Wildlife corridors and their effects on brown bears (Ursus arctos): a survey of Alberta citizens on knowledge and attitudes

Master's Thesis, 2002

94 Pages, Grade: 2 (B)


Table of Content


List of Figures

List of Tables

1. Introduction
The conservation of brown bears
The situation of brown bears in Alberta
Current situation
Hunting, laws ands compensations – as contributing to brown bear mortality and dispersal
What do Alberta citizens think about brown bears

2. Barriers and Wildlife Corridors
Conservation theory
Types of corridors
Ecological corridors
Dispersal corridors
Home range corridors:
Gene flow corridors
Gene flow 1
Gene flow 2
Gene flow 3
Designing wildlife corridor networks
Wildlife corridor and habitat patch design
Regional habitat patches
Local habitat patches
Primary or multi-species corridors
Secondary corridors
Core areas and multiple use zones
Stepwise approach to determine shape, size and width of wildlife corridors and habitat patches
Starting point for wildlife corridor and local habitat patch design
The effects of roads and other artificial barriers on brown bears
Roads and Railways
Problem wildlife and habituation
Mitigation methods
Overpasses and Underpasses
The Bow River Valley Corridor

3. Survey among Alberta citizens regarding their attitudes toward and knowledge about brown bears
Valuing wildlife
Attitude toward bears
Questionnaire design
Sample frame and sample size
Sampling procedure
Study areas
Reliability measures
Attitudes toward bears scores
Attitude toward usefulness of bears score
Attitudes toward further bear population development score
Attitude toward bear management score
Knowledge about bears score
Results and Discussion I: Basic findings by item and sample group
Attitude toward bears
Usefulness of bears
Attitude toward further bear population development
Attitude toward bear management
Knowledge about bears
Results and Discussion II: Factors affecting attitudes toward bears
Socio-demographic factors
Perception of the population size
Experiences with bears
Fear related questions

4. Conclusions

5. Summary

6. Literature

1. Questionnaire
2. Statistics
3. Abstract (submitted at the Fourteenth International Conference on Bear Management and Research)
4. Poster

List of Figures

Figure 1. Historical and current distribution of grizzly bears in Alberta

Figure 2. Possible design for a wildlife corridor network

Figure 3. Core areas surrounded by a buffer zone

Figure 4. Proposal for an optimal design for a corridor network

Figure 5. Wildlife corridors and habitat patch shapes

Figure 6. Widths for different corridor lengths

Figure 7. Wildlife corridor width and local habitat patch size for different vegetative cover values

Figure 8. Influence of topography on wildlife corridor width and local habitat patch size

Figure 9. Wildlife corridor widths and local habitat patch size for different vegetative cover values

Figure 10. The Bow River Valley connecting two important wildlife habitats: Banff National Park and Kananaskis Country

Figure 11. Phases of the Trans-Canada-Highway and locations of the 22 wildlife crossing structures

Figure 12. Wildlife overpass in Banff National Park

Figure 13. Animal jam in the Bow River Valley

Figure 14. Factors affecting attitudes toward wildlife

Figure 15. Target audience and sample size

Figure 16. Attitude level by respondents´ sex

Figure 17. Knowledge level by respondents´ sex

Figure 18. Attitude and knowledge by target group

Figure 19. Students´ perception of the bear population in Alberta

Figure 20. Attitude toward bears by students´ perception of the population size

Figure 21. Students´ sightings of black and/or brown bears

Figure 22. Attitude level by students´ sightings of black and/or brown bears

Figure 23. Students´ sightings of brown bears

Figure 24. Attitude level by students´ sightings of brown bears

Figure 25. Students´ perception of the danger of grizzly bears

Figure 26. Attitude level by students´ perception of the danger of grizzly bears

Figure 27. I would be afraid to go into the woods if bears are present

Figure 28. Respondents´ fear in relation to their attitude

List of Tables

Table 1. Potential advantages and disadvantages of corridors

Table 2. Starting point for wildlife corridor and local habitat patch design

Table 3. Sample frame and sample size of the two target groups (absolute numbers and numbers in %)

Table 4. Items used to form the “attitude toward bears” scale

Table 5. Intercorrelations between the “attitude toward bear scale” items

Table 6. Items used to form the “attitude toward usefulness of bears” scale

Table 7. Intercorrelations between “attitude toward usefulness of bears” items

Table 8. Items used to form the “attitude toward further bear population development” scale

Table 9. Intercorrelations between “attitude toward further bear population development scale” items

Table 10. Items used to form the “attitude toward bear management” scale

Table 11. Intercorrelations between “attitude toward bear management” scale

Table 12. Items used to form the “knowledge about bears” scale

Table 13. Intercorrelations between “knowledge about bears” items

Table 14. Results to the items concerning attitude toward bears in %

Table 15. Results to the items concerning usefulness of bears in %

Table 16. Results to the items concerning attitude toward further bear population development in %

Table 17. Results to the items concerning attitude toward bear management in %

Table 18. Results to the items concerning knowledge about brown bears in %

1. Introduction

The conservation of brown bears

“If all the brown bears are gone from the landscape we would be spiritually impoverished.” was the response from a researcher when she was asked why we should protect bears. This is only one of numerous answers to this question.

Bears engage our interest, as do few other wild animals. But brown bears are not simply fascinating animals, they also play an important role in the ecosystem. They are considered 'sustainable farmers'. Many species, both plants and animals, profit by them. Brown bears dig much for food and thereby they stimulate plants to reproduce. Some Canadian scientists even consider grizzlies, conspecific with the Eurasian brown bear, to be an ecological keystone. “Without the grizzlies atop the food chain,” they say, “the West’s delicate mountain ecosystem would crumble.” They think that it could set off a chain reaction that would see other large animals become extinct. Coyotes and other predators would move in and do serious damage to the ungulate population. Grizzlies prey on live ungulates far less than coyotes or wolves. The bears´ presence keeps other predators at bay. Other scientists such as Stephen Herrero, the head of the Eastern Slopes Grizzly Bear Project, do not believe in such dire predictions but Stephen Herrero agrees that the relationship between bears and the rest of the ecosystem is very complex (Sillars 1998).

However, large carnivores, like grizzlies, have been considered indicators of health or integrity of an ecosystem (Paquet and Wierzchowski 1997a) and thus make them useful focal species for large-scale conservation. Landscapes that retain viable populations of brown bears are often ones where natural vegetation predominates, where most native species can still be found, and where ecological processes operate essentially as they have done for a long time (Paquet and Jack Wierzchowski 1997a).

Habitats of brown bears can be huge, but vary greatly on individuals. A modest female can manage to live within a few square kilometres, and long distance travellers among grizzlies, that are mostly males, could need up to 1500 km², which is as big as Kootenay National Park in Alberta or only a bit smaller than the Austrian “Hohe Tauern National Park”, the biggest national park in Central Europe.

In the study area, the Central Canadian Rockies, female brown bears do not begin breeding until they are four - six years old and then they produce on average significantly less than one cub a year. Therefore brown bears in these areas recover slowly if at all from population declines, and only if negative factors have been brought under control (Gibeau and Herrero 1994). Habitat loss, fragmentation, and isolation are the most common causes of species extinction. As natural areas continue to be disrupted by human activities, animal and plant populations become isolated in “island habitats” where genetic inbreeding, depredation of large species, and proliferation and domination of human-adapted species all interact to increase rates of extirpation (Cutler 1991). The basic theories of island biogeography are that the larger the habitat the more species can be secured. As it is not always possible to protect big areas and even if we try to, restricted areas we fashion will never be big enough for some species. Therefore we must begin linking them with corridors for the movement of animals and the dispersal of plant seeds (Waller 1991).

The situation of brown bears in Alberta


Historically, North American grizzly bears roamed the western half of the continent. Brown bears probably came from Eurasia to Alaska about 100,000 years ago. They began to expand their range southwards after the last ice age, some 13,000 years ago, when an ice-free movement corridor along the eastern foothills of the Rocky Mountains was created. Both people and grizzlies used this corridor at about the same time (Herrero 1997). After their population increased, there was an estimated number of 6,000 grizzlies in what is now Alberta. This estimate was based on an assumed density of at least one bear/100 km² across around 600,000 km², which constitutes Alberta (Kansas 2002). During the 1700s, grizzly bears were still abundant in the prairie region of Alberta, especially along rivers that had suitable food supplies like berries, roots and carcasses of drowned bison. They could be found on the prairies as far east as the Red River valley in Manitoba. Whether one looks at the history of grizzly bear populations in the contiguous United States or in Canada a similar picture emerges. Before Europeans tamed North America, the population size of grizzly bears was relatively stable. Bears played a part in the spiritual life of most Native Americans (to many of their descendants they still do) and therefore they killed brown bears only occasionally. In the adjacent United States, the population is estimated to have declined from a pre-European number of perhaps 100,000 down to a current population of 1,000. Settlement of Europeans, agriculture and industry brought about a steady decline in bear habitats and populations throughout much of their range. During the 1800s, explorers and fur traders shot grizzlies for safety reasons, for sport and for the money their pelts would bring. The species was still abundant in areas of southern Alberta in the 1850s. However, the beginning of settlement, ranching and farming during the 1870s spelled the end of the grizzly bear on the prairies. By the 1880s they were all but gone from the prairies of Alberta[1]. Since they have lived restricted in the wildest parts of the Rocky Mountains, foothills and boreal forests of western Alberta.

illustration not visible in this excerpt

Figure 1. Historical and current distribution of grizzly bears in Alberta

(Gibeau et al.1996)

Current situation

Today there are some 1,000 grizzlies remaining in Alberta. In 2000, the total estimated grizzly bear population for provincial land[2] was 841[3] (Kansas 2002). According to Alberta Fish and Wildlife Grizzly Bear Management Plan (1990) the total population of grizzly bears in Jasper, Banff and Waterton National Parks is 215 bears (Kansas 2002).

The total proportion of provincial lands (excluding national parks) that grizzlies occupy in Alberta is approximately 34% (200,000 km²/584,784 km²) (Kansas 2002). Including Banff, Jasper and Waterton Lakes National Parks, they occupy 35% of the province (Kansas 2002).

Grizzly bear ranges in Alberta include the Rocky Mountains and higher portions of the Foothills Natural Regions and the Boreal Mixedwood region in west-central and north-western Alberta (Kansas 2002). They have been compressed from their former range into a narrow strip of land 30-60 km wide between the Continental Divide and the prairies to the east (Gibeau and Herrero 1994). Contiguous to their home range at lower elevations are regions that support grizzly bears seasonally. These areas are usually closer to high density human settlements (Kansas 2002).

In the study area, the Central Canadian Rockies, grizzly bears occur at low population densities, only one bear for each 60-100 square kilometres (Gibeau and Herrero 1994). The number of grizzly bears in Banff National Park is currently unknown, but it is estimated that the population is in the order of 60 bears (Kansas 2002).

The most highly developed area where grizzlies still exist is Banff National Park, situated in the heart of Alberta’s Rocky Mountains. About 1,000 000 people live within a few hours drive of occupied grizzly bear habitat. A further problem represent the almost five million park visitors each year and the fact that they need to travel the Trans-Canada Highway to get to this national park. This highway cuts through the Bow River Valley, which is an important migration corridor for wildlife travelling between Banff National Park and Kananaskis Country[4]. While there is very strong support both nationally and provincially to conserve carnivores in this area there is also enormous public pressure for quality backcountry recreation in the Bow River Valley.

Hunting, laws ands compensations – as contributing to brown bear mortality and dispersal

Hunting, both essential procurement of food or trophy hunting is part of almost every culture. The first inhabitants of Alberta, the Native Indians, hunted bears only occasionally. After killing a bear they addressed its spirit and asked for forgiveness. When North America was tamed by Europeans, settlers profoundly affected the population and distribution of grizzly bears. People using firearms caused rapid extirpation of grizzly bears in many areas.

Presently, management and conservation issues are being hotly debated in Alberta. Some people argue that although grizzly bears are scarce in some regions in Alberta, the population is thought to be stable enough to permit a limited cull. Others say the hunt should be stopped until an accurate count can be made. Hunting of symbols, such as brown bears, will always remain controversial (Sillars 1998).

Bears protection on provincial land in Alberta started in 1927. In 1928 bears were classified as a “fur-bearing” animal and as “big game” in 1929.

South of the 55th parallel, hunters were restricted to two bears per year, of which only one could be a grizzly. The legislation closed the bear-hunting season from June 15th to September 1st and prohibited the taking of cubs and females with young at their side (Gunson 1997).

According to the `General Status of Alberta Wild Species ´ 2000, the grizzly is considered “May be at Risk” (blue listed)[5] in Alberta (Kansas 2002).

On a national basis, the `Committee on the Status of Endangered Wildlife´ in Canada (COSEWIC) designated the brown bear as “vulnerable”[6] in 1991 (Wart 1999).

At present, hunting brown bears in Alberta is possible but only in specific areas during a specified season, which is between April 1st and May 31st.

Since 1988 grizzly bear licenses are only available to residents of Alberta. The bag limit is one grizzly per year. Grizzlies are hunted by a Special License, which is obtained through a draw (lottery) process. About 1200 residents apply for 160 grizzly hunting licences each year, and on average hunters have to wait 7 years to be drawn (Gunson 1997).

On an average, 10 to 15 brown bears are actually shot each year. This relatively small number is explained by the time of the season. At this time of the year, many brown bears are still in their dens, especially the protected females with cubs. It is also unlawful to hunt a grizzly bear under the age of two years or a grizzly bear that is part of a group of two or more grizzly bears. Hunting is prohibited in national parks (Alberta Environment 2000).

Alberta charges resident grizzly hunters a draw levy ($3.04), a Wildlife Identification number fee ($8.00), a Wildlife Certificate fee ($22.85) and a Big Game License fee ($48.59), for a total of $82.48 (Busch 2000).

Grizzlies that are shot must be registered at an `Alberta Environment Protection office´. Hunters must submit both the skull and skin with evidence of the bear’s sex still attached at the time of inspection; this includes the scrotum in the case of a male and a teat or portion of a mammary gland in the case of a female (Busch 2000).

Brown Bears occasionally kill livestock. Between 100 and 200 incidents of bear predation (black and brown bears) occur each year in Alberta (Gunson 1997).

Damage prevention and compensation programs are available to assist producers with most wildlife damage.

Any producer whose livestock (cattle, sheep, goats, bison, hogs) are killed or injured by wolves, bears, cougars or eagles, may file a claim with the local `Natural Resources Service´ (NRS) office within three days of learning of the death or injury. Insurance is not required.

The `Wildlife Predator Compensation Program´ provides compensation for livestock killed, or for veterinary treatment of livestock injured by predators. Claims for confirmed predator kills are paid at a rate of 85% of the average commercial market value for an animal of the same type and class. Claims for probable predator kills are paid at a rate of 50%. Probable kills are those kills with insufficient evidence to confirm that a predator killed the animal, but where evidence suggests that it was a reasonable possibility, and a confirmed predator kill has occurred within 10 km and 90 days of the kill under investigation. The maximum compensation for veterinary costs for injured livestock will not exceed the compensation available to the producer had the animal died (Alberta Environment, 2000).

During 1974-1993, an average of CDN$ 406 was paid on 1,536 approved claims. Cattle counted for 81% of livestock predation; sheep and swine about 9% each. Most of the cattle (71%) were calves (Gunson 1997).

Producers play an important role in minimizing losses to wildlife. They are requested to dispose dead animals in a sanitary manner – carcasses should be burned, completely buried or shipped to a rendering plant.

Sick or weak livestock, as well as birthing and newborn livestock, should be brought in from pastures and kept near human habitation. Predators are less likely to frequent areas where there is regular human activity. If predation recurs in a particular pasture, livestock should be moved to a new area (Alberta Environment 2000).

What do Alberta citizens think about brown bears

The best conservation plan for brown bears will not work without the acceptance of the public. Human dimensions are a crucial factor for the governmental objectives of allowing viable populations of brown bears to develop (Zimmermann et al. 2001). Successful wildlife management involves not only an understanding of the biology of the species and its habitat, but also an understanding of public attitudes toward and knowledge about the species (Bath 1994). Manfredo et al. (1996) stated: Managing wildlife is 10% biology and 90% managing people (Szinovatz 1997). For brown bears and other large carnivores that often arouse conflicting emotions among the general public, the factor of human dimensions is especially important to understand when designing and implementing specific issues of management plans, e.g. wildlife corridors (Bath 1994).

“Does educational work lead to higher acceptance?” was the main question of this study.

Through a questionnaire, a survey about the attitudes toward bears and bear management as well as knowledge about bears was carried out in two study areas in Alberta, Canada. The general attitude of the target groups toward bears as well as factors that affect the attitude (socio-demographic factors, knowledge, fear and experiences) were also examined.

2. Barriers and Wildlife Corridors


First, in 1936, Simpson used the term corridor to describe situations in which two biogeographically separate regions came close enough to exchange fauna (Simpson 1940). At this time, corridors were considered on a much grander, continental scale.

More recent views of corridors as mechanisms to maintain connectivity within a landscape began with Preston (1962) who concluded that a park could not retain the complete inventory of fauna that would occur in a larger area, but corridors between reserves may prevent isolation and total faunal collapse (Preston 1962).

MacArthur and Wilson (1967) followed with the “Theory of Island Biogeography.” This theory states that the number of species on an oceanic island represents a balance between immigration and extinction. They proposed that habitat islands, created through habitat fragmentation, were similar to true oceanic islands and suggested that the number of species that would reach equilibrium on these habitat islands was a function of the area and the degree of isolation from a mainland source. As an area became more isolated, its natural diversity would decrease until it reached a new, lower equilibrium (MacArthur and Wilson 1967).

The use of corridors as a method to decrease the isolation of habitat fragments and thus decrease the likelihood of losing natural diversity was proposed by Wilson and Willis in 1975 (Wilson and Willis 1975).

Levins (1970) introduced the metapopulation model.

The fundamental metapopulation model is an interconnected group of populations where there is interchange of individuals. Some populations may experience local exterminations, but recolonisation by connected populations prevents the overall extinction of a species (Merriam 1991).

The conservation movement soon adopted the idea that populations need connections among patches, and that the solution for the conservation of many species consisted of multiple reserves linked by corridors (Harrison and Voller 1998).


Although the definitions of linkages vary, all imply that there are connections or movement among habitat patches. Corridor is another term commonly used to refer to a tool for maintaining connectivity.

The following are a few definitions of wildlife corridors and connectivity:

1. “A wildlife corridor is a linear remnant of vegetation, unlike the surrounding vegetation, that connects at least two historically connected patches” (Saunders and Hobbs 1991).
2. “A wildlife corridor is a naturally occurring or restored strip of landscape that connects larger patches of similar habitat; the strip functions as a movement route for individuals or for gene flow of native fauna and flora” (Harris and Atkins 1991).
3. “Connectivity is maintained in a landscape when there is a continuity of habitats and processes along environmental gradients. Connectivity of ecological processes (e.g. dispersal, predation, fire, flooding) is as important as connectivity of habitats” (Noss 1991).

Conservation theory

By all means, corridors should not be an excuse for further fragmentation. The best conservation strategy is still to protect areas of suitable habitat as large as possible, because continuous suitable habitat secures more individuals of a species than does fragmented habitat. Small populations, because of random normal variability in demographics, are more likely to become extinct than larger populations. Moreover, small populations are more vulnerable of inbreeding and environmental disturbances such as forest fires and diseases (Paquet et al. 1994). Large areas do not only secure more individuals, even above the level of a `minimum viable population´ (MVP) but also more species. The basic theories of island biogeography say that if we graph the number of species against the size of habitat remnants, the resulting relationship demonstrates that the larger the habitat it supports more species. For each unit of habitat, the number of species increases by an order of magnitude (Butler 1997). Many ecologists believe the deleterious effects of fragmentation can be reduced with landscape linkages among subpopulations (Paquet et al. 1994). However, corridors need not always be profitable. Different species disperse through different types of habitat. A corridor to one species might be a barrier or a “filter” (Simpson 1940) to another. A strip of forest through agricultural land, for example, would provide a corridor for dispersal of forest animals (such as black bears) that avoid clearings, but it could form a barrier to such species that need open landscapes (such as meadow vole) (see table 1).

Table 1. Potential advantages and disadvantages of corridors

illustration not visible in this excerpt

Types of corridors

In biology, motion occurs at many levels of organization. Of most relevance to conservation biology is the movement of organisms across landscape and the movement of alleles within and among populations of organisms. Many animals make daily and seasonal movements to meet life-history needs, and depend on corridors to do so (Noss 1991). Dispersal and gene flow are key features of these movements. Dispersal is the movement of organisms away from their place of origin; gene flow is the movement of alleles due to the dispersal of gametes of offspring (Noss 1991).

Ecological corridors

Dispersal corridors

[subadults in search of suitable habitat]

In many species of terrestrial mammals, dispersal away from their parents is common as they approach breeding age. If their habitat is fully occupied, they may have to travel long distances to find a place to live. Those animals that disperse may use a corridor that has enough resources to sustain them in transit but does not have all the resources necessary to maintain a breeding pair throughout their lifetimes. The physical attributes of this type of corridor vary for different species. Brown bears as generalist omnivores can use a very broad spectrum of habitat types, and therefore dispersal corridors for brown bears are designed primarily by lack of human cultivation – mainly remote, roadless areas with food and cover. Dispersal corridors function to maintain gene flow at level 1 (Paquet and Wierzchowski 1997b).

Home range corridors:

Animals also need to move within their home ranges from one type of habitat to another. These movements can be regular and predictable depending upon the species and the season or they can be stochastic in nature. Then it depends on varying climatic conditions and availability of food or other resources (Paquet and Wierzchowski 1997b).

Migratory corridor – between established winter and summer range

The greatest movement and use of corridors for many ungulates occur during seasonal migrations between summer and winter ranges (Paquet and Wierzchowski 1997b).

Occasional corridor – dependent upon annual climatic factors

Brown bears use many kinds of food. It varies in abundance from year to year, and season to season. Grizzlies will move to areas with good berry crops in the fall. If it is a year with few berries but good white bark pine cone production, grizzlies will concentrate in the fall in areas of white bark pine. Seasonal movements also differ depending upon sex and age class. If good berry or white bark pine habitat is dominated by aggressive, adult males, for example, females and sub adult males will avoid those areas and forage in less desirable habitat (Paquet and Wierzchowski 1997b).

Daily or weekly use corridor

An animal’s use of habitat varies throughout the day and from day to day. Often, regular corridors of movement are used. Many species move regularly between resting and foraging habitat. If they feed in meadows in the early morning they may move to more secure, perhaps shaded, habitat during the midday to rest, the return to foraging areas in the evening (Paquet and Wierzchowski 1997b).

Gene flow corridors

Gene flow 1

This occurs within a single generation. It generally happens when a dispersing individual (often a subadult male) moves from its natal home range to a more distant area where gene frequencies in the local population are somewhat different from its own. For brown bears gene flow 1 occurs through regional corridors (Paquet and Wierzchowski 1997b).

Gene flow 2

This represents the movement of alleles from one population to another over several generations. Alleles are passed on from one individual, who disperses, to its offspring who also disperse, to their offspring who also disperse. Gene flow 2 occurs in brown bear populations on a continental scale (Paquet and Wierzchowski 1997b).

Gene flow 3

This is the movement of alleles over even longer genetic distances. It requires many generations for an allele to be introduced from one population to another. Populations connected by gene flow at level 3 are quite distinct from one another. They have unique alleles and probably unique co-evolved gene complexes. In a genetic sense such populations may be regarded as subspecies with local adaptations. Gene flow 3 occurs over evolutionary, rather than ecological time scales (Paquet and Wierzchowski 1997b).

Designing wildlife corridor networks

The expression establishment of wildlife corridors leaves the impression that we are constructing something new on the landscape. But fundamentally, the corridor strategy is an attempt to maintain or restore natural landscape connectivity, not to build connections between naturally isolated habitats.

However, in a very fragmented landscape there is in fact habitat restoration needed and that animals can pass barriers, there is the need of a construction of underpasses, tunnels and viaducts (Noss 1991).

The flip side of the corridor strategy is to minimize barriers. Urban areas, agricultural fields, clearcuts, and roads make dispersal difficult or dangerous for many forest-interior and wide-ranging species (Noss 1991).

Krebs (1988) calculated an estimated size of protected contiguous habitat for grizzly bears with 122,330 km². He used a population size of 500 animals, a number estimated as a minimum viable base population for long-term survival considering genetic and environmental constraints. Assuming a minimal viable population of 50, Dueck (1990) estimated that brown bear populations require an average of 49,000 km² (Paquet et al. 1994). Single reserves of this size do not exist anywhere in Central Europe or temperate North America.

The most important step for establishing wildlife corridors is to find the right position. Animals might not use a corridor if it is at the wrong place. Adequate research on traditional travel corridors should be carried out. But it is not possible that researchers enter into every species. Therefore it is good to orientate on particular species. Not all wildlife species react equally to human induced change. Some species such as brown bears and wolves (Canis lupus) are especially vulnerable to loss of habitat and human disturbance. Many such species are considered `keystone species´ and if keystone species can persist in an area then it is believed species lower down the food chain are expected to remain at viable population levels as well. The loss of keystone species may even affect interspecific associations by disrupting mutualistic relationships or food webs. This, in turn, may cause secondary extinctions or unanticipated ripple effects in populations of other species (Paquet et al.1994).

However, by maintaining brown bears and the natural ecosystems upon which they depend, the habitat and populations of many other species are also maintained.

The first step and the most inexpensive method in designing a reserve is to assess the status quo of the intended area.

The next step is to categorize the area into wildlife corridors and habitat patches according to their size and shape.

The term habitat patch is defined as an area big enough to support large carnivores over a relatively short time.

A wildlife corridor is described as an area providing connectivity between habitat patches. It is generally not designed to fulfil any of the requirements of habitat patches other than some elements of security, such as sufficient vegetation cover, without these basic requirements animals would not use the corridor (Bow Corridor Ecosystem Advisory Group 1999).

To give an example, the Bow Corridor Ecosystem Advisory Group (BVEAG)[7] which is a partnership between the Municipal District of Bighorn, the Town of Canmore, Banff National Park, and the Provincial Government, used the following system to categorize the study region:

Wildlife corridor and habitat patch design

Regional habitat patches

Regional habitat patches are the entities of wildlife corridor networks. They are large enough (>10 km²) to contain adequate resources to sustain large carnivores for short periods of time.

Local habitat patches

A local habitat patch is meant to meet the food, rest and water needs of an animal for a short period. Due to their small size these habitat patches do not meet the animals needs. Thus most of the local habitat patches, given that they meet the conditions demanded, aim to develop into regional habitat patches.

According to Gibeaus´ findings in 1996 a minimal habitat patch of 4,5km² with a minimum width of 1,2 km represents a minimum-security area for female grizzly bears.

Primary or multi-species corridors

These corridors are designed to be used by a wide variety of wildlife species including carnivores (wolves, bears, cougar etc.) that are more wary of human activities and less inclined to venture close to settled areas. These are the main corridors connecting large contiguous areas.

Secondary corridors

These corridors are believed to be more appropriate for smaller wildlife species or species more readily acclimated to human activities and development.

Core areas and multiple use zones

The following graph (figure 2) shows a possible design for a multiple use zone:

illustration not visible in this excerpt

Figure 2. Possible design for a wildlife corridor network


When designing a reserve with interconnecting corridors, it is essential to have as little human disturbance as possible (Start 1991).

The core area of one habitat, where human activity is prohibited to ensure maintenance of wildlife habitat, is connected to the core area of another habitat via a corridor that contains enough native resources to temporarily sustain migrating animals. In core reserves ecological needs should have primacy.

The entire strip of interconnected land should be surrounded by a buffer zone that reduces adverse impacts of adjacent land uses. In areas buffering core reserves ecological, social, and economic values will be balanced.

The layer beyond the buffer zone is land primarily human-oriented, and only human-tolerant wildlife species can be found.


[1] In 1991, the prairie population of the grizzly was added to the list of species extirpated in Canada by COSEWIC (Environmental Protection 1997).

[2] Area excluding national parks

[3] Note: Grizzly bear numbers are very conservative. Due to low population densities, winter inactivity and poor sightability, assessing the population status and trend of grizzly bears is very difficult.

[4] Kananaskis Country is a multiple use area containing several parks and protected areas.

[5] Def.: Any species believed to be at risk. These species require a detailed assessment for possible formal designation as endangered or vulnerable (Kansas 2002).

[6] Def.: A taxon is vulnerable when it is not critically endangered or endangered but it is facing a high risk of extinction in the wild in the medium term future (The 2000 IUCN Red List of threatened Species 1994).

[7] Note: Now abbreviated with BVEAG

Excerpt out of 94 pages


Wildlife corridors and their effects on brown bears (Ursus arctos): a survey of Alberta citizens on knowledge and attitudes
University of Vienna  (Institute for Ecology)
2 (B)
Catalog Number
ISBN (eBook)
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1579 KB
Wildlife, Alberta
Quote paper
Maria Wechselberger, Mag. (Author), 2002, Wildlife corridors and their effects on brown bears (Ursus arctos): a survey of Alberta citizens on knowledge and attitudes, Munich, GRIN Verlag, https://www.grin.com/document/16056


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