MOOSE DENSITY AND COMPOSITION IN THE PARSNIP RIVER WATERSHED, BRITISH COLUMBIA, DECEMBER 2005. ANDREW B. D. WALKER, 5657 Simon Fraser Ave., Prince George, B.C., Canada, V2N 2C4 DOUGLAS C. HEARD, British Columbia Ministry of Environment, 4051 – 18th Ave., Prince George, B.C., Canada, V2N 1B3 VOLKER MICHELFELDER, British Columbia Ministry of Environment, 4051 – 18th Ave., Prince George, B.C., Canada, V2N 1B3 GLEN S. WATTS, British Columbia Ministry of Environment, 4051 – 18th Ave., Prince George, B.C., Canada, V2N 1B3 2006 Final report for the Ministry of Environment. Project No. 2914568 ABSTRACT In order to better understand the effects of hunting, changing landscapes, new management programs and predator-prey relationships involving moose in the Parsnip River watershed, we carried out a stratified random block survey in December 2005 (Gasaway et al. 1986). The early winter use of forest cover types by moose in the Parsnip River study area was used to delineate 2 strata. Estimates of moose numbers were determined by incorporating sightability bias from vegetation cover around each moose. Our total population estimate for the 2,501 km2 area was 3,000 ± 440 moose ( x ± SE). We counted 270 moose in 41 sample units (SUs) and surveyed a total of 181 km2. We observed an overall density of 1.18 moose/km2. The number of bulls per 100 cows was only slightly greater for the observed ratio than what was estimated after correcting for sightability (63 ± 10.9 bulls per 100 cows versus 59 ± 10.6 bulls per 100 cows, respectively), while the average number of calves per 100 cows was slightly lower for observed (26 ± 5.1 moose) than estimated ratios (30 ± 7.1 moose). We believe the moose population in the Parsnip River has changed little since the previous estimate of 2,600 ± 600 moose in 1998, which used a similar sampling and statistical design. ii TABLE OF CONTENTS Table of Contents .............................................................................................................ii List of Tables ................................................................................................................... iii List of Figures..................................................................................................................iv Introduction...................................................................................................................... 1 Study area ....................................................................................................................... 1 Methods........................................................................................................................... 2 Sampling Strategy........................................................................................................ 2 Data Analysis ............................................................................................................... 4 Results ............................................................................................................................ 5 Search effort and conditions ........................................................................................ 5 Population size and density ......................................................................................... 5 Composition ................................................................................................................. 5 Distribution ................................................................................................................... 6 Discussion ....................................................................................................................... 6 Census methods .......................................................................................................... 6 Population size, composition and distribution .............................................................. 8 Acknowledgements ....................................................................................................... 10 Literature Cited .............................................................................................................. 10 Appendix A. Itinerary and personnel involved in the Parsnip River moose census, December 2005. ......................................................................................................... 18 Appendix B. Moose observations, vegetation cover, snow depth and search effort in each sample unit during the Parsnip River moose census, December 2005. ............. 19 iii LIST OF TABLES Table 1. Vegetation cover classes, range of vegetation cover (%), detection probability and sightability correction factor, that was used to extrapolate population estimates of moose in the Parsnip River watershed, December 2005 (adapted from Heard et al. 1999a; Quayle et al. 2001).......................................................................................... 15 Table 2. Observed and estimated number of moose by stratum in the Parsnip River watershed (December 2005). ..................................................................................... 16 Table 3. The number and percentage of groups by vegetation cover class and mean vegetation cover ( x ± SE) that bull moose, barren cows without calves and maternal cows were observed using in the Parsnip River study area, December 2005. Sample size (n) indicates the number of groups in each vegetation cover class. The amount of vegetation cover did not differ among groups (F2, 170 = 1.52, P = 0.221) using a one- way analysis of variance (ANOVA). ............................................................................ 17 iv LIST OF FIGURES Fig. 1. The delineation of sample units, distribution of high density moose stratum (stratum 1) and study area boundary of the Parsnip River moose inventory, December 2005............................................................................................................................13 Fig. 2. The randomly selected sample units that were surveyed during the Parsnip River moose inventory, December 2005. ............................................................................. 14 1 INTRODUCTION Moose (Alces alces) are the most abundant big game animal in the Omineca region of northern British Columbia. They are hunted by First Nation and licensed hunters for sustenance and trophies. In order to better understand the effects of hunting, changing landscapes, new management programs and predator-prey relationships, estimates on the rate of population change are crucial (Gasaway et al. 1986). For these reasons we carried out a stratified random block survey (Gasaway et al. 1986) in December 2005 to estimate the population and composition of moose wintering in the Parsnip River watershed. We interpreted the results in relation to previous estimates from the Parsnip and Omineca regions in order to determine population trends that will aid future management decisions. The previous population was estimated at 1,400 ± 600 ( x ± 90 % CI) moose based on counts within 95 randomly selected survey plots (Heard et al. 1999a). However, using Anderson and Lindzey’s (1996) relationship between sightability and vegetation cover, the population was estimated at 2,600 ± 1000 moose. Calf recruitment was low at 23 ± 5.3 calves per 100 cows ( x ± SE) and sex ratio was high (112 ± 22 bulls per 100 cows). Quayle et al. (2001) followed Anderson and Lindzey’s (1996) approach to quantify moose numbers, using sightability data from moose in British Columbia. This model was subsequently adapted and included moose sightability data from the Ingenika River. Following this approach we believe population and composition estimates should be similar to those documented by Heard et al.’s (1999a) Anderson and Lindzey (1996) estimate, considering the lack of regulation changes regarding the harvest of moose or their predators. STUDY AREA The Parsnip River drainage falls within the Omineca region and Ministry of Environment’s wildlife management units 7-16 and 7-23 (Fig.1). The study area covered 2,501 km2 and was delineated by the 1200 m contour line to the east, the headwaters of 2 the Parsnip River to the south and the height of land between the Parsnip and Crooked River watershed to the west. The northern border runs south of Kenny Siding from the 1200 m contour and west along the CN rail line to highway 97. Radio-collared moose along the Parsnip River never traveled outside of these extents during previous years (D. Heard, unpubl. data). The area consists primarily of the wet cool variant of the sub-boreal spruce (SBSwk1) biogeoclimatic zone with some wet cool variant of the Engelmann spruce subalpine fir (ESSFwk2) and the very wet cool variant of the sub-boreal spruce (SBS vk) zones (Meidinger and Pojar 1991). The SBS contains hybrid white-Engelmann spruce (Picea glauca × engelmanni) and subalpine fir (Abies lasiocarpa) with extensive successional stands of lodgepole pine (Pinus contorta) and trembling aspen (Populus tremuloides) caused by recurrent disturbances. Occurring at higher elevations, the ESSF is dominated by Engelmann spruce and subalpine fir with lodgepole pine widespread throughout as the seral species. Mean annual precipitation ranges from 42 - 1700 cm, with 25 - 50 % as snow. An average annual temperature of 2.5 °C is typical for these biogeoclimatic zones. Snow persists from November through April with precipitation evenly distributed throughout the year (Meidinger and Pojar 1991). METHODS Sampling Strategy We divided the study area