in the Canadian
Rockies
Bears and
Habitat
Bears and
Roads
Bears and
Science
Research Methods
and Technologies
Bears and Research in the Canadian Rockies
Studying bears and other large carnivores is expensive, and can require a time-frame of five years or longer. Piecing together an accurate picture of population characteristics, habitat use patterns, responses to changing environments etc. is a challenging task, made especially difficult because bears roam over very large areas and they are relatively long-lived. Therefore, the development and/or refinement of methods for accurate, efficient collection and analysis of field data are an important aspect of bear research.
Where
are the bears?
Knowing the
locations of bears is essential to
learning how they use habitat, move through their landscape, respond to
change or to human presence and activities, disperse etc. The following are
the main methods used to determine bear locations: Radio-telemetry, GPS technology, Other methods.
Radio-telemetry
This method involves capturing and immobilizing bears so that they
can be fitted with a radio-collar and/or ear-tag. Each collar or tag is
equipped with a transmitter and a battery. Each transmitter is set to broadcast
at a specific frequency in the same way that radio stations each broadcast
at a specific frequency. Researchers then use an antenna connected to
a radio receiver to pick up the signal transmitted by the collar or tag,
in the same way that we would tune our radio to pick up a
radio station. Accurate locations of radio-collared bears can be obtained
from the ground or from an airplane.
Global Positioning
Systems
Global Positioning
Systems (GPS) technology has only very recently been applied to locating
bears and tracking their movements. GPS technology employs a network
of satellites and a receiver to pinpoint exact geographic locations on
earth. Special bear collars equipped with GPS receivers log locations
based on the information received from the satellite
network. Researchers can set the collars to log a specific number of
locations per day, week, etc depending on the type of information they
need. Information can be retrieved from the collars either remotely
(using overflights to download data from the collars, or through remote
transmission to a computer database) or by retrieving the actual collar
itself. The Foothills Model Forest Grizzly Bear Research
Project
is employing this technology in their work.
Other methods
A variety of other methods are used
to document areas used by bears. For example, biologists make note of
bear scat, tracks, feeding signs (e.g., diggings, grazed vegetation, ripped
up logs and stumps) and rub-trees that they may observe in
the field. Biologists have also installed motion-detecting cameras in bear habitat
to attempt to document bear movements through an area. These cameras
are triggered to take a photo of a bear (or other animal) when it walks
through or “breaks” an infrared beam.
Counting
bears
Estimating the number of bears in a
population, and determining whether the population is increasing, decreasing
or remaining stable over time are the “million dollar questions” of
bear research, management and conservation. They are also among the most
challenging to answer.
How many bears are
there?
Determining the number of bears in a
population is an inexact science. Researchers employ a variety of
techniques, often in combination, as well as rely on their professional
judgement to derive estimates. For example, habitat-based approaches
involve:
-
estimating regional carrying capacity based on habitat quality
-
stepping down this number by taking into consideration land-use activities, hunting, human-bear conflicts, habitat loss etc.
(Ministry of Environment, Lands and Parks, British Columbia 1995)
Traditional mark-recapture methods to estimate bear populations are also very complicated because:
-
bears are not easily seen in forested habitat
-
large home ranges and low population densities make for small sample sizes
-
age and sex classes are difficult to determine without actually handling bears
-
mixing up grizzly and black bear sign is possible
-
individual bears have different “capture” probabilities
(Woods et al 1999 and Woods et al 1996)
Scientists with the West Slopes Bear Research Project have contributed significantly to this area of bear research by pioneering work on the use of DNA extracted from bear hair as the “mark” in successive rounds of mark-recapture sampling. The techniques they developed have many other applications to bear research including: presence-absence studies, population distribution, home range delineation, measuring genetic diversity within and between populations, family relationships, dispersal and genetic success of translocations. (Woods et al 1999) The technique has been/is being employed and refined in bear studies in Asia, Europe and North America. (Woods 2000)
Is the population increasing, decreasing
or remaining stable?
Calculating the intrinsic population growth
rate (“lambda”) requires long-term data collection of a given bear
population. The Eastern
Slopes Grizzly Bear Project (ESGBP) is aiming for 100 bear years of data,
translating into 7 or 8 years of data collection, before calculating
lambda. It is expected that this will happen sometime in
2001. (Hererro and Gibeau 1999)
The Flathead
Bear Study which has been ongoing since the late
1970s has calculated lambda for the regional grizzly bear
population. Their results showed a population increase rate for the
period 1979 – 1994 of 1.085±.026. (Hovey and McLellan
1996)
Because studies are often constrained by a lack of baseline data from the past and by short timelines, determining scientifically defensible population trends is not always possible. However, combined evidence from a variety of other data can sometimes suggest with fair confidence, the general population trends. In their report “Grizzly Bear Population and Habitat Status in Banff National Park”, researchers with the ESGBP recognized these constraints and went on to state that the combination of “mortality and translocation data, very limited grizzly bear use of Bear Management Unit #22, and high habitat fragmentation all present converging evidence that suggests grizzly bear population declines in the Bow River Valley.” 1
Putting
it all together
Geographic Information Systems (GIS)
are computer software programs that can integrate several “layers” of
information by overlaying them spatially. By integrating landscape
features with other factors in the bears’ world, GIS helps researchers to
better understand the relationships between variables, and to more
effectively communicate with land managers and the public. (Van Tighem 1997) For example, GIS-based habitat
effectiveness models incorporate physical landscape characteristics and
human-use information to produce maps that illustrate the actual ability
of the landscape to support grizzly bears. (Gibeau et al
1996)
Managers can use these
maps to identify areas where habitat effectiveness is at an acceptable level,
and areas where actions must be taken to improve it.