EASTERN SLOPES GRIZZLY BEAR PROJECT (ESGBP):
BRIEF UPDATE,
APRIL 2003.
Stephen Herrero, University of Calgary, Calgary
Michael L. Gibeau, Banff National Park, Lake Louise
Saundi Stevens, University of Calgary, Calgary
Bryon Benn, AXYS Consulting, Calgary
Interagency, multi-stakeholder sponsored research on grizzly bears in the
Central Rockies Ecosystem (CRE) began in 1994 as part of the Eastern
Slopes Grizzly Bear Project. Most research has focused on the portion of
the CRE defined by the Bow River Watershed in Alberta and encompassing
major portions of Banff National Park and Kananaskis Country. This
geographic focus has primarily reflected funding, not ecology. As part of
the research we captured, radio-tagged and monitored 37 female and 34 male
bears. Individual bears have been monitored for up to 9 years. By
November, 2002, we had collected 9 years of data. Seven Master’s and Ph.D.
theses and a body of scientific and management publications have been
completed (www.canadianrockies.net/Grizzly). The field component of the
integrated research is completed and we are preparing additional research
papers and a final report.
Demographic analysis, lead by Dave Garshelis, has been based on monitoring
life history parameters of the radio-tagged grizzly bears. We accumulated
143 bear-years of reproductive information on adult-aged female grizzly
bears and were able to back-fill another 12 bear-years. Reproduction was
characterized by late age of first reproduction, small litter size, long
interlitter intervals and one of the lowest reproductive rates found for a
grizzly bear population in North America. Survival rates for adult females
were high, between 95-96%. We attribute this high survival of adult
females to focused and extended effort by managers to keep individual
females alive despite conflict with human use. The high adult female
survival supported a high probability of positive population growth
(lambda) despite the low reproductive output. This positive trajectory is
tenuous because it requires continuing success in keeping individual
female grizzly bears alive even though many are habituated and prone to
conflict with people. The apparent low density of the population also
makes Bow River Watershed grizzly bears potentially subject to rapid
decline with small increases in female mortality.
Those responsible for grizzly bear management in the Alberta, British
Columbia and national park portions of the CRE agree with the goal of
maintaining a non-declining grizzly bear population. This will become
increasingly more challenging because grizzly bears in the Alberta portion
of the CRE, including Banff National Park, live in one of the most
developed landscapes in North America where the species still survives.
Adding to the challenge of maintaining grizzly bears, grizzly bear habitat
in the CRE is naturally fragmented by rock and ice. Extensive linear
developments such as highways, roads and railways follow valley bottoms
and further fragment and stress grizzly bear habitat and populations. A
large and rapidly growing human population in Calgary (about 900,000) and
surround intensively use linear corridors, developed sites and backcountry
areas in grizzly bear habitat. Recreation and natural resource use and
development are primary land uses. In addition to our population research
the ESGBP has focused on detailing the nature of fragmentation and
human-caused mortalities.
Secure habitat is where grizzly bears have a low probability of
encountering people. In secure habitat grizzly bears can feed with little
human-caused disturbance and maintain their wary behaviour. The CRE has
had extensive and continuous loss of secure habitat for many decades, even
inside of protected areas such as Banff National Park. This has primarily
been due to fragmentation caused by access and other development
encouraging widespread human use. Most recent results show that in the CRE,
British Columbia lands, at 50%, had the largest percentage of secure
habitat, Alberta provincial lands and national parks both had 43% and
Kananaskis Country had 36%. The US Forest Service target for secure
grizzly bear habitat is 68%. Percentage of secure habitat that is also
high quality was low ranging from 13% in BC provincial lands to 5% in the
national park portions of the CRE.
627 of 639 known grizzly bear mortalities in the CRE, 1971 – 1996, were
human-caused. Eighty-five percent of 462 of these, where location could be
accurately determined, were within 500 m of a road or 200 m of a trail.
Area concentrated mortalities, correlated with access and human use, were
found in Alberta near Banff townsite, Lake Louise, the Red Deer River, and
in BC in the Elk and Blaeberry Valleys. Of particular concern, in Banff
National Park, 1985 – 1998, female grizzly bears made up 80% of
human-caused mortalities.
It is encouraging that the protected population of grizzly bears that were
trapped and studied during our research in the Bow River watershed had
positive population growth. However, this will be difficult to maintain
because of the cumulative effects of the expanding human population and
development. To sustain grizzly bears in the CRE at current levels will
require integrated management by Alberta, British Columbia and the
national parks as these jurisdictions share management of grizzly bear
habitat in the CRE. Target values for population, landscape and
behavioural conditions will need to be set and achieved within a landscape
where many human interests overlap and compete with the needs of grizzly
bears.
|
IN ESPAÑOL!
IN DEUTSCH!
IN ENGLISH!
