Introduction
The largest land predator in British Columbia is the Grizzly Bear. On a global scale the species has been wiped out from over 50% of its territory. Grizzly Bears can still be found in Canada, the USA and about 42 Eurasian countries.They are slow to reproduce and therefore occur at a low density. The Grizzly Bear is a BC Conservation Data Center blue-listed species. Out of 56 identified Grizzly Bear Population Units, 47 are stable and nine are jeopardized. To regain populations, management actions include but are not limited to the reduction of interactions between bears and humans, identification of critical foraging habitat followed by management of those areas and maintenance of important connectivity corridors.
Background of the Research Project
Overall, the goals were to locate, assess and map Grizzly Bear habitats throughout the year, verify berry production areas, recommend a classification for habitat management, raise more awareness and build an opportunity for the development of their quantity. The evaluation of important bear foraging areas will be used to realize conservation and management actions. Through conservation of Grizzly Bear habitat the populations can recover again.
Methods, Materials and Study Area
The Cascades Forest District in the Lillooet Timber Supply Area is the study area used for this research. The area continues north along the Fraser to French Bar from its eastern edge. It also extends west to include the Kwoiek, Stein, Cayoosh, Seton and Carpenter River watersheds. The study area is within two eco-regions. One is the Interior Transition and the other one Chilcotin. The Interior Transition encompasses parts of the southern Pacific Ranges which has a collection of different climates. The Chilcotin region is set within a rain shadow.
In April 2011 project participants met in Kamloops to further advanced project planning, go through existing Grizzly Bear projects and to organize and adjust expertise connected to Grizzly Bear habitat management. The next step was the spring habitat assessment which started with the modeling of the habitat. This was used to predict the distribution and abundance of Grizzly Bear foraging habitats in spring within the Lillooet TSA. Then followed the ground assessment of the spring habitat. A list of important foraging habitat was composed. The ground assessments took place in June and July. Different systems of measurements were used including the methods from the DEITF Manual and bear site-use investigation forms used in previous years. The different areas were traveled through to determine forage quality, distribution and abundance to apply a field rank to each area. Bear activity including Grizzly Bear and American Black Bear were assessed by recording proof of such activities as rubbing trees, digging and grazing. The quality ranks that were given to each section were used to describe importance of that area as bear spring foraging habitat. The ranks were then used to prioritize the conservation of each spring foraging habitat. Aerial assessment was an alternative method used for a more rapid field verification of spring-habitat. Areas where the aerial survey was conducted were chosen based on habitat risk, quality and difficulty of ground access. For example areas that were remote were rather chosen for aerial surveys.
Another important habitat for the Grizzly Bear is the Whitebark Pine foraging habitat. For each watershed in the area GIS-based modeling was used to map the Whitebark Pine habitats. The aerial assessment of this area followed. The ground assessment was conducted using the “Relevé” sample design, a method that is cost efficient though not quite as statistically robust as other approaches. This design uses the belt-transact procedure to collect data on forest health and structure. Samplings were carried out between July and mid-September in both 2011 and 2012.
The last important bear foraging habitat assessed was the huckleberry (Vaccinium membranaceum) habitat. At the beginning each habitat sampled was classified as one of the following: the “Suitable” berry habitats that are presently supporting a healthy shrub component of huckleberry and the “Capable” berry habitats where a suppressed component of huckleberry is being supported. Due to the large size of the project area a non-random sample design was chosen in 2011. This allowed focus to be on the suitable berry habitats and habitats that were easily accessible. On ground trucks and ATVs were used to access most of the sites. If too remote work continued with a helicopter. A paired transect approach was used: for each evaluation of a suitable habitat there was also a paired assessment in an adjoining capable berry habitat. In 2012 the method of sampling was adjusted by taking up a 100m drop-line transect method. Technicians would evaluate the wealth of berry producing plants by walking a 100m transect and calculating vegetation directly below the tape. In the end each area was given a field ranking of High, Medium, Low or Nil derived from from huckleberry abundance, prosperity of other berry producing plants and bear use.
Data analysis was completed in R-Studio. All field ranks were compared to the model ranks to figure out the accuracy of the models. In year two Traditional Ecological Knowledge was also incorporated in the project.
Result of the Study
For the spring habitat almost 900,000 hectares of Lillooet TSA were mapped and evaluated. 214 areas were assessed on two flights within the South Chilcotin GBPU. During these aerial assessments 13 areas were ranked as High, 41 as Medium, 140 as Low and 20 as Nil. During the aerial assessments of the northeast watershed units 182 areas were ranked and identified. Of these, 49% were ranked as Low, 25% as Nil, 16% Wetland, 8% Medium and 2% Riparian. For the ground assessment 35 areas were completed in 2011 and 77 in 2012. Of these spring habitat areas 51 were identified as avalanche chutes, 43 as herbaceous meadows, two were a combination of both, ten areas were classified as wetland-shrubs and three as wetland. At the plant community level 30 sites were identified as tall shrubs , while 43 sites were determined as herbaceous meadow complexes, 16 sites were within low shrub communities, 19 were both tall shrubs and herb communities, six sites consisted of low shrub and herb communities and the final four sites combined all three categories.
During the aerial assessment of the Whitebark Pine habitats a total of 87 areas were evaluated. Two out of the 87 were pure Whitebark Pine stands and the rest were mixed stands. Through ground assessment a total of 153 areas were sampled. The results from this evaluation support already known information on the spatial distribution of Whitebark Pine.
For the huckleberry foraging habitat in 2011 67 transects of “Suitable” habitats and 45 transects of “Capable” habitats were completed. For the second year a total of 307 areas were sampled with the adjusted method. The huckleberry had the highest percent cover values in areas with north or northeast conditions.
To raise awareness and promote the grizzly Bear project a display was set up at the 2011 “Salmon in the Canyon” festival.
Discussion
There are two distinct scales of spring foraging habitat; the stand and landscape. The Stein-Nahatlatch has a lower Grizzly Bear population than the South Chilcotin areas, even though the Stein-Nahatlatch has about 0.8% more of open spring food cover than the South Chilcotin area. Therefore, the spring habitat is most likely not a limiting factor for the Grizzly Bears. In general, the results of the spring forage habitat assessment with GIS mapping proved an accurate understanding of most Grizzly Bear spring foraging habitats within the Lillooet TSA.
The aerial and ground based assessments in the Whitebark Pine areas that were completed confirmed various ecological relationships coherent with environmental conditions known to affect the Whitebark Pine distribution.
The wealth and distribution of Huckleberry at the stand and landscape level was associated with the moisture gradients.
Lastly, the incorporation of Traditional Ecological Knowledge might be important as the Grizzly Bear population recovery goals could be reached as a team.
Suggested Action
The Grizzly Bears’ ability to survive depends on its access to the seasonal foraging habitats. Therefore, it is important to take initiative in the conservation of important habitats within the Stein-Nahatlatch and South Chilcotin.
It is also important to keep the public educationally aware and monitor Grizzly Bear movements to lessen the mortality linked to human bear encounters.
Conclusion of Research
To not decrease the number of Grizzly Bear population it is important to protect and conserve the different seasonal foraging habitats. This research assessed the spring foraging, Whitebark Pine and the Huckleberry habitats. Educating and raising awareness is another critical component to ensure more safety associated to human bear encounters.
- Source Ministry of Environment. March 2013. Grizzly Bear Habitat Management in the Bridge River Restoration Area 2011 & 2012 Final Report. Available at : https://a100.gov.bc.ca/pub/acat/documents/r39454/12.W.BRG.02_1383599355107_b690768f8c695afcef84835ddff675e8fee5f7ddbf090cfa887a6b14fded49b9.pdf [Accessed 03/2021].