Important wildlife habitat was destroyed as a result of hydroelectric development on the Bridge River system. Especially moose winter range together with grizzly and black bear spring habitat were affected. Moose need the lower elevation habitats to flee the restrictive snow depths and to find more forage during winter. These lost winter ranges need to be replaced or restored in order to regain historical moose populations.
Background of the Project
The overall objective of this project was to evaluate the current quantity and quality of winter range around the Carpenter and Downton reservoirs, determine if there are opportunities to enhance existing habitats or create new ranges near the affected areas and assess the current wintering moose populations.
Methods, Material and Study Area
The study was conducted in the Bridge River system around the Carpenter and Downton reservoirs. Historical and currently-used moose winter ranges were identified and assessed within the study area. This assessment was based on winter ranges that were mapped by the Ministry of Environment, Lands and Parks’ (MELP) Wildlife Section under the Lillooet Land and Resource Management Plan. When a site was determined suitable for possible enhancement the flight maps were transferred to 1:20,000 scale forest cover maps. For each of the enhancement areas attributes were evaluated including vegetation species composition, stand history, stand age, biogeoclimatic zone and subzone classifications. Due to a delayed project start the health of the herd and the density could not be assessed during the survey flights. The Bridge River’s original course was determined using Geographic Information System (GIS) mapping technology. With this knowledge the loss of winter range could be calculated. Together with expected moose density and the First Nations’ historical knowledge of moose numbers the populations that inhabited the Carpenter and Downton winter range before the reservoirs were determined. The value of non-resident and resident hunting per animal and the expected annual bull harvest were used to evaluate the unrealized economic value of the moose.
Results of the Study
There were three aerial surveys on March 1st, April 18th and May 4th which lasted 11.5 hours in total. The most important historical moose winter range is the Hurley River valley. This area shows unique climatic features such as heavy winter snowfall which means that the riparian areas in the lower elevations are significant to the moose. The forage in the adjacent riparian community is necessary for winter survival. Other winter ranges that show good quality for moose are the Gwyneth Lake cut-block and the similar Ferguson Creek cut-block. There are several other already existing moose winter ranges that were examined during the aerial surveys.
Potential winter ranges include the Liza Lake area, East Downton Lake, Tyaughton Lake, McDonald Creek, Mead Lake, Cadwallader Creek and West Downton Lake.
The creation of Carpenter and Downton Lake resulted in the loss of about 30 km2 of high quality riparian habitat. This habitat could have potentially supported 200-500 wintering moose. The total economic value of moose per year would have been about $11,385-$29,095.
Existing and potential moose winter ranges must be protected and if possible enhanced. When suitable cover and forage values are present in an area it is critical to minimize the intensity of open roads. Juvenile spacing and pruning can increase browse production. Another method to enhance the moose winter ranges is prescribed burning. The burning will enhance browse growth for the moose.
Due to the Carpenter and Downton reservoirs moose lost a lot of their winter range in the Bridge River system. To protect, maintain and enhance still existing moose winter habitats it is important to address the issues of cover, forage and access management. To stimulate browse production methods such as prescribed burning and juvenile spacing and pruning can be used. Access management is another important strategy to reduce disturbance and over-hunting.
- Source S. L. Lemke. June 2000. Moose Winter Habitat Evaluation and Enhancement Opportunities in the Bridge River System. Prepared by Ursus Ecological Consulting, for B.C. Hydro, Bridge/Coastal Compensation Program and the Ministry of Environment, Lands and Parks. 24 p. Available at : https://a100.gov.bc.ca/pub/acat/documents/r41078/99W03_moose_1389800932262_9800450116.pdf [Accessed 03/2021].