Ungulate

Recommended method(s): Stratified random block counts with correction for sightability. Research into appropriate survey methods for estimating absolute abundance of Roosevelt elk is still required.

Rocky Mountain elk are found mainly in southeast (Southern Interior Mountains; MS, IDF, PP) and northeast (Northern Boreal Mountains; SWB, BWBS) British Columbia. Smaller populations occur in the Okanagan Region and near Lytton (Southern Interior ecoprovince; IDF, PP). Roosevelt elk are restricted to Vancouver Island and the Sunshine Coast (Georgia Depression ecoprovince, Eastern and Western Vancouver Island ecoregions; CWH, CDF)).

4.5.1 Survey methods

Stratified random block counts are recommended for elk surveys except on Vancouver Island. Roosevelt elk will require mark-resight estimators because of low sightability in coastal forests. The elk survey methodology described by Unsworth et al. (1994 has been used in the East Kootenay (Southern Rocky Mountain Trench ecoregion; IDF, PP, MS; Simpson 1992a, 1992b), and may be appropriate for northeast British Columbia (Northern Boreal Mountains, Boreal Plains; BWBS, SWB). In the latter are, the Gasaway moose survey methodology has been applied to elk, but with smaller black sizes, and also appears to provide suitable estimates of survey precision. Low sightability may limit the effectiveness of sightability models in the ICH zone (Columbia Mountains and Highlands ecoregion), although sightability trials are underway in Idaho within ICH forest types (Dave Leptich, pers. comm.).

4.5.2 Defining search areas and stratification

Elk are contagiously distributed in winter. Snow depth and condition are thought to determine elk distribution primarily by limiting forage. Heavy snowfall will restrict animals to low elevations. Deep snow facilitates surveys, and the highest population counts have been obtained in severe winters (Samuel 1984). Use of grassland areas is not restricted by 20 cm new fresh snow, but with crusting or depths of 30 cm or more, elk will move into shrub and conifer dominated habitats. Depths of more than 60 cm restrict mobility, and elk will move to lower elevation forested habitats. Crusting in late winter restricts use of grassland by elk to periods when solar radiation softens the snow (Peck and Peek 1991).

Distinctive ridge-tops or large rivers should be used as block or sample unit boundaries. If a survey area is flat, roads or fence lines may be used as sample unit boundaries.

Sample units of 8 to 16 km 2 in size are good for timbered or partially timbered habitats. Open habitats (sagebrush and grass) can be 30 to 50 km 2 because they can be surveyed rapidly. Low density strata units should be kept small (10 to 15 km 2), and high density units larger (30 to 50 km 2), so large wandering groups of elk will not be missed. Sample units should require about one hour of helicopter survey time.

Based on previous knowledge of their study area, Unsworth et al. (1994) stratified blocks with expected numbers of elk as 0 to 35 (low), 36 to 85 (medium) and 86+ (high). A pre-survey flight is required for accurate stratification. If there is little information, Unsworth et al. (1994) recommend two levels (0 to 50 and 50+) for the first surveys in an area. All ranges, except those of extremely low potential, should be included. In some cases, islands of suitable habitat exist due to favourable aspect or vegetation. Include those areas and rate surrounding areas as nil.

As for moose, surveys should immediately follow stratification. Elk movements in that time can easily affect the accuracy of stratification and thus the population estimate.

4.5.3 Survey timing

The best time to survey elk is when snow conditions, and cold, force animals onto the lowest portions of their winter range, usually in January or February, before the antlers are dropped. Search areas are then much reduced in size. Green vegetation in spring concentrates larger groups. However, in spring, snow does not restrict movement, and entire sub-units at high elevation must be surveyed. Antler drop will affect composition estimates in spring surveys (Unsworth et al. 1994).

4.5.4 In-flight survey procedures

Blocks are surveyed entirely by flying overlapping transects on flat ground, or contours in steep terrain. When block counts are done in mountainous regions, flying contours at 90 m intervals in dense cover, and at 150 m intervals in areas with more open cover may be appropriate. Above canopy altitude should be 30 to 45 m along the contour center line. Fly at a ground speed of 65 to 80 km/h. Canyons should be flown 30 m higher than the contour line, dropping to the original contour when leaving, to avoid missing canyon bottom areas (Unsworth et al. 1994). Terrain and timing differences are the main differences of in-flight procedures for elk and moose.

When a group of elk is sighted, it should be circled to ensure that all animals are seen. The group may be moved slowly to an area which has already been surveyed. Total group size should be determined first, calves and bulls can be counted individually and remaining animals are classed as cows, although some will be female yearlings.

4.5.5 Classification

Bull elk often occupy peripheral and denser habitats than cows, and occur in smaller groups. Bulls are, therefore, more frequently missed during aerial counts and bull:cow ratios are often underestimated (Samuel 1984). Sampling in all strata, and using estimates corrected for sightability biases, will provide the most accurate population composition estimates.

Elk are easily classified because males retain their antlers through February. Females are antlerless. Yearling females cannot be reliably distinguished from older cows. Level 1 should be used for reconnaissance after antler drop; Level 2 for early winter reconnaissance; and Level 3 for composition and population inventory. Table 7 shows sex/age classification characteristics. Classification of large groups may be difficult. Sub-sampling large groups should be avoided. A sub-sample approach may yield misleading results which deviate from the true group composition (Unsworth et al. 1994).

4.5.6 Estimating numbers missed

Unsworth et al. (1994) consider group size, percent vegetative cover and snow cover as the most important factors influencing elk sightability. Flying surveys in open habitat with extensive snow cover, when group sizes are large, results in the most accurate population estimates.

Currently, the Idaho elk sightability model is not recommended for use for Rocky Mountain elk in British Columbia, until more sightability trials have been conducted, and the influence of using Jet Ranger (Bell 206) aircraft have been evaluated. Nonetheless, it would be prudent to begin to record group size, percent vegetative cover and percent snow cover so that survey estimates may be corrected at a later date, when the sightability trials have validated the model for B.C. conditions. Methods for estimating those variables are given in Unsworth et al. (1994). Roosevelt elk will almost certainly require use of mark-resight estimators to correct for missing animals.

Published by the Resources Inventory Committee

[Back to TOC] [Previous] [Next]