2007-08-012-C11 - Assessing possible impacts of increasing use of off-road vehicles on the Dall’s sheep population and their habitat on Pilot Mountain (Miners Range); LRRC
Summary
The Laberge Renewable Resources Council, in partnership with the Ta’an Kwach’an Council and Environment Yukon, and with funding support from the Yukon Fish and Wildlife Enhancement Trust Fund, undertook studies on the potential impacts of human activity on Sheep and other wildlife in the Miners range (Pilot Mountain, Flat Mountain) in South Central Yukon. This range of mountains (GMS 5-50) is situated to the West of the City of Whitehorse and is bounded by access routes including the North Klondike Highway, the Takhini River Road and the Dawson Trail. Therefore the mountain block has been accessible for many decades. Concern over the growing use of Off-Road Vehicles (ORV’s) including 4 wheelers and snowmobiles (Loeks 2000) resulted in this range being identified as a possible test case to assess the potential for adverse effects from the use of these vehicles for recreation and hunting of a small local sheep population. This report documents current status of the sheep population and the studies conducted in 2007/2008 for this area. Overall, the three partners contributed a total of $27,600 to the $12,000 funding support from the Fish and Wildlife Enhancement Trust Fund. With the exception of the ORV trail monitoring, not completed due to equipment problems, the balance of the studies were accomplished as per the proposal outline.
A reconnaissance of the trails and sheep on Pilot Mountain were flown by helicopter on July 14, 2007. The purpose of this survey was to document existing trails, assess possible camp locations for a future ground based assessment and to evaluate sheep distribution and numbers over the range and within easy observation distance for the proposed ground camp. A number of trails were identified in the Pilot Mountain range and a camp location identified at the terminus of one ATV trail. This flight has also documented locations of 175 sheep including 32 rams, 117 ewes and 26 lambs. This count was within historical survey results from surveys dating back to the 1970’s.
A ground reconnaissance was conducted between July 28th and August 6th. A crew of three personnel used ATVs to access the main sheep range in central Pilot Mountain to evaluate sheep behaviour and distribution relative to one access route. A second crew arrived with a supply flight into the camp. Observations were made on the distribution and composition of the sheep groups accessed from a central camp and from daily hikes into the surrounding alpine areas. The best total count of the range from an earlier aerial survey was 175 sheep. Repeated observations of a subset of these sheep from the ground resulted in classification of 68% nursery sheep, 12 % lambs, and 19 % rams. It is noteworthy that of the rams classified, only 5% or three animals equaled or exceeded the legal hunting size according to the YTG hunting regulations. Behavioural observations on 12 different groups for 19 hours over four days found that sheep spent 32 % of their time bedded, 30 % feeding, 19 % walking and 19 % looking. There were too few human encounters to assess whether human activity altered these behaviours.
Local knowledge was gathered through a public open house held in the Hootalinqua Fire Hall on October 25, 2007. This was followed by a series of person to person local knowledge interviews. Information provided by the public with experience in this area was gathered as both written interviews and as mapped polygons. A dozen residents contributed information directly onto maps at the open house and 38 of an additional 50 contacted agreed to be interviewed. An additional six people were approached for specific information, when this report was written. We surveyed a representative cross section of opinions including pilots, outfitters, guides, hunters, trappers, wilderness guides, hinterland hikers, and people hunting with horses, and residents who watch and feed birds or note wildlife sightings when commuting to work. This represented a significant sample considering that GMZ 5-50 is a very small area of the Yukon. The product of these surveys were tabulated and mapped. Recommendations from the public were also included in the final report.
Sheep historical use and ecology was assessed based on local knowledge, data in Environment Yukon sheep harvest management files. Between 1975 and 2007, twelve separate sheep surveys have been carried out, though fewer occurred in the later years. The average estimated population has been about 150 sheep and currently estimated to be at least 175 sheep. Concern is expressed over the low count of rams and their under-representation relative to nursery sheep. Current levels are estimated 27.4% with the longer term historical levels nearer 30%. These are contrasted with other populations were ratios range between 49 and 66 rams per 100 nursery sheep. Sheep habitat use, distribution, horn growth and hunting history are reviewed.
Recommendations include correction of the skewed ratio through limiting pressure on existing legal sheep, repeated sheep survey in 2008 and an evaluation of key habitat use by these sheep.
To download a copy of the report, click here: Assessing possible impacts of increasing use of off-road vehicles on the Dall’s sheep population and their habitat on Pilot Mountain (Miners Range) (pdf).
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