conclusion
18. Literature
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1. Introduction
Busy overland roads, especially highways, create barriers for migration of wild animals, causing
fragmentation of their habitat and, ultimately, of populations. Isolated populations are unstable and an
increasing density of highway networks is becoming the chief risk factor for the existence of some
species.
The purpose of this handbook is to provide a summary of the current level of knowledge, and to
specify a basic approach to the solution of the problem of migration of wild animals in relationship to
overland roads. The introductory chapters (1 to 10) define basic principles and starting points and
summarise research to date. The second half (Chapters 11-16) concentrates on general
recommendations – especially recommendations that facilitate passage through road sectors and
accessibility of specific migration areas. Recommendations for the design of road construction and
building permit procedures are also included. It is not possible, however, to provide technical details of
these procedures for specific highway design stages in this handbook as these requirements must be
based on detailed research of specific sites. The next phase of this project should involve a manual for
traffic planners providing more details on the technical design of various types of passages.
Part A – Definition of the Problem and Available Data
2. Principles and definition of terms
The barrier effect of highways is one of the crucial problems of animal conservation today.
During the planning of new roads, therefore, as well as during the repair of existing roads, it is
necessary to provide for sufficient free passage of wild animals. The solutions to this problem must
always be based on detailed and current zoological data on species which could be endangered –
from general information on dispersion and numbers of the species, their manner of use of their
habitat, territoriality and migration behaviour, including information on social and spatial structure
of the local population and its motivation to use the passages, to the psychology of the individual,
which often determines the animal’s decision whether to pass under the bridge, run across the
highway, or turn back. The methodology presented is an attempt to generalise these findings and
their translation to the level of technical data suitable for use in road design.
1) The subject of the solution is the conflict between fauna, a biotic component, and a road, an
anthropogenic/technical component. In providing a solution, both components must be considered,
and any specific solution must then be the result of cooperation between biologists and technicians.
2) Animal migration as well as technical road design are both complex systems and every single
passage has its specific problems. The basic principle for creating passages through specific areas
must then be a combination of respecting general principles and individual approaches to each
case in an attempt to respect local conditions as much as possible.
3) Financial investments into migration passages are sensible only where they fulfil their purpose
and, at the same time, the results achieved are commensurate with the cost, i.e. cost-benefit analysis.
4) Animal migration as an expression of a biological system is a very variable issue influenced by a
number of external and internal factors. It is obvious that the evaluation of the effectiveness of a
planned passage must be based on assessment and is only of a stochastic character. In this
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5) methodology, this stochastic character is expressed by the term ‘migration potential’
expressing the potential of a given profile for facilitating migration (for details see Chapter 10).
6) The methodology is designed as an open system, which may update the proposal on an ongoing
basis through professional consultation, literature research, and results of biological research of
existing passages.
Definitions of Selected Terms Used:
•
•
•
•
Passage – a construction facilitating animal migration through a highway. Passages may be
overpasses or underpasses. It is necessary to distinguish between the terms ‘bridge’ and
‘passage’ (not all bridges are suitable for animal migration; other constructions may also
facilitate passage, e.g. tunnels, sluices, special passages for specific groups of animals). There
is also a crucial difference when giving the dimensions of passages (underpasses) and bridges.
In the case of a bridge, the length is the dimension parallel to the axis of the highway and the
width is the dimension perpendicular to the axis of the highway; however, in the case of an
‘underpass’ it is the other way around. The length of an underpass is the distance between the
‘entrances’ and the width is the perpendicular distance between the walls of the underpass
Migration Construction – a synonym of ‘passage’
Migration Profile – the place where a migration route crosses an overland road
Migration Potential – the probable effectiveness of a migration profile (for details see Chapter
10)
3. The effect of road networks on nature; habitat fragmentation
Busy roads (especially highways) have a significant effect on the surrounding natural environment.
One of the most important effects is the fact that, for a number of organisms, they represent impassable
barriers. Other effects include a loss of habitat during road construction, the killing of animals by
passing vehicles, contamination of the environment, and various types of disturbance (noise, etc.). The
indirect influences of roads are also significant, such as an increase in urban pressure in areas not
previously accessible, secondary construction along roads, etc.
The barriers created by roads represent long lines that animals are unable to bypass. Major roads,
therefore, cause habitat fragmentation as well as the fragmentation of the population of resident
species. The increasingly dense highway network then turns the originally open landscape into a
system of isolated ‘islands’. Due to habitat fragmentation, populations are then exposed to the socalled ‘island effect’. Small isolated populations generally find it more difficult to handle natural
fluctuations in numbers caused by climatic changes, natural disasters, epidemics, etc.; an insufficient
genetic diversity may also become apparent in the long-term. At a certain level of density of the
highway network, this becomes a survival problem for some species, especially in cases where a
relatively small number of individuals inhabit an extensive area. Logically, some species of large
mammals will then be among those most endangered. Smaller mammals are usually less affected by
the existence of highways, particularly as populations living in those sections of the landscape defined
by the highway network are usually sufficiently numerous, and the highway effect is therefore less
obvious. Also, smaller mammals usually find sufficient opportunities to cross highways through, for
example, sluice culverts, which cannot be used by large animals. Highways, therefore, present a real
and crucial problem for large mammal populations.
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4. Animal migration and behaviour in contact with highways
In most mammal populations, under normal conditions, there is always a part of the population that
does not maintain permanent home ranges and moves over large distances. These are frequently
adolescent individuals pushed away from their home areas; in other cases, older full-grown individuals
migrate. For many species, the motivation and principles of this migration have not been entirely
clarified as yet, however, it is certain that these migrations are crucial for the survival and well being of
the population. Migrations from prosperous parts of the population make it possible to permanently
populate less suitable habitats, where an isolated population would become extinct within a short time.
Migration makes it possible to compensate for fluctuations in numbers caused by a temporary
worsening of habitat, epidemics, natural disasters, etc. On the other hand, migration makes it possible
to discover new habitats and those areas temporarily suitable. Immigration and emigration within an
existing habitat also provides the necessary genetic exchange to ensure that the variability of the
genetic pool is maintained.
Migrant animal behaviour in contact with a highway
There are several ways in which a migrating individual may react to an encounter with a highway:
1) Change direction and leave the area – this usually happens unless the migration has a clear
direction
2) Follow the highway until a suitable safe passage is found – migrating animals can follow the
highway if their migration has a direction; the distance varies between the species as well as between
individuals of the same species
3) Run across the highway
Animals running across highways present a problem both from the point of view of protecting
populations from the effects of fragmentation and of road safety. A sufficient number of animals
successfully running across highways would virtually eliminate the barrier effect of highways,
however, the attempts of larger animals to cross entails a high risk of collision with vehicles and
consequent traffic accidents. A high road mortality of animals may cause a significant drop in the
population size. The ability of animals to cross a highway successfully varies from species to species.
While the level of success is generally low for ruminants, most carnivores are able to run across
highways more successfully. Exceptions include, however, slow moving badgers or otters. It is very
difficult to establish the actual frequency of highway crossing by animals. Tracking during
exceptionally good snow conditions has shown that the red fox crosses highways during the night
relatively frequently and with a high level of success. Roe deer often come close to highways during
the night, but they cross only exceptionally.
A number of factors determine the frequency of crossing, including:
- The type of surrounding landscape and the concentration of animals
- The elevation of the highway in relation to the surrounding terrain – hoofed animals usually
enter highways in places where the highway is level with the surrounding terrain and there are no
crash barriers
- The age of the highway – there is a higher frequency of animals crossing newly built highways
- Crash barriers - especially deer and wild boar see crash barriers as an obstacle which, together
with the impression of the highway, they prefer not to cross
- Highway fencing
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5. Summary of research to date
The following is an overview of papers, studies and other work used as sources for this
methodology. Most of them are AOPK CZ projects carried out in cooperation with, and with the
financial support of, the Roads and Highways directorate of the Czech Republic. Studies carried out
by the companies Evernia s.r.o. and Valber spol.s r.o. were also used.
5.1. The use of various bridge types by otters (Lutra lutra). In the course of the Eurasian otter
protection program, the usage of various types of bridges was confirmed. Information was collected
by snow and radio tracking of the animals. Some 90 cases of road kills of otters were also analysed.
The result of this was the policy booklet ‘Crossing of overland roads and waterways with the
function of bio-corridors’ (Toman, Hlavac 1995). The Ministry of the Environment officially
recommended the practical application of this policy.
5.2. The evaluation of the present highway and high-speed road network from the point of
facilitating passage for large mammals. In 1998-1999, an intensive research programme connected
with physical controls of highway bridges over the entire Czech Republic was carried out. The
conclusions of this research suggest that the present highway and high-speed road network does not
represent a significant barrier for animals of the size of a fox, a badger or an otter. For animals of the
size of a roe deer, the evaluated highway network facilitates passage over about 40% of its entire
length. A large number of sectors, significant from the migration point of view, remain completely
impassable. In many sectors, highways and high-speed roads present an entirely impassable barrier for
large animals such as red deer and elk. The total extent of entirely impassable sectors represents about
70% of the entire length of these roads. There is also a significant finding that the crossings of
interregional bio-corridors with highways are almost entirely impassable for large mammals. This is
chiefly caused by the fact that the USES (official Czech ecological network) documentation was
mostly prepared at a time when the highways were already in existence or their design was already
approved. We should also mention the paradoxical fact that an interruption of a bio-corridor is not in
conflict with the official USES policy.
5.3. A proposed migration profile handbook for road designers. At the request of the Roads
and Highways Directorate of the Cz. Rep., a basic policy proposal for designing migration profiles for
road designers was prepared in 1999-2000. In the ecological section, prepared by Evernia s.r.o.,
fundamental ecological factors were evaluated and a migration potential theory defined. The technical
part completed by Valbek spol. s r.o. provides an overview of various types of migration constructions.
5.4. A classification of the territory of the Cz. Rep. with respect to the diffusion of large
mammal species. The solution of passage through line barriers in an area must be supported by a
sound knowledge of the diffusion of the various species of large mammals. For the purpose of this
methodology, the current numbers of the followed species were established in 2000 using the standard
mapping network of the KFME system. Generally, the occurrence for all species was evaluated in five
categories – from areas with regular occurrence to areas with no occurrence. On the basis of the data
on the occurrence and migration of large mammals, a map showing the occurrence of large mammals
within the Czech Republic was created. This map divides the territory of the Cz. Rep. into five
categories – from the most important areas to entirely insignificant areas (see enclosure).
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5.5. Evaluation of practicality of various types of passages for specific species of large
mammals. This evaluation is based upon the observation of a selected sample of 100 bridges during
the time they were covered with snow in 1999-2001. For the purpose of observation, underpasses 5-60
m wide, six overpasses 6-8 m wide and one ecoduct were selected. The sample included passages with
various terrain conditions. All tracks found within 100 meters on both sides of the passages, as well as
the tracks of the animals who went through the passage, were included. Of the total of 100 passages,
roe deer used 18 underpasses and one ecoduct, passages of wild boars were recorded through 8
underpasses and passages of red deer through 5 underpasses.
The observations confirmed that the best parameter for the expression of the suitability of
underpasses was the index:
Width x Height
Length
Width – the width of the underpass (the dimension parallel to the axis of the road)
Height – the height of the underpass
Length – the length of the underpass (the dimension perpendicular to the axis of the road)
The observations confirmed a considerable difference between the uses of underpasses with
identical indexes located on different highways. On Highway D1, roe deer used only those
underpasses with an index higher than 20, whilst on other highways (for example, D2 and D5),
underpasses with significantly smaller dimensions were used (even with an index under 1). These
findings can be considered conclusive and show that size is not the only significant factor for the actual
usage of passages. The observations have further shown:
•
•
•
The smallest underpass proven to be used by roe deer had the following dimensions: w=10 m,
h=1.8 m, l=28 m, index 0.64
The smallest underpass used regularly by wild boar had dimensions w=55 m, h=10 m, l=28 m,
index 19.64. According to unverified information, wild boar have also been irregularly using an
underpass measuring w=12 m, h=5 m, l=60.5 m, index 0.99
The smallest underpass regularly used by red deer measured w=55 m, h=10 m, l=28 m – index
19.64. A single passing of a sika deer through an underpass measuring w=55 m, h=6 m, l=28 m
– index 2.06, was also recorded.
Note: The above minimum dimensions for roe deer were observed only on one occasion and
therefore must be considered an exception. The use of bridges of this category is a consequence of an
exceptionally favorable composition of other factors that affect the passage. These dimensions should
not be considered a guideline for the design of new passages (see Chapters 9 and 12).
6. Affected animal species
Habitat fragmentation mainly influences species inhabiting large areas and with a relatively low
population density; therefore, the most threatened species are usually large mammals. Small mammals
are usually not significantly affected by the presence of highways, as those populations inhabiting
sectors restricted by networks of highways are usually large enough for long-term survival. Moreover,
small mammals usually have plenty of possibilities to pass the highway in the form of numerous tube
underpasses unsuitable for bigger animals. In this handbook, therefore, a greater level of attention is
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paid to medium or larger sized mammals, such as the red fox, the otter, the badger, or larger species.
Emphasis is placed on native species, whose protection has an important sociological value. Introduced
species have been released into hunting grounds, mainly in an attempt to increase the range of game
animals, and their migration and spreading are undesirable. In addition, we did not assess the influence
of habitat fragmentation on the European beaver. The migration possibilities of this species are
influenced by different kinds of construction (e.g. dams, cannelised streams, and so on), and bridges
usually do not represent a significant barrier.
In the following text, a short summary of the characteristics of some of those species most affected
by road construction are presented: i.e. Eurasian Badger (Meles meles), Eurasian Otter (Lutra lutra),
Red Fox (Vulpes vulpes), Wolf (Canis lupus), Lynx (Lynx lynx), Wild Cat (Felis silvestris), Brown
Bear (Ursus arctos), Wild Boar (Sus scrofa), Roe Deer (Capreolus capreolus), Red Deer (Cervus
elaphus) and Elk (Alces alces).
Eurasian badger (Meles meles)
Status – A native species, widespread, the population is stable or slowly increasing in numbers.
Distribution – Occurring over the whole territory of the Czech Republic, regular occurrence is
confirmed from 92.7% quadrats of the Czech Republic.
Habitat – The species favours woodlands; in lowland areas with intensive agricultural production
the population density is lower.
Migration - The Eurasian badger lives in territorial social groups (or clans). Members of the same
clan share an area of, on average, up to 2 km of the main set. The size of home ranges depends on the
carrying capacity of the habitat, reaching up to 400 - 500 ha in the Czech Republic. The yearlings start
to disperse in autumn, but the highest dispersal activity occurs in spring. Migrations of young animals
may be up to 12 kilometres or more.
Eurasian otter (Lutra lutra)
Status - A native species, formerly widespread, but by the end of the last century it had started to
disappear from industrial areas with canalised and polluted watercourses. The numbers and distribution
appeared to reach its minimum in the 1970’s. Due to the improving quality of the environment, the
population has steadily increased over the last decade. The recent population level is estimated to be at
least 700 - 800 individuals.
Distribution - Recent data indicates three main relatively isolated populations. The largest is that
found in the southwest of the country, in the Sumava area, the Czech Moravian Highlands and the
lowland pans around Ceske Budejovice and Trebon. The second population is that found in the
northeast of the country, in the Beskydy Mountains with connections to Poland and Slovakia. Finally,
there is a small population in the north of the country along the borders of Poland and Germany.
Habitat - Inhabits all types of aquatic habitats from oligotrophic mountain creeks to slowly floating
lowland rivers, wetlands, fishponds and water reservoirs. May regularly travel several kilometres over
land between catchments. The basic environmental requirements are good fish availability and at least
partly preserved natural banks of watercourses and reservoirs.
Migrations – Compared to other similarly sized carnivores, the otter is highly mobile. Radio
tracking has revealed daily movements of up to 30 km in some areas. The average distance travelled by
an otter during one night in the Czech-Moravian Highlands reached 7.5 km, with most movements
occurring within its home range. The otter is territorial for most of the year, but during the winter
males often appear to travel for long distances. The movements are primarily limited to watercourses,
including small tributaries. A network of roads interlaces the landscape inhabited by man, and otters
appear to avoid those bridges or small underpasses entirely filled by water, or those with long dark
passages. Though local individuals may become acclimatised to these passages, and subsequently use
them more frequently, migrants appear to avoid them and they usually overcome them by running
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cross the road. In cases of high road traffic, repeated deaths of otters may occur. Such unsuitable
crossings of streams and roads may become a dangerous barrier to migration.
Red fox (Vulpes vulpes)
Status - Species widespread. Annual game bags have steadily increased since the mid 1960’s. It is
considered as a vermin species and is hunted year-round.
Distribution - Inhabits the whole of the Cz. Rep.
Habitat - A highly adaptive species, found in various habitats including human settlements
Migrations - A territorial species, the size of a territory varying between 20 and 2000 ha. The
males’ territory usually includes the territories of several females. Increased movements are recorded
during the breeding period and during the dispersal of young animals, which usually occupy territories
within a radius of 15 km from the natal den. Long distance migrations have not been recorded in the
Cz. Rep.
Wolf (Canis lupus)
Status - A rare and protected species, sporadically immigrating from Slovakia or Poland
Distribution – The wolf disappeared from the Cz. Rep. between the 18th and 19th centuries, with the
last bags of stray animals occurring at the end of the 19th century. Today, single individuals, or even
small packs, may immigrate into the Cz. Rep. as numbers increase in Slovakia. At the present time,
permanent occurrence is recorded only in the Beskydy Mountains area.
Habitat - Inhabits well-preserved wide-ranging woodlands, but is able to populate even cultural
landscapes.
Migration – The size of territory of a single social unit (one pair or pack) varies between 900 – 1200
km2 (Finland), 50 – 700 km2 (Ukraine), 70 – 200 km2 (Italy), and 60 - 70 km2 (Bulgaria). The territory
size depends mainly on food availability, and is usually smaller during the summer. The distance
travelled during the vagrancy period can reach more than 60km per day and, during chases of prey,
distances of 200 km per day have been recorded. Single individuals can wander over hundreds of
kilometres.
Lynx (Lynx lynx)
Status - A native species, exterminated over most of the Cz. Rep.. A reintroduction programme,
together with increases in the Slovakian population, has led to re-colonisation in several areas over the
1980’s and 90’s.
Distribution - Recently inhabits four isolated areas. Largest populations were established by
reintroduction in the Sumava area, recently spreading to adjacent areas. Regular occurrence has been
recorded in the Jeseniky Mountains and in the Northwest part of the country (the Labe catchment). The
western part of the Slovak population extends into the Beskydy Mountains. Migrating individuals also
occur in other areas, particularly in the Czech-Moravian Highlands.
Habitat – A typical species of woodlands in mountainous areas, recently also spreading to bigger
complexes of woods and downs
Migration – A solitary living territorial species, with male home ranges of up to 264 km2, and
female’s of up to168 km2. Young animals are expelled to vacant territories, often occupying new
areas. Mutual isolation and the low numbers of the Czech population demand preservation of potential
migration corridors.
Wild Cat (Felis silvestris)
Status - A native species, exterminated from most of the Cz. Rep. between the 18th and 19th
centuries. Single observations and bags during the second half of the 20th century are related to the
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occurrence of stray animals from Western Europe and the Slovak populations. A protected species, it
bears a strong similarity to the domestic cat, which causes problems with the protection of this species.
Distribution - At the present time, frequent observations and findings come from two areas.
Animals migrating from the Slovak population occur in southeastern Morava, whilst individuals
observed in the Sumava area come from reintroduction programmes in Bavaria.
Habitat – Inhabits woodlands, favouring deciduous or mixed forests in lower hill regions.
Migration - A solitary living species with distinctive territories of numbering only tens of hectares.
The occurrence of a few individuals in the eastern part of the country, close to the Slovak population,
indicates relatively low migration abilities.
Brown Bear (Ursus arctos)
Status – A very rare species, occurring marginally in the Cz. Rep. as a projection of the Carpathian
Brown Bear population. During the 18th century, it was exterminated in Bohemia, except around the
Sumava area, where it survived until the middle of 19th century. A recent increase in the Slovak
population has caused migration of brown bears into the Czech Republic.
Distribution – Formerly showing sporadic occurrence in the Beskydy and Jeseniky Mountains, and
exceptionally reaching over the Bohemia-Moravian border, it has recently changed to regular
occurrence in the latter two areas.
Habitat – Inhabits wide-ranging mixed and coniferous woods in mountainous areas.
Migration - A solitary living species with female territories of 58-225 km2 and male territories of
128-1600km2. The high population density of the Slovak population causes migrations (up to several
hundred kilometres long) oriented mainly to the west and southwest. The frequency of these migration
movements has recently increased.
Wild Boar (Sus scrofa)
Status – Common and widespread over the whole of the Cz. Rep., with irregular occurrence close to
large settlements and lowland areas with intensive agriculture production. The species was
exterminated at the beginning of the 19th century, and has again re-colonised the Cz. Rep. following the
Second World War. The population was steadily increasing until the beginning of the 1990’s, however,
since then, a small decrease has occured following an epidemic of swine plague. It is a year-round
hunted species with annual bags of up to 60 000 individuals (1991).
Distribution - Widespread over the whole country.
Habitat – Prefers woodlands from lowlands to highlands and often visits cultivated fields and the
vicinity of human settlements for feeding.
Migration - A Highly mobile species and non-territorial. It tends to move in family groups,
travelling distances of up to 40 km per night. Migrations are determined mainly by current food
availability. The species is a common casualty of road traffic.
Roe Deer (Capreolus capreolus)
Status - A native species and an important game species. Annual bags show fluctuations in numbers
every 7-9 years. Recently, numbers have slightly decreased in some regions.
Distribution – Common and widespread over the whole of the Cz. Rep. from lowlands to highlands.
Habitat – Favourable habitats are downs with mosaics of small woods, fields and meadows.
Migration – Roe deer show varied patterns of social behaviour. Usually during November, roe deer
form winter herds. These herds occupy areas of 40 to 812 ha in areas covered by rape, winter wheat
and lucerne. The herds start to split in the middle of March. The quality of environment strongly
influences territory size, varying from 3 to 7 ha in forest habitats, and from 3 to 40 ha in field habitats.
Overlapping home ranges are much larger and their size changes with season. Winter home ranges in
field habitats vary between 40 to 812 ha, between 25 to 386 ha during the spring break-up and, during
11
the formation of territories and parturitions, between 6 do 30 ha. No migration tendencies have been
recorded in the Cz. Rep., as compared with populations in other areas of Europe.
Red Deer (Cervus elaphus)
Status - A native species, occurring in over a large part of the Republic. Approximately 49% of the
country has regular occurrence, whilst the species occurs irregularly over an additional 33%. The
actual area occupied by the red deer has decreased over the last decade due to a decrease in numbers in
highland areas.
Distribution – Permanent occurrence is concentrated in wide-ranging woody borderlands. Inland
populations occur around Brdska vrchovina, Zdarske vrchy and Drahanska vrchovina.
Habitat - Woody areas in mountainous and sub-mountainous regions in southeast Morava,
including floodplain forests.
Migration – The red deer is a typical social living species. During the year, seasonal changes in
group composition and changes in relations between particular social categories are more or less
regular. Groups of females with calves form in July. Out of the rutting season, red deer associate in
separate groups, occupying different habitats from females with calves. Male groups start forming after
the rut.
Two types of regular movements are known:
a) seasonal feeding migrations
b) movements during the rut.
Both cases usually consist of migrations of only several kilometres, but 50-60 km long movements
have been recorded. Irregular migrations, when red deer leave areas of high population density and
displace into new areas, also occur. Such random migrations interconnect all areas of permanent
occurrence.
Elk (Alces alces)
Status – A native species, exterminated between the 12th and 15th centuries. The first migratory
animals started to occur from 1957, due to increasing populations in Poland. Three stable populations
have gradually established in the Czech Republic, those in Jindrichohradecko, in Posumavi and in
Nymbursko. All micro-populations hold only several tens of individuals and recent population trends
appear to be decreasing.
Distribution – In recent times, regularly occurance was established in 8 quadrats from theose areas
mentioned, data on migrating individuals from 1970-1993 comes from 203 quadrats.
Habitat – Marshland and woodland areas
Migration – Elk populated the Czech Republic in three successive stages. Between 1957 and 1966,
the elk occurred in the Cz. Rep. only sporadically. Immigrating animals were generally young males
migration in a southwesterly direction. By the end of the 1960’s and the beginning of the 1970’s, the
number of immigrating animals had increased, with equal sex ratios of migrants and protracted stays.
The elk is considered as a member of Czech fauna since 1974, when the first birth was observed in
Jindrichohradecko. The main migration route occurs between the Frydland promontory and the town of
Nachod and follows the whole of the Czech-Polish border between the village of Vidnava and the town
of Jablunkov. The migration route continues through the western part of the Czech-Moravian
Highlands or the middle and lower part of the River Sazava catchment to populations established in
southern Bohemia. The elk is solitary or lives in small groups of 1 to 4 individuals. Groups comprise
females and calves. Only during the winter period do bigger associations form at good feeding places.
The elk is not territorial and its movements are influenced mainly by food availability, weather, and
level of disturbance.
12
The peak of daylight activity occurs in the morning and in the evening. Daily movements range
between 1-6 km. During periods of high snow cover, movements are very limited. Seasonal migrations
of tens of kilometres occur in some areas. Migrations of around a hundred kilometres occur during
searching for new habitats. The first immigrants came to the Czech Republic from the Polish
population, 400-500 km distant.
Introduced species, such as as sika deer (Cervus nippon), fallow deer (Cervus dama), white-tailed
deer (Odocoileus virginianus), moufflon (Ovis musimon), barbary sheep (Ammotragus levia), chamois
(Rupicapra rupicapra), wild goat (Capra aegagrus), or racoon dog (Nyctereutes procyonoides), could
also be influenced by the barrier effect of highways. As mentioned earlier, these species were
introduced to the Czech Republic for hunting purposes. Their migration and spreading to other parts of
our territory is considered as undesirable, with high risks for native fauna and flora. Only moufflon
(regular occurrence in 273 quadrats), fallow deer (regular occurrence in 200 quadrats), and sika deer
(regular occurrence in 58 quadrats) occupy a significant area of the country (43,5%, 9,2%, and 31,8%
respectively). Their requirements for permeability of highways are probably the same as those of
native species of similar size categories.
13
Table 1: Overview of medium and large mammals in the Cz. Rep. and their migration behaviour
Czech name
(Latin name)
Eurasian badger
(Meles meles)
Racoon dog
(Nyctereutes proc.)
European beaver
(Castor castor)
Eurasian otter
(Lutra lutra)
Red fox
(Vulpes vulpes)
Wolf
(Canis lupus)
Lynx
(Lynx lynx)
Wild cat
(Felis silvetris)
Brown bear
(Ursus arctos)
Wild Boar
(Sus scrofa)
Roe Deer
(Capreolus capr.)
Moufflon
(Ovis musimon)
Fallow Deer
(Cervus dama)
White-tailed Deer
(Odocoiles
virginianus)
Barbary Sheep
(Ammotragus levia)
Chamois (Rupicapra
rupicapra)
Wild Goat
(Capra aegarus)
Sika Deer
(Cervus nippon)
Red Deer
(Cervus elaphus)
Elk
(Alces alces)
Distribution in CZ
Widespread over the whole country,
territories of 400 – 500 ha
Introduced species
Migration
Territorial species, migration of young
individuals
Migration over the whole country
Catchment of River Morava, down part Migration limited to watercourses
of River Labe and Berounka etc.,
quickly spreading species
Distributed over three relatively
Daily movements up to 30 km, long
isolated populations
distance migrations of males, confined to
watercourses
Widespread over the whole country,
Territorial species, migration of young
territories of 0,2 – 20 km2
individuals up to 15 km
Sporadic occurrence, stray individuals Moving species, travelling up to 60 km
during a single night, long distance
migrations of up to hundreds of km
Mosaic distribution, species is
Territorial species, long distance migration
spreading into new areas
of young animals
Rare occurrence, territories of only tens Sharply territorial species, small migration
of ha
ability
Sporadic occurrence in Beskydy and
Long distance migrations (hundreds of km)
Jeseniky Mountains
Common over the whole country
Moving species, travelling up to 40 km
during a single night, long migrations to
different areas
Common over the whole country
Stationary during the summer, feeding
migrations during the winter
Introduced species, occurs over about Stationary during the summer, associating
40 % of the country
in herds during winter, no long distance
migrations
Introduced species, occurs over about Territorial species
30 % of the country
Introduced species, occurs in game
Random
preserves
Introduced species, occurs in game
preserves
Introduced species, isolated
populations
Introduced species
Random
Introduced species
Random
Random
Random
Wooded highland areas
Regular migrations for feeding and
breeding, irregular long distance migrations
Rare, occurs around Sumava, Taborsko Non-territorial, individuals migrate for long
Jindrichohradecko, , Nymbursko
distances
14
7. Classification of roads according to their barrier effect
Overland roads create a network of barriers restraining the natural movement of animals through
their habitat. This applies to short local movements as well as long distance migration.
The essential factors determining the significance of such barriers are:
1) General technical design – this especially includes the width of the road, its elevation above
the surrounding terrain (embankments, incisions) and additional barriers (noise screens, crash barriers,
fences).
2) Traffic intensity – this determines not only the risk of collision with vehicles when the animal
enters the road but also the level of noise and smell pollution, which has a disturbing and repelling
effect. Night traffic intensity levels are especially significant.
Roads may be classified according to their barrier effect as follows:
3) Highways – usually a minimum of four lanes with central dividers, designed for high speed
traffic (In the Czech Republic, these are highways and high-speed roads). The barrier effect of the road
is produced by the design as well as the high intensity of traffic. Unless a sufficient number of safe
passages are provided they usually represent a complete barrier to migration.
4) Busy standard roads - undivided roads designed for normal speed (in the Czech Republic,
most Class I roads). The barrier effect is caused mainly by the intensity of the traffic; the road design
alone usually does not present a significant barrier (unless the road is fenced). Wild animals are able to
pass across these roads during times of low traffic intensity.
5) Other less busy roads – wild animals can easily cross these roads; neither the road design nor
the traffic intensity present a problem.
Note: The level of the barrier effect does not determine the numbers of animals killed on the roads
(These numbers are often higher on local roads than on highways).
8. Classification of Passages
Table 2 gives the categories of passages and, being based upon the definition of road constructions,
it is consistent with similar classifications in foreign literature.
15
Table 2: Classification of pessages
Culvert
Underpasses
(P)
Bridges on road
Passages
Bridges over the road
Overpasses
(N)
Tunnels
Tube culvert
Framed culvert
Multipurpose bridge
Special bridge
Large bridge, natural
Multipurpose bridge
Special bridge – ecoduct
Special tunnel – ecoduct
Natural tunnel
P1
P2
P3
P4
P5
N1
N2
N3
N4
Overpasses designed especially to allow animal migration are often called ecoducts (N2, N3). They
are divided into two categories due to technical terminology; bridges are defined as overpasses when
up to 50 meters in length (measured on the axis of the road), whereas overpasses over 50 m in length
are called tunnels. The schemes of specific types of passages are included in Appendix 4.
9. Factors affecting the effectiveness of passages
9.1 The condition of the animal population.
The occurrence of a particular species in the vicinity of the bridge, and the density of its local
population, are significant factors affecting the usage of each passage. However, the internal
motivation of the animal for migration appears to be a significant factor in some areas, making use of
passages difficult to predict. This can include, for example, migrations to rutting or wintering areas,
migrations to find food, water, etc. The construction of a road, however, significantly changes the
situation in the area, such that the actual motivation of the migration can be difficult to establish in
advance. In some cases, especially with roe deer, changes in the structure of the local population
following a road construction may also be a factor. During the first few generations following the
construction, territories of individuals in the area may be less stable, the animals reclarifying their
territorial borders, resulting in an increased number of transient and migrating animals. Only several
generations later do the animals start respecting the existence of the new highway and adjust their
territories to the new barrier and any possible passages. This theory could also explain why passages
through new highways are used more frequently than those through older roads. This factor is an
unknown entity in passage design and always brings a degree of uncertainty.
9.2 The condition of the surrounding area.
The structure of the surrounding area may be a further factor affecting passage usage, especially
regarding the location of those aspects attractive to the animals. The area surrounding the road may be
attractive to a certain species, or totally unsuitable for it. It is very important to establish whether the
animals have used it continuously or whether there are obvious migration corridors in an otherwise
intensively agricultural (i.e. unattractive) area. The connection of highway under- and overpasses to
attractive areas is crucial.
16
9.3 Disturbances.
Disturbances will include both those under the bridge as well as those caused by highway traffic.
Disturbances under the bridge may be caused by frequent presence of people and dogs, operating
machinery and vehicles, proximity of human settlements or recreational and other buildings. The
complex of acoustic, olfactory and visual perceptions causes the disturbance by highway traffic. An
animal passing under the bridge is probably most affected by acoustic perceptions, which are a
function of traffic intensity, road surface (concrete panel surfaces are significantly more noisy than
asphalt), design of the bridge, etc.
9.4 Passage dimensions.
In general, the data on minimum passage dimension cannot be considered as a guideline for any
species. These minimum data have only a stochastic character. The probable use of passages by roe
deer, wild boar, and red deer, based on current data, may be described by the following table:
Table 3: Probability of bridge usage in relation to its dimensions
%
Roe Deer
Description
I
Wild Boar
80-100 Ideal stage
> 30
Example
60 x 15:30
60-80
Functional
optimum
Average
7,0 - 30
30 x 7:30
7 – 30
30 x 7:30
8-40
30 x 8:30
1,5 – 7,0
15 x 3:30
2-7
20 x 3:30
4 –8
30 x 4:30
Functional
minimum
Functionless
stage
0,65 –1,5
9 x 2/2:30
1 - 2,0
10 x 3:30
1.7- 4
10 x 5:30
40-60
20-40
0-20
%
I
up to 0,65
I
Red Deer
> 30
Example
60 x 15:30
> 40
Example
80 x 15:30
up to 1,0
I
up to 1,7
probability of use of a bridge of certain dimensions (consistent with the technical migration
potential)
index w x h / l (the width of the underpass multiplied by its height divided by its length)
Notes
• For roe deer and wild boar, underpasses with an index over 30 can be considered ideal. For red
deer, indexes over 40 are ideal. These are usually bridges crossing entire valleys, the area
under the bridge is overgrown and, from the point of view of the animals, it forms a part of the
surrounding habitat (home ranges). The animals usually have no hesitation in using these
bridges. They are used even in situations where there is no “migration pressure” within the
population.
• Functional optimum – these are underpasses, which by their dimensions present certain
resistance to the animals; however, they are regularly used when there is migration pressure.
• Average – these are underpasses, which can be actually functional provided there is a
significant migration pressure, and there is a positive influence of other factors.
• Functional minimum – these underpasses are used only in exceptional cases where there is a
strong migration pressure and an ideal composition of other factors (minimum disturbance,
17
•
bridge on an important corridor, with an optimum area under the bridge and an optimum
connection to the surrounding area).
Non-functional – these are passages where the dimensions limit passage even when the
migration pressure is highest and all other factors are ideal.
9.5 The area under the bridge.
The area under the bridge is often crucial for the usage of the passage by specific species. The area
under bridges, which are to serve as passages for animals, must have an unpaved earth surface,
pavement or gravel is unsuitable. The quality of the passage is often affected by the design of the
storm sewers, by paved trails, reservoirs located next to the bridge, etc. The area under the bridge must
be designed especially in order to enable small animals to pass under cover. The presence of logs,
large boulders and other “naturalizing” effects, rather than an empty space, will facilitate usage.
10. The Migration Potential Theory
In order to respect the stochastic character of the proposed measures, it is practical to use the
migration potential (MP) theory during road design stages. This theory was published in Andel
(2000): “Methodology for proposing of migration profiles” and is verified in field at this time.
Migration potential is defined as the probability of functionality of a migration profile. A migration
profile is functional if it is being used by the animals and provides safe migration through an overland
road.
The functionality of a migration profile is determined by two factors:
1) Ecological – expressed as the Ecological Migration Potential (MPE).
This is determined by the properties of the migration route prior to the road construction. Its
future use must be considered with a view to the development of the larger region. MPE gives the
probability of use of the migration route in the so-called zero event, i.e. when no road is built.
2) Technical – expressed as Technical Migration Potential (MPT).
This is determined by the properties of the migration passage, its design, dimensions and other
aspects. MPT gives the probability of full use of the migration construction by the animals, i.e. the
probability that the original extent of migration will be maintained after the road construction.
The total migration potential is defined as the multiple of the ecological and technical migration
potential: MP = MPE x MPT.
Notes:
•
All forms of migration potential, being stochastic quantities, have values within the interval
<0;1>. MP=0 represents an extreme situation where the passage of animals through a migration
construction is impossible; MP=1 represents an idealised situation where an important and
regularly used route has not been affected by an overland road at all. The actual stages between
the two extremes may be classified and described (see Table 4).
18
Table 4: Classification of migration potential
Migration
potential
1,0 – 0,8
0,8 – 0,6
0,6 – 0,4
0,4 – 0,2
0,2 – 0,0
Utility classification of migration profile
Entirely functional, approaching ideal solution
Above-average, high utility, only small limitations
Average, medium utility, with obvious limiting
components
Under-average, low utility, number of limiting components
Functionless, approaching total impenetrability for
migrating animals
•
The definition MP (MPE x MPT) is based on the mathematical rule which provides that the
resulting probability of two independent occurrences (A1 and A2) which occur simultaneously
equals the multiple of their individual probabilities (P = P1 x P2). This is consistent with the
logic of the problem in hand. It follows that the technical design of the construction cannot
increase the total migration potential above the level prior to the road construction.
•
The concept of migration potential stresses the equal status of the technical and ecological
components. It is obvious, and the fact is quantified here, that no good migration construction
can be built where the ecological as well as the technical conditions are favorable. For example,
in a place where there is a regular and verified animal migration (MPE=0.9) but for technical
and spatial reasons, the proper technical solution is impossible (MPT=0.2), the final effect will
be only low (MP=0.9 x 0.2=0.18). On the other hand, where there is a very low natural animal
migration due to disturbing factors (MPE=0.2), not even an excellent technical solution
(MPT=0.9) can provide a highly functional profile (MP=0.18).
•
The concept of migration potential is based on a quantitative estimation of the level of
functionality and usefulness. Despite all the problems presented by the estimation method, it
forces both the components equally to quantify their capacity within the given profile. An
example is the advantage of this method in evaluating migration routes. Within the framework
of the regional systems of ecological stability (USES), the existing bio-corridors are often not
distinguished from those planned, the functionality of which cannot be estimated. The
distinction is possible by establishing an MPE for each migration route.
• Migration potential is also a useful measure for cost-benefit analysis for the design of migration
constructions. It is possible to compare the cost and the expected effect expressed by the
migration potential for each proposed alternative. This makes it possible to use scarce financial
resources only for those areas where there is a realistic expectation of actual benefit.
19
Part B - Recommended optimal approaches and solutions
This section contains some recommendations for passages through newly constructed highways.
During the design phase, answers to two questions must be found: 1. Where? (determining the
locations where passages need to be built) and 2. How? (setting the optimum dimensions of the
passages).
11. Planning migration passages – the density and location
The setting of distances between passages and suggesting their placement should be undertaken in
several stages. During the road construction design stage, these questions must be considered on
national, regional and local levels.
11.1.
National considerations
The significance of the wider area surrounding the proposed construction is assessed considering the
nationwide occurrence and migration behaviour of each species. From this point of view, areas
connecting isolated populations are considered crucial; these locations may be vital to the continuing
existence of a population even when the particular species does not live permanently in the area. A
further priority are locations where a line barrier would divide a population in the area of its central
concentration. Information contained in this handbook may be used for the purpose of a nationwide
assessment. The area considered would then first be categorised according to the Map of Area
Categorization By the Occurrence and Migration of Large Mammals (see Appendix 4) as one of five
categories. Further, general guidelines have been prepared for these area categories providing the
optimum ways of ensuring the passage of wild animals through highways. The requirements are
general and will be specified by migration studies in the next steps of the evaluation.
I.
Areas of exceptional importance - (areas of central concentration of more than one of the
following species: red deer, elk, lynx, bear, wolf, or areas of main migrations of these species).
For this category, a minimum of new constructions is generally recommended. New road
sections should always be design with a maximum consideration for the passage of large
mammals. The following rules apply to new constructions:
a) They must provide a safe passage for animals the size of a red deer every 3-5 km. Generally,
this would be a large underpass with a WxH/L index over 10 or an ecoduct with a minimum
width of 40 m. The specific dimensions shall be designed after a detailed analysis of local
conditions. See Chapter 12 for details.
b) They must provide a multifunctional underpass with an index over 1.5 every 1.5-2.5 km. This
passage should also be suitable for the migration of reptiles, amphibians, and small mammals
(i.e. they should include stones, bushes, shade). See Chapter 12 for details.
c) They must provide a dry culvert, diameter at least 0.8 m, every 1 km.
II.
Areas of increased importance - (areas of present or expected permanent populations of lynx,
permanent population of red deer, main elk migration areas). Passage must also be provided for
large species. New road sections should always be designed with a maximum consideration for
the passage of large mammals. The following recommendations apply to new construction, i.e.
they must:
20
a) They must provide a safe passage for animals the size of a red deer every 8-15 km. Generally,
this would be a large underpass with a WxH/L index over 10 or an ecoduct with a minimum
width of 40 m. See Chapter 12 for details.
b) They must provide a multifunctional underpass with an index over 1.5 every 2-4 km. This
passage shall also be suitable for the migration of reptiles, amphibians and small mammals (i.e.
they should include stones, bushes, shade). See Chapter 12 for details.
c) They must provide a dry culvert, diameter at least 0.8 m, every 1 km.
III.
Areas of medium importance - (remaining areas of periodical, irregular or future populations
of the following species: red deer, elk, lynx, bear, wolf, or areas of secondary migrations of
these species). New road sections should always be design with a maximum consideration for
the passage of large mammals. The following recommendations apply to new constructions:
a) They must provide safe passage of animals the size of a red deer every 8-15 km. Generally,
this would be a large underpass with a WxH/L index over 10 or an ecoduct with a minimum
width of 40 m. See Chapter 12 for details.
b) They must provide a multifunctional underpass with an index over 1.5 every 3-5 km. This
passage shall also be suitable for the migration of reptiles, amphibians and small mammals (i.e.
they should include stones, bushes, shade). See Chapter 12 for details.
c) They must provide a dry culvert, diameter at least 0.8 m, every 1 km.
IV.
Areas of low importance – (no red deer, lynx, elk, wolf or bear population, though with
regular occurrence of roe deer and wild boar). Passage for large species is not necessary. The
following recommendations apply to new constructions:
a) They must provide a multifunctional underpass with an index over 1.5 every 5 km. This
passage shall also be suitable for the migration of reptiles, amphibians and small mammals (i.e.
they should include stones, bushes, shade).
b) They must provide provide a dry culvert, diameter at least 0.8 m, every 1 km.
V.
Unimportant areas – (no large mammal population – especially large urban conurbations).
There is usually no need for passages for deer and other large species. Where there is a
possible roe deer habitat of at least 1 km2 between the conurbation and the road, a passage
under the road with an index over 1.5-2 may be recommended. There should be at least one
passage for reptiles, amphibians and small mammals on each kilometer, and a passage for foxes
and badgers every 1-3 km.
The recommendations mentioned above are summarised in the following table:
Table 5: Maximum distances of passages for different mammal categories in different areas
of importance
Categories of areas
Mammal category
Cat
Area
Red Deer
Roe Deer
Red Fox
I
Exceptional importance
3–5
1,5 – 2,5
1
II
Increased importance
5–8
2–4
1
III
Medium importance
8 – 15
3–5
1
IV
Low importance
N
5
1
V
Unimportant
N
N
1–3
21
Note: All data presented in km.
N – passages not usually suggested for these categories.
11.2.
Regional considerations
After the nationwide assessment, the impact of the road construction on the immediate area (usually
up to 10 km) must be considered. A 1:50000 map is a good source for this evaluation. For example,
the existence of other barriers in the area (major roads, highways, line constructions, major rivers, etc.)
should be considered, as well as the connection to wooded areas, etc. The result should be a proposal
of the best possible location of passages with an accuracy of 100-1000 m. The results of this
assessment are compiled in a regional migration study.
11.3.
Local considerations
A detailed zoological research study of the area considered must be the basis of the exact placement
of specific passages. Aside from the concentration of each species, the size of the populations and
their location is required. It is useful to take advantage of information from local specialists, forestry
personnel, hunting associations, etc., in addition to biological research. Information about the actual
routes the animals take to find food, water, and rutting places must be collected. A 1:10000 map is a
good source for this evaluation. The data should be specified with an accuracy of 1-10 m. the results
of this assessment are compiled in a local migration study providing a proposal for the exact location
of passages, their dimensions, main design guidelines and a detailed proposal of additional measures
needed (fences, etc.). An ongoing cooperation of the author of the migration study with the road
designer is a necessary condition for the proposed solutions to become realistic. This cooperation must
exist throughout the entire process of construction planning.
12. General guidelines for passage construction (the best manner of providing
passage through a specific place)
Passages can generally be divided into underpasses and overpasses (see Chapter 8). Both types are
comparably effective provided they are designed properly. Therefore, the type of terrain is the chief
factor in deciding whether to use an overpass or an underpass. An underpass can usually be used only
for highways on embankments and an overpass if it is in a cutting. The following factors apply to
specific passages:
12.1.
Ecoducts
These are special constructions designed to facilitate animal migration over a highway. At the time
of writing of this handbook, only one ecoduct was operational in the Czech Republic and, therefore,
the following recommendations are based mainly on experiences from other countries. There are
several construction types and drawings of examples are included in the Appendix. From the point of
view of their function, their width (the dimension in the axis of the road) is crucial. Foreign literature
distinguishes between bridges built for the purpose of providing passage for specific species of large
mammals (“cerviducts”, etc.) and bridges providing connection between various habitats (proper
“ecoducts”). Both types are distinguished by size as well as the placement of vegetation. For special
purpose bridges, the vegetation placement is designed purposely in order to safely minimise the
disturbance and noise caused by traffic. The vegetation placement on bridges connecting habitats must
be designed to facilitate the migration of all types of organisms, including those that move slowly. In
order to use the available financial resources effectively, it is obviously practical to combine both
purposes for new projects, therefore, we will use the single term “ecoduct”. The following principles
should be followed for ecoduct design:
22
•
•
•
•
•
•
Placement – ecoducts should be placed in areas of the most significant migration, i.e.
especially in areas of expected red deer, elk and large carnivore migration. Ecoducts may be
advantageously placed in areas where the highway is in a cutting. Where the highway is level
with the surrounding terrain (flat land), the construction of ecoducts is also possible; however,
extensive annexation of land will be required. When selecting the ecoduct location, places
where animals are naturally led to should be selected; however, other migration factors should
also be considered (e.g. there should be no other significant migration barrier within several
kilometers.
Dimensions – many studies in foreign countries deal with the dimension parameters of
ecoducts. The parameters are usually given separately for landscape bridges (provision of the
interconnection of habitats and biotopes) and for wildlife overpasses (connecting particular
species populations). The minimum recommended width of wildlife overpasses is 7 metres for
the migration of roe deer and wild boar, and 8-12 meters for migration of red deer or elk. The
standard width of landscape bridges is 45m + 5m, and exceptionally 25m + 5m. The minimum
parameters given are applicable only in places with optimal composition of other factors (e.g.
high migration pressure, no disturbance, optimal vegetation arrangement, natural connection to
surrounding landscape). The minimum width of landscape bridges ensuring interconnection of
habitats and biotopes should exceed 50 meters. The ecoducts in the Cz. Rep. should serve
mainly for migration of red deer, elk, and other large carnivores, hence the standard width of
40-50 meters is recommended. A significant decrease in the width is possible only in the case
of serious construction obstacles; the distance of 40m at the entrances of ecoducts should be
preserved. This solution is justified also in the case of the upgrading of existing objects.
Vegetation arrangement of ecoduct – is basic factor influencing the usage of ecoduct. The
vegetation should allow migration of maximum number of species, withstand extreme soil and
hygric conditions and be enough stabile. Above-mentioned reasons often exclude achievement
of locally native species composition. Native species of bushes and short growing trees should
be favoured. The hazel, blackthorn and whitethorn are species suitable for most conditions in
CZ, in lowland areas the species composition can be enriched. Spatial distribution of the
vegetation is more important than its species composition. Dense vegetation at edges of ecoduct
provides cover and protection from disturbance caused by road traffic. The middle part can be
more open to allow easy passage of large species.
Minimisation of traffic – disturbance at the ecoduct should be reduced to a minimum. If
unpaved field or forest roads for occasional transport are proposed, the dimensions of the
ecoduct should be correspondingly widened. No road should be proposed on ecoducts
narrower than 40m.
Reduction of technical elements – this mainly includes the reduction of lighting (lighting at
the entrance under the ecoduct must not lighten the middle part of the ecoduct). All concrete
constructions, drainage constructions, etc. should be excluded from the ecoduct.
Connection to the surrounding landscape is also an important factor influencing the usage of
ecoducts. Vegetation on ecoducts connecting two separated forests represents an optimal stage
and maximum migration pressure can be expected at such places. If the highway splits one
forest, their interconnection by an ecoduct is also possible, but it is necessary to guide the
animals to the ecoduct by fences. Vegetation on the ecoduct should connect the seperated parts
of the forest.
Schemes for basic construction types of ecoducts are presented in Appendix 3.
23
12.2.
Multipurpose overpasses
This kind of passage is not widely used. Migrating animals tend only to use overpasses with field
and forest roads. Overpasses with busy roads are usually not used at all. Winter tracking revealed only
limited usage of such overpasses, mainly by hare, stone and pine martens and, rarely, by red fox. A
relatively easy modification of existing overpasses could markedly increase the number of species
using them. Such modifications should especially include:
•
•
•
•
•
•
replacement of open steel railings by filled railings (e.g. wooden) with a minimum height of
1,2 m
providing good conditions for the growth of at least climbing vegetation along the railing
unpaved surface of the road (i.e. earth)
maximum shortening of bridging (the slopes should be filled in place of bridging)
widening of entrances to the overpass
perfect connection to the surrounding landscape
The realisation of such modifications could ensure the permeability of overpass with a minimum
width of 7m even for roe deer (in places with extra high migration pressure). Minimum disturbance is
an essential condition influencing the usage of such overpasses. It should be noted, however, that the
theoretical recommendations given above have not been tested in practise as yet. The assumed usage of
such modified overpasses will depend to a great degree on the precise realisation of all details in the
technical design and vegetation arrangements.
12.3.
Special underpasses
Special underpasses are also not a common solution. Special underpasses are mainly needed in
places where it is not possible to solve migration problems by modification of existing objects, areas
where road crossing is high, and where migration pressure is very high. They are classified according
to target species, such as those for:
•
Underpasses for otters and badgers – the requirement for special underpasses for otters and
badgers is high mainly in countries with high habitat fragmentation. The modification of
unsuitable bridges and culverts seems to be sufficient to allow the migration of both species in
the Czech Republic (see Chapters 12.4. and 12.5). Special underpasses for these species are
mainly needed on existing roads with unsuitable bridges and culverts, where the collisions of
passing animals with cars are common. A suitable solution for both species may be a pipe with a
diameter of 25 or 30 cm passed under the road. The entrance to the underpass should be
highlighted by the arrangement of vegetation and relief, and often through the use of guidance
fences. It may be neccesary to discuss the technical details for the passage with experts for the
particular species.
•
Underpasses for animals the size of roe deer or wild boar – special underpasses proposed
for roe deer and wild boar are also usually used by other smaller animals. It is possible to
increase the attractiveness of such underpasses for small vertebrates (including reptiles and
amphibians) by only slight changes in design. Such underpasses, therefore, should be built using
a multipurpose design with respect to small vertebrate requirements. The dimension index (H x
L/W) should exceed 1.5, and have a minimum height of 2.5 metres. All kinds of disturbance
should be reduced to a minimum. The ground underneath the bridge should always be unpaved,
24
i.e. of earth. The provision of cover, e.g. logs, roots, small stones, etc., can also increase the
passages attractiveness for small animals. A good connection to the surrounding landscape is
also fundamental, with vegetation in the vicinity of the passage’s entrance connected with
surrounding vegetation. The design of the bridge ‘ending’ at the embankments may also notably
in fluence usage of the bridge. The optimal solution would entail the bridge endings having
embankments at an angle of 45 o, naturally guiding migrating animals under the bridge.
•
Underpasses for red deer and elk – These underpasses have similar requirements as the
previous type of underpass, but the minimum dimension parameters should include an index
(HxL:W) exceeding 4 (optimum about 10) and a minimum height of 3m.
12.4.
Multipurpose underpasses
Such multipurpose underpasses are potentially the most used type of passage by animals. Bridges
over watercourses, less frequented overland routes, railway bridges and valley bridges may especially
be used for migration. These bridges must satisfy the basic requirements specified for special
underpasses if they are to serve as passages for animals; many, however, differ in the minimum
dimension parameters needed for their migration function. The available space at an underpass may be
narrowed by accessory measures such as crash barriers, ditches, etc. And, therefore, the dimension
parameters should be modified according to the traffic intensity and technical appearance of the
overland route. In this case, even minimum traffic intensity should be considered at bridges at less
frequented roads.
The width of a watercourse and the character of its bed are especially important. The watercourse’s
bed and bank may often be ‘improved’ (i.e. strengthened by concrete, etc.) and most animals tend not
to use such ‘improved’ beds and banks. The width of unused (i.e. semi-natural) space of rivers with
improved banks and bed should always be included in the proposal of minimum dimension parameters
of a bridge. A natural character for the watercourses, including their banks, should be preferred and a
strip of dry land must be available under any bridge over large watercourses. This strip should be at
least 50 cm wide to allow the migration of foxes, badgers, otters and other similar sized animals, and at
least 5m wide to allow the migration of roe deer.
Valley bridges tend to be built in places unsuitable for the construction of embankments or in places
threatened by floods. These bridges are used by all species of animal without limitation. The minimum
height, however, is important and should be at least 2m for roe deer and 2.5 - 3m for red deer.
12.5.
Culverts
Culverts are mostly designed to transport occasional precipitation, or small permanent waters. When
they are dry, they are often used as underpasses by animals of the size of fox, badger, or otter. The
following basic principles should be respected during their design if they are also to serve as
underpasses:
• The end of culverts should project beyond the fencing of highways.
• There should be no sediment chamber with vertical sides at the entrance to the culvert. These
chambers are very often represent traps for small animals (amphibians, small rodents,
hedgehogs, etc.).
• Culverts should be built without a gradient, thereby preventing blockage by flooding.
• If culverts are used to transfer permanent water flows, a frame type including an unpaved
bottom should be preferred. Tube culverts with a permanent water flow are not useable for most
species.
• Both entrances to the culvert should have a natural appearance and animals must be guided into
it naturally.
25
•
If culverts are designed for migration of amphibians, both ends of the culvert must be without
barriers, i.e. without obstacles higher than 10 cm.
12.6.
Specifics of constructions of passages in lowlands
Underpasses in lowland areas should be proposed in places with a high migration pressure and
minimum disturbance. However, it is often very difficult to formulate projects for any type of passage
in lowland areas as the achievement of the minimum height needed for the underpass requires a
marked elevation of the vertical alignment of the highway over the surrounding terrain. Similarly,
locating the passage may also prove to be a problem. The resulting plan is usually very expensive and
may be unacceptable for landscape ecologists.
In lowland areas, roe deer are the species most likely to require passages. In this case, an underpass
with a height of 2.5m should be sufficient under optimal conditions; whilst the minimum width of the
underpass (when the highway has an average width of 30 m) will be 18 m, with an index of 1.5. If the
required height of the underpass is 3 m, the minimum width of the passage will be 15 m (these
measurements will give a high probability of usage if disturbance is minimum and migration pressure
is high). A small elevation of the level of the highway, and\or a lowering of the surrounding terrain,
could be used to achieve the minimum height needed. It is quite possible that the soil in the resulting
depression may become waterlogged. The subsequent development of wetland vegetation in these
areas may increase the attractiveness of the passage for many species, as well as making the passage
less accessible and attractive to people. In general, the slope of any guiding embankment leading to the
entrance of a passage, should not exceed 10%, otherwise passage usage may be reduced. However, it
is possible that the neighbouring land needed for such guiding embankments will be already occupied.
Therefore, not only does this varient require strong technical solutions, ownership of the plots of land
surrounding the passage must also be solved.
Similar problems also affact the placing of ecoducts. Ideally, embankments covered with vegetation
are necessary for their construction in lowland areas. However, whereas similar constructions have
already been built in several countries in Europe (e.g. Hungary), it is not likely that they could be used
widely in the Czech Republic.
12.7.
Reduction of noise in the vicinity of all types of passages
The noise caused by highway traffic is likely to be an important factor influencing the intensity of
usage of passages, although the full effects of such noise on wildlife has not been well studied as yet.
Though most mammalian species are able to acclimatise to relatively high levels of noise (red foxes,
for example, often occupy dens in highway or railway embankments, and even in close vicinity to
extremely noisy military airports; and roe deer often rest in scrubby highway embankments) noise,
together with other kinds of disturbance, will affect the intensity of usage of individual passages. High
traffic levels cause high levels of noise and the elimination of this type of disturbance is not possible,
however, it is possible to reduce the amount of noise in the surroundings of passages. Possible
solutions include:
•
Placing a 100-150 cm high noise screen over the underpass; this will also serve as a visual
barrier separating the entrance of the underpass from the highway.
• Similar opaque noise screens may also be suitable for overpasses, especially smaller passes.
• Materials that produce less noise should be used when constructing, or re-constructing,
highways (e.g. do not use concrete panels); particularly at those stretches over or under the
passage.
• The placement of bridges could also be important; bad positioning, resulting in increased noise,
could result in the avoidance of an otherwise suitable passage.
26
13.
Accompanying measures
Aside from the various kinds of passages, the design and usage of other accompanying measures
may further reduce the risk of collisions between animals and passing cars. In the Czech Republic, the
design of highway fencing and crash barriers are an especial cause of problems, whilst the pattern and
type of maintenance of vegetation along highways also has a strong influence on the numbers of
collisions. The provision of warning sings and signs limiting maximum speed have proved useful;
whist other detterant methods, such as reflectors, mirrors, olfactory or ultrasound repellents, have been
experimentally used in other countries, though their use is not as yet common. In northern Europe, a
complex system of sensors in combination with traffic lights has been used; when an automatic sensor
such as a photocell is tripped by a passing animal, a signal switches on traffic lights on the highway. In
Scandinavian countries, this method is used in places with regular migrations of elk and reindeer.
13.1
Fencing
The main aim of fencing on highways should be the prevention of colisions between crossing
animals and passing cars. Whereas the ideal solution on any road would be the provision of a sufficient
number of passages of all the types mentioned above, together with total fencing of the complete
stretch of road, practice demonstrates that the possibility of realising this is difficult, if not impossible.
Fencing, to remain effective, must be kept in perfect condition. If there is a hole, animals often pass
through, become disorientated and try to escape, colliding with the fence and, in the end, collide with a
passing car. If fencing is too short, or is constructed badly, similar problems may occur as animals pass
the ends of the fence. The correct positioning of fences is also important. Fencing should be erected
between the regularly mown grass zone along the crash barriers and the begining of any wood or bush
vegetation. Locating fences at the begining of an embankment slope with accessory vegetation, often at
a distance of many metres from the highway, is unsuitable. People, wild boar, and agriculture machines
frequently damage such fences and they mey also act as ‘traps’, in a similar way to that mentioned
above. By locating such fences behind the grassy zone, frightened animals are able to seek refuge
within the bushy vegetation, or to leave the highway altogether. If the fence is outside of this
vegetation zone, frightened animals often look for refuge within the accessory highway vegetation and
try to get into the fenced space. In the case of wild boar, this attempt is often successful. However, the
optimal location of fencing ensuring animal safety may cause problems for highway maintenance and
traffic safety. Fencing placed in close vicinity to a highway could, in exceptional cases, prevent the
escape of people from dangerous situations. It is not possible, therefore, to propose explicit
recommendations for the location of fences, the situation being solved in concordance with local
conditions.
The ends of culverts placed within fenced areas also frequently constitute problems. For example, if
one end of a culvert is situated within the fenced area, and the other outside of it, this may constitute a
trap for animals; alternatively, if both ends are inside the fenced area, the culvert does not function as a
safe passage.
The assessment of the positive impact of fencing at highways is not always clear; when it is
functional, it can significantly reduce the number of collisions, however, full and safe functioning is
probably impossible in practice. Further, fencing can even increase the barrier effect of less frequented
highways. Fencing, therefore, may only be necessary in sections with high migration importance, but
they should be provided with a sufficient number of safe passages for animals. Continuous checking of
27
the integrity of the fencing is necessary and all defects must be immediately repaired. This requirement
must also be ensured in sections where the fences cannot be checked from the highway.
The above principles should be respected for each construction project proposed. The exact range
and location of fencing, however, should be ascertained for each construction project within the
framework of a migration study. Due to the complexity of the problem of fencing, it will also be
examined in the others phases of this project.
13.2.
Crash barriers
The main purpose of crash barriers is not to prevent animal crossing, however, some do form a
barrier, at least for certain species. The common type of steel crash barrier, under normal conditions,
need not be a barrier for roe deer or wild boar, however, in combination with other factors connected
with highway traffic, they may form a significant migration barrier for many species. Full concrete
crash barriers also constitute a problem for badgers, otters and foxes, as they represent a complete
barrier to movement. Animal collision risks at sections of road provided with crash barriers tend to be
low, however, problems can arise at sections where crash barriers end. Were crash barriers end should
receive extra attention during the preparation of any construction project, ideally ending in places with
a low probability of animal movement.
13.3.
Maintenance of vegetation in the neighbourhood of highways
The maintenance of vegetation along the highway can have a significant influence on the level of
risk for an animal crossing the highway. Ideally, a 5 m wide strip of grass, regularly mowed, between
the road verge and the beginning of any bushes or woody vegetation should be allowed. This zone is
not only less attractive for animals, it provides extra time for both the animal and the driver to see each
other.
14.
Integration into Czech Ecological Network and Land Use Planning
Providing adequate passages through the road network is only one step in ensuring free migration
throughout an area. A Central European type landscape, with a high density of human settlements,
contains many other types of barriers, such as built up areas, areas of intensive agriculture, etc. The
habitats of many species often have the character of islands, with areas which no longer support their
permanent existence separating the populations. The opportunities for interconnecting existing habitats
are decreasing steadily, and suitable habitats are gradually being reduced to narrow corridors. Our
laws provide for the protection of these corridors through national, regional and local networks of
Territorial Ecological Stability Systems (USES).
Facilitating passage through highways must always be based on the wider territorial contexts of the
surrounding area. One of the most important sources for information for such projects must always be
the materials, plans and projects prepared by the USES. Their advantage is their legislative
interconnection and land use planning, which guarantees future protection of any USES units. At the
same time, it must be emphasised that a requirement for free passage through a proposed section of a
highway must not be reduced to the issue of providing a passage at an intersection of a highway with a
USES bio-corridor. In all cases, we must consider the occurrence of individual species, their migration
needs, the wider context of migration in the area and, last but not least, the specifications of the terrain
in the location.
An important issue connected with land use planning is also the future use of the land adjacent to
the planned passages. It can easily happen that at the time of the construction of a highway, the
problem of passage is solved; however, later, construction is approved in places where it limits the
function of the passages or renders them impassable. This type of construction then causes the
28
impassability of the line barrier and also contradicts the purpose of the previous investment into the
passages.
The following principles should ensure the integration of highway passages into the USES and land
use planning:
•
•
•
•
Passages through line barriers must always be considered within the wider territorial context,
keeping in mind the status of the landscape and the distribution and migration of individual
species.
One of the vital sources for planning passages through highways is USES material at all
levels.
Facilitating wild animal passage through highways cannot be limited only to resolution of
the intersection with USES units.
Design of passages must always include the issue of land-use in the area, which is a
condition of the functionality of the passages. Prevention of unwanted construction or
disturbing activities may have various forms (contract with the owner of the land, including
the land among USES units, registering a building prohibition, etc.). It is usually not
possible to require this of the investor in the highway construction and, in this case, the
initiative should come from the appropriate environment protection agency.
15. Facilitating passage in specific stages of planning and approval of construction
Principles:
• The issue of animal migration must be involved at all stages of investment planning of roads and
highways.
• Throughout the planning period, the interconnection of the biological and technical aspects of
the solution must be maintained (The proposals for location of the passages come from
biological information; however, their technical practicality needs to be assessed, etc.).
The essential steps in biological and technical planning and their interconnection are provided in
Table 6. Note that this is just a general scheme and the actual design procedure may deviate from it. It
is important, however, not to leave out any of the required steps. In order to minimize the barrier
effect of overland roads, all the steps in Table 6 are necessary. From the practical point of view, the
majority of decisions are made in Stages (3) – EIA Process, (4) – land use planning permits and (5) –
materials for building permit.
Notes:
Technical Study and Environment Impact Assessment (EIA)
In most cases, a suitable version of the route is selected at this stage. Therefore, it is necessary to
consider animal migration aspects in the final selection. In most cases, EIA documentation is based on
a technical study, which is usually prepared from existing maps (not an exact terrain survey), further
updates, therefore, must be expected during the following stages.
Recommendations:
•
An independent migration study evaluating the general migration potential of the route,
suggesting migration construction types to be used, and generally confirming their feasibility,
must be included in the EIA documentation.
29
•
The issue of providing migration passage through the route must be included in the criteria for
the final selection of design alternatives. The importance of this issue will depend on the
specific local situation in connection with the categories of areas in the Czech republic (see
Appendix 1).
Documentation for Land Use Planning Decision
At this stage of design planning, a precise geodetic survey of the terrain is carried out to specify the
direction and elevation of the route. In some cases, there may be significant differences from the
technical study, especially in elevation. These might be important for the migration construction.
Recommendations:
• Specify passage dimensions by calculating their migration potential.
• Verify the general facilitation of passage throughout the section in relation to minor changes of
the route.
• Update the required dimensions of individual migration constructions in relation to the updated
facilitation of passage.
Documentation for Building Permit
At this stage of design planning, the route has been set and detailed technical documentation of specific
components are being prepared. As the details (vegetation, area under the bridge, material choice, etc.)
has a significant impact on the total effectiveness of a passage, sufficient attention must be paid to this
stage. An ecologist should be involved in designing these details (at the present time, ecologists are no
longer involved at this stage).
Recommendations:
• Prepare details of individual passages.
• Landscape design of the surroundings of the passage providing connection to the area.
• Involve an ecologist in the above.
16. Facilitating passage in other types of line barriers
All findings and recommendations mentioned above are also useful for the design of other types of
line barrier, especially for railway corridors and first-class roads. The main specific principles for
these types of construction are:
16. 1.
First-class roads (mostly roads with 2 or 3 carriageways, without a middle dividing
zone)
The barrier effect of this category of overland route is not caused by their technical parameters, but
is mainly caused by the intensity of traffic. Contrary to highway type roads, it is always necessary to
take into consideration the passing of animals over these roads. Continuous fencing of these roads is
unreallistic (due to frequent crossroads, beginnings of forest roads, etc.) and is also unsuitable in
respect to protection of populations (fencing increases barrier effect causing high habitat
fragmentation). Therefore, fencing should be limited only to exceptional cases, where frequented road
intersect the place of high migration of animals and where safe passage is available. It is also possible
to use more traffic warning signs and signs limiting speed for these roads (compared to highways).
The clarity of road verges and the neighbouring environment is also a critical factor.
The dimensions of passages recommended for highways, expressed by the index: height x
width\length, are also applicable for first-class roads.
30
16. 2.
Railways corridors When planning fencing for railway corridors, the proposed
frequency and parameters of passages will be based on similar principles as those for highways.
Problems regarding accessory measures, such as the provision of vegetation on slopes and incisions,
the type and location of fences, etc., should be solved during the assessment process of the proposed
constructions.
Table 6:
Essential steps in the biological and technical planning of passage constructions
Phases of
Technical aspects
investment
Level of
Documentation
General
preparation
importance
of roads
1
Transport
Transport policy State policy
conception
of nature
protection
2
Selection of
Territorial plans Ecological
corridors
+
assessment
Prospecting
(Landscape
study
assessment)
3
Selected variant Technical study EIA
(Documentat
ion)
4
Stabilised
route
Land use
planning (DUR)
5
Detailed project
Materials for
building permit
(DSP)
6
Realisation
Inspection
7
Operation
Ecological aspects
Migration of animals
Aims
Ensuring the
survival of
species
Facilitating
permeability of
the area
Selection of
specific
migration
profiles
(verification of
practicality)
Elaboration Specific
of EIA
technical solution
conditions
(Technical
parameters)
Elaboration Detailed
of conditions technical solution
(DUR)
(connections to
other parts –
drainage,
vegetation
arrangement)
Control of
Inspection of
conditions
construction
DSP
Monitoring Inspection of
(post project effectiveness
analysis)
(monitoring)
Documentation
Classification of
territories
Supra-regional
consideration
Migration studies
Determination of
parameters of
passages
Detailed project
of passages
Documentation
of inspection
Evaluation of
migration
(monitoring)
31
17.
Conclusion
Habitat fragmentation is becoming a crucial limiting factor for the survival of many animal and
vegetable species. In the Czech Republic, and in Central Europe generally, the rapid increase in
transport infrastructure, and particularly in line constructions such as highways, motorways and
railway networks, is significantly reducing the connectivity of the landscape for animals. An essential
requirement for the survival of many species in the future, therefore, is to ensure a sufficient quantity
of appropriately designed passages allowing free movement and migration of as many species as
possible.
This methodology is the first attempt to provide a comprehensive evaluation of the available data
and knowledge on this important problem. The aim has been to formulate general recommendations
reflecting the actual status of our knowledge. The level of knowledge on this issue will continually
increase and, therefore, this methodology must represent the first step in an ongoing process of
updating and refinement.
32
18. Literature
•
Anděl, P.2000: Metodika pro navrhování migračních profilů pro zvěř, záv. zpráva, MS 29pp ŘSD
ČR Praha
•
Anděra M. & Hanzal V. 1995: Atlas rozšíření savců v České republice. I. Sudokopytníci
(Artiodactyla), zajíci (Lagomorpha). Národní muzeum, Praha, 64
•
Anděra M. & Hanzal V. 1996: Atlas rozšíření savců v České republice: II Šelmy (Carnivora).
Národní muzeum, Praha, 86.
•
Anděra M. & Kokeš O. 1978: Migrace losa (Alces alces L.) v Československu. Čas. slez. Muz.
Opava (A) 27: 171-188.
•
Bartoš L. 1997: Etologie. In Vach, M. (ed.): Myslivost. Silvestris, pp 58-85.
•
Bekker B.J. 1995: Handreiking maatregele voor de fauna langs weg en water. Dienst Weg- en
Waterbouwkunde Rijkswaterstaat,
•
Bekker H. & Vastenhout M. 1995: Nature across motorways, Rijkswaterstaat. Dienst Wegen
Waterbouwkunde, Delft,
•
Bobek B., Kosobucka M., Perzanowski K. & Plodzien K. 1992: Distribution and wolf numbers in
Poland. In: Promberger, Ch. & Schröder, W. (eds.): Wolves in Europe – status and perspektives.
Proceedings of the workshop, Oberammergau, Germany, Bundesministeriums für Verkehr und der
Forschungsgeselaschaft für Straßen- und Verkehrswesen e.V. , Heft 756,
•
Bützler W. 1986: Cervus elaphus Linnaeus, 1758 – Rothirsch. In: Niethammer J. & Krapp F. (eds.)
Handbuch der Säugetiere Europas. Band 2/II. Paarhufer. AULA-Verlag Wiesbaden, 462 pp.
•
Eriksson I.-A. 1995: Enviromental Impact Assessment for Roads. Swedish national Road
Administration,
•
Eriksson I.-A. 1996: Assessment of the ecological effects of roads and raiways. Recommendations
for Methodology. Swedish national Road Administration,
•
Eriksson I.-A. 1998: Gotheburg – Jönköping Transport Corridor. Enviromental Impact of Strategic
Choices. Swedish national Road Administration,
•
Fritzer H.1993: Drundsätze des Gewässerschutzes and Strassen. Wien,
•
Hell P. 1992: Current situation and perspektives of the wolf in Czechoslovakia. In: Promberger
Ch. & Schröder W. (eds): Wolves in Europe – status and perspektives. Proceedings of the
workshop, Oberammergau, Germany. Bundesministeriums für Verkehr und der
Forschungsgeselaschaft für Straßen- und Verkehrswesen e.V. , Heft 756
•
Hlaváč V. & Toman A. 1999: Vyhodnocení průchodnosti dálniční sítě ČR z hlediska velkých
savců. AOPK ČR, středisko H.Brod - závěrečná zpráva úkolu. MS dep. AOPK ČR
•
Hlaváč, V. a kol. 2000: Rozšíření a migrace vybraných druhů savců v České republice
•
Hlaváč, V., 2001. Fragmentace krajiny a ochrana velkých savců, Ochrana přírody 1/2001,Praha
•
Hlaváč,V.,a kol, 2001: Sledování průchodnosti vybraného vzorku mostů a statistické vyhodnocení
výsledků, AOPK ČR, stř. Havlíčkův Brod, závěrečná zpráva úkolu 7 pp. MS dep AOPK ČR
•
Huber D. & Roth H. U. 1993: Movements of European Brown Bears in Croatia. Acta Theriol 38:
151- 159.
•
Koubek P. & Hrabě V. 1996: Home range dynamics in the red deer (Cervus elaphus) in a mountain
forest in Central Europe. Folia zoologica 45: 219-222.
33
•
Kyek M. 1998: Amphibienschutz an Sraβen. Empfehlugen für den Straβen, Institut für Ökologie
Arenbergstraβe Salzburg,
•
Lešák L. 1999: Migrace velkých savců přes silnici I/4 Hřebene Betaně. Orchis Strakonice,
•
Matyáštík T. 1999: Rozšíření jezevce lesního (Meles meles) na severní Moravě a jeho potravní
chování. Diplomová práce, Katedra zoologie a antropologie PřF UP Olomouc,
•
Matyáštík T. & Bičík V. 2000: Dynamika populace jezevce lesního (Meles meles) na Prostějovsku.
Přírodovědné studie Muzea Prostějovska 3: 95-103.
•
Matyáštík T., Bičík V. & Řehák L. 2000: Jezevec lesní - jeho biologie a význam v ekosystému.
Praha, Venator,
•
Müller S. & Berthoud, G. 1997: Fauna / Traffic Safety – Manual for Civil Engineers. Lausanne,
Switzerland,
•
Peters G. 1993: Canis lupus Linnaeus, 1758 – Wolf. In: Stubbe M & Krapp F. (eds.): Handbuch der
Säugetiere Europas. Band 5/I Raubsäuger. 1993 AULA-Verlag Wiesbaden
•
Pfister H. P., Keller V., Georgii B. & Reck H. 1997: Bio-ökologische Wirksamkeit von
Grünbrücken über Verkerswege, Forschungsberichte aus dem Forschungsprogramm
•
Proceedings of the international conference „ Habitat fragmentation, infrastructure and the role of
ecological engineering,, Maastricht (1995), ISBN 90-369-3727-2
•
Rosenberg D. K., Noon B. R. & Meslow E. C. 1997: Biological Corridors: Form, Function, and
Efficacy. BioScience 47/10:
•
Toman A. & Hlaváč V. 1995: Křížení komunikací a vodních toků s funkcí biokoridorů. Metodika
AOPK ČR,
•
Swenson J. E. 2000: Action plan for the conservation of the Brown Bear (Ursus arctos) in Europe.
Účelová publikace Rady Evropy, Strasbourg,
•
Völk F. & Glitzer I. 1998: Konstenreduktion bei Grübücken durch rationellen Einsatz. Institut
fürWildbiologie und Jagdwirtschaft der Universität für Bodenkultur, Wien,
•
Zejda & Nesvadbová 1983: Habitat selection and population density of the badger (Meles meles)
in Bohemia and Moravia. Folia zoologica 32 (4): 319-333.
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