Towards Integrated Management solutions: The Itcha-Ilgachuz Caribou Project Radio-Telemetry Year 3 progress report
(1995-98)
By James A. Young and Kerra L. Shaw, November 1998

The Cariboo-Chilcotin Land Use Plan (CCLUP) requires the development of a caribou (Rangifer tarandus caribou) strategy for the Itcha-Ilgachuz caribou that maintains winter range habitat values and provides integrated management approaches to habitat management. One component of the information base that will be utilised to develop this strategy is the collection of conventional radio-telemetry data from radio-collared caribou. This progress report summarizes habitat use information collected from 34 radio-collared female caribou from October 1995 until May 1998. Monitoring of radio-collared caribou will continue until at least the end of the 1999-00 winter.

There were two different wintering strategies observed in this population. A majority of caribou in the three years of monitoring wintered in low elevation forested areas for the duration of the winter. These winter forest-dwelling caribou were further divided into two herds; the Itcha-Ilgachuz Mountains herd and the Rainbow Mountains herd based on the geographical areas where individual caribou calved. Individual home ranges showed common movement by caribou between the Itcha and Ilgachuz Mountains (the Itcha-Ilgachuz Mountains herd) and the Rainbow and Ilgachuz Mountains (the Rainbow Mountains herd), but there was little movement between the further separated Itcha and Rainbow Mountains. During the winter of 1995-96, approximately 10% of the caribou population, including the majority of the Rainbow Mountains herd, wintered on windswept, alpine ridges on the north side of both the Itcha and Ilgachuz Mountains. Only one radio-collared caribou employed the same strategy in the winter of 1997-98, and was thus considered a winter alpine-dwelling caribou.

The Itcha-Ilgachuz Mountains herd calved and then spent the summer (June-August) and early fall (September and October) near the treeline within the Itcha-Ilgachuz Provincial Park. In the late fall (November) and early winter (December to mid-January), caribou descended to lower elevations within the Montane Spruce biogeoclimatic zone, where they primarily utilised fescue meadows and mature open pine forests containing terrestrial lichens. As snow depths increased and winter progressed, caribou appeared to prefer pine stands that were either on dry or wet sites. When in forested areas, caribou utilised mature, moderately closed pine stands on poor quality sites and relatively flat terrain, between 1200-1600 meters in elevation. The majority of radio-collared animals were dispersed over a large area in the winter, utilising pine stands north, east, and south of the Itcha Mountains. In spring (May), caribou began migrating back towards their calving grounds within the Itcha and Ilgachuz Mountains, following the receding snowline.

The Rainbow Mountains herd calved throughout the Rainbow Mountains in the alpine. They spent the rest of the summer and early fall on the relatively steep alpine areas within Tweedsmuir Park before descending in the late fall into the Sub-Boreal Pine/Spruce for the winter. Throughout the winter, these radio-collared caribou were found in flat, low elevation mature pine or pine/spruce stands. They were observed to winter in the Dean River valley between Anahim Lake and Anahim Peak, before again returning to the alpine to calve in the spring.

The portion of the caribou population that was winter alpine-dwelling was found on high elevation windswept ridges within the Itcha and Ilgachuz Mountains where cratering for terrestrial lichens was possible. These alpine habitats were of relatively gentle slopes and supported caribou through the mid-winter, late winter/early spring and spring seasons. During the summer and fall, these caribou lived in similar areas to where the winter forest-dwelling caribou resided, thus summer and fall habitat use information was pooled with other data from their respective herds.

Caribou summer and winter range were often separate and distinct areas. Most caribou appeared to spend the winter within a discrete area but did not necessarily return to the same area the following winter.

 ACKNOWLEDGMENTS

Funding for the first year of this project was provided by the Corporate Resource Inventory Initiative (CRII), and the second and third years by Forest Renewal British Columbia (FRBC). Direction for this project has been provided by the regional Caribou Strategy Committee as directed by the Cariboo-Chilcotin Land Use Plan.

Caribou capture work was skilfully completed by net gunners Pat Dielman and Doug Jury and helicopter pilots Tom Arduini and Wade Ross. Lara Webster and Chris Schmid assisted in the capture work. Fixed wing telemetry flights were safely piloted by Floyd Vaughan, Wayne Escott, Paul Hindle, Anton Forster, Ben Davidson, and Al Yard. Stefan Himmer, Kerra Shaw, Jim Young, Lara Webster, Val Young, and Steve Richberg collected the habitat information for the telemetry flights. John Youds reviewed a previous draft of this report. Jennifer Ballentine of the B.C. Environment GIS section produced Figures 1-2 and 4-7, all home range maps, and aided in the organisation of BEC units and CCLUP subunit data. Karen Samuelson and Jennifer Ballentine generated all of the habitat use data (excluding caribou habitat data) from computer coverages utilising telemetry flight location information. We thank all of the above for their contributions to this project.