North Thompson Moose Distribution And Classification Surveys Winter 2005

Transcription

1 North Thompson Moose Distribution And Classification Surveys Winter 2005 Prepared for: British Columbia Conservation Foundation Surrey, BC August 2005 Prepared by: S. L. Lemke

2 North Thompson MooseClassification Surveys 2005 Summary Successful moose management depends on knowledge of local population distribution and structure and a reasonable estimate of population size; with this data in hand, wildlife managers can more confidently formulate sustainable moose harvest objectives and regulations. In its absence, managers are obliged to apply very conservative harvests to ensure herd sustainability. Since the late 1970s, very little moose population inventory work has been carried out in the North Thompson watershed. The absence of current, reliable moose inventory data prompted regional wildlife staff to seek and secure funding, through the Recreational Stewardship Inventory Fund, to complete a stratified random block moose survey in the North Thompson watershed. Due to extended periods of unsettled weather and poor snow conditions throughout January and February 2004 and again in early January 2005, a decision was made to apply project funding towards classified counts and winter distribution mapping. The objectives of the work were to 1) determine the age/sex composition of local moose populations on important winter ranges in the upper North Thompson watershed, 2) refine the extent of existing critical moose winter range mapping in the area and 3) re-evaluate current moose harvest objectives and regulations in several management units of the North Thompson moose management zone. A total of 18.5 hours was spent in searching for and classifying moose within known or expected high density moose winter habitats in the North Thompson management units. Four hundred and sixteen (416) moose were observed: 123 bulls, 207 cows, 71 calves and 17 unclassified adults. Twenty-nine percent (29%) of cows were attending calves. Overall, bull and calf ratios (59 bulls per 100 cows and 34 calves per 100 cows) were indicative of a productive, increasing population, and all animals observed were in good condition. Reduced calf survival in the Mud Creek drainage and in southern Wells Gray Park may be attributed to wolf predation: signs of wolf activity in these areas were observed during survey flights. High value moose winter ranges in the North Thompson zone are very obviously delineated; there appears to be little in the way of transition between high and low quality range. In more southern MUs, the topography lends itself to extensive areas of moderate value winter range between lower elevation, high quality riparian and wetland sites and higher elevation, snow limiting, timbered habitats of little winter value to moose. In the North Thompson, abrupt elevational changes reduce the area of this transitional habitat. We suspect there are pockets of suitable winter range that support significant numbers of moose, and there may be animals wintering on different habitat types than those classic moose winter ranges targeted by classification count surveys. Moose numbers in southern British Columbia have been increasing over the past decade. In the North Thompson zone, as in other areas, the increase has likely been stimulated by habitat changes brought about by timber harvesting and amplified by mortality and harvest rates inadequate to stem population growth. Based on observations from the 2005 surveys, an increase in the annual allowable harvest could be considered. ii

3 North Thompson MooseClassification Surveys 2005 Increasing cow and/or calf harvest could help regulate the growing moose population. These sustainable increases in harvest levels would provide additional, much sought-after opportunities to recreational hunters and may ultimately reduce moose numbers sufficiently to decrease wolf numbers and their impacts on the region s caribou population. To obtain estimates of absolute abundance, a stratified random block survey of at least one management unit in the North Thompson zone (preferably MU 3-40, the most heavily hunted) should be completed every 5 years To monitor trends in population structure, and thus assess productivity and the effects of harvest regulations, classification count surveys are recommended annually, in at least one MU within the North Thompson moose management zone. iii

4 North Thompson MooseClassification Surveys 2005 Table of Contents Summary ii Introduction 1 Background and Rationale 1 History of Moose Harvest Regulations in the North Thompson Zone 2 Wells Gray South Mountain Caribou Recovery 2 Study Area 3 North Thompson Moose Winter Ranges 3 Raft and Mad Rivers, Middle North Thompson River, Lower Clearwater River and Corridor (Management Unit 3-40) 3 Adams River (Management Unit 3-42) 3 Mud Creek (Management Unit 3-43) 3 Upper North Thompson River (Management Unit 3-44) 4 Green Mountain, Hemp Creek, Middle Clearwater River, Pyramid Mountain, Murtle River (Management Unit 3-46) 4 Methodology 4 Moose Classification Counts 4 Critical Moose Winter Range Mapping 5 Results 6 Moose Classification Counts 6 Raft and Mad Rivers (Management Unit 3-40) 7 Middle North Thompson River (Management Unit 3-40) 7 Lower Clearwater River and Corridor (Management Unit 3-39/3-40) 7 Adams River (Management Unit 3-42) 7 Mud Creek (Management Unit 3-43) 7 Upper North Thompson River (Management Unit 3-43/3-44) 7 Green Mountain and Hemp Creek (Management Unit 3-39/3-46) 7 Middle Clearwater River, McLeod Hill, Pyramid Mountain, Murtle River, Flourmill Burn (Management Units 3-39/3-40) 8 Moose Densities 8 Moose Winter Range Mapping 8 Evidence of Wolves 8 Discussion 13 Moose Classification Counts 13 Raft and Mad Rivers, Middle North Thompson River, Lower Clearwater River, Corridor (Management Unit 3-40) 13 Green Mountain, Hemp Creek, Middle Clearwater River, McLeod Hill, Pyramid Mountain, Murtle River, Flourmill Burn (Management Units 3-39/3-46) 13 Other North Thompson Moose Winter Ranges 14 iv

5 North Thompson MooseClassification Surveys 2005 Moose Densities 15 Moose Harvests 15 Bull Harvest 16 Cow/Calf Harvest 16 Impact of Wolves on North Thompson Moose Populations 18 Management Recommendations 18 References 20 List of Tables Table 1. North Thompson classified moose count personnel, January/February Table 2. North Thompson moose classified count survey effort and conditions, January/February Table 3. Estimated minimum wolf populations, North Thompson zone, July Table 4. Classified moose count data for North Thompson winter habitats, January/February Table 5. Moose population structure from classified moose count data, North Thompson area, January/February Table 6. Observed moose densities on North Thompson winter ranges, January/February Table 7. Population structure calculations based on classified count survey data, Management Unit 3-40, 1990, 1995 and Table 8. Population structure calculations based on classified count survey data, Management Unit 3-46, 1984 and List of Figures Figure 1. Region 3 estimated total moose harvest, Figure 2. Estimated bull moose harvest and hunter success rate, North Thompson area (MUs 3-40, 3-41, 3-42, 3-43, 3-44 and 3-46), List of Appendices Appendix 1 North Thompson moose classification counts study area 21 v

6 Introduction Background and Rationale Successful moose management depends on knowledge of local population distribution and structure and a reasonable estimate of population size; with this data in hand, wildlife managers can more confidently formulate sustainable moose harvest objectives and regulations. In its absence, managers are obliged to apply very conservative harvests to ensure herd sustainability. To address these data requirements in the most cost-effective manner, the Wildlife Section of the Ministry of Environment, Kamloops, conducts annual classified moose surveys in Region 3 management units (MUs), and has done so since the mid 1960s. The intent of these surveys is to classify as many animals as possible with respect to sex and age. These sample data are used to determine population structure, including sex/age ratios and composition. In turn, these serve as indicators for 1) the overall health and productivity of local populations and 2) the immediate and long-term effects of different moose harvest strategies implemented in the region. Since the late 1970s, very little moose population inventory work has been carried out in the North Thompson watershed. Classification surveys in Wells Gray Provincial Park (MU 3-46), completed in conjunction with a stratified random block survey, were undertaken by BC Parks in Management Unit 3-40 was surveyed in February 1990 and again in January of In the intervening decade, limited and inconsistent funding for surveys, and priority for available funds given to vulnerable moose herds in areas of high access and hunter pressure, has resulted in a complete lack of fundamental moose inventory data for the upper North Thompson units. The absence of current, reliable moose inventory data in the North Thompson prompted regional wildlife staff to seek and secure funding, through the Recreational Stewardship Inventory Fund, to complete classified moose counts in the upper North Thompson watershed during late January and early February The original, primary objective of the project was to establish a precise population estimate for a single management unit (i.e. MU 3-40) through the execution of a stratified random block survey. However, due to extended periods of unsettled weather and poor snow conditions throughout January and February 2004 and again in early January 2005, a decision was made to apply project funding towards less intensive coverage of a broader geographic area within the watershed. Further delay in the initiation of survey efforts would have significantly reduced moose sightability, as animals tend to move into heavier cover as the winter progresses. The broader geographic coverage of the classification surveys permitted refinements to existing moose winter range mapping to be completed concurrently. As such, the revised project objectives were: 1) Determine the age/sex composition of local moose populations on important winter ranges in the upper North Thompson watershed (MUs 3-40, 3-42, 3-43, 3-44 and 3-46). 2) Refine the extent of existing critical moose winter range mapping in the upper North Thompson watershed 1

7 3) Re-evaluate current moose harvest objectives and regulations in North Thompson wildlife management units. History of Moose Harvest Regulations in the North Thompson Zone In general, moose are managed to optimize population sustainability within ecosystems while allowing for options and opportunities for viewing and hunting (Ministry of Environment, Lands and Parks 1996). In 1984 and 1986 bull rut closures and antlerless limited entry seasons, respectively, in the southern portions of Region 3 were applied in response to classified count data indicating poor productivity. Decreasing pregnancy rates through the late 1980s prompted further restrictions on the bull harvest (i.e. closure of the pre-rut season in 1989). Meanwhile, seasons in the North Thompson remained relatively unchanged, other than a gradual shortening of the bull and antlerless seasons by approximately one week (Jury 1990). The remoteness, limited access and difficult hunting conditions in the area tend to keep hunting pressure considerably lower than in more southern management units, allowing for more liberal hunting seasons. An increase in the cow harvest, an absence of reproductive tract data (to provide pregnancy rates) and a lack of recent inventory data in the North Thompson prompted wildlife managers to shorten the bull season to three weeks post-rut and to close the antlerless season completely in 1989 with the intent of introducing limited entry antlerless hunts in Based on encouraging population composition data from classified counts completed in MUs 3-39 and 3-40 in the winter of 1990, cow/calf Limited Entry Hunts (LEH) were introduced for the 1990 season to provide antlerless opportunities which had been lost the previous year with the closing of the antlerless GOS. In 1993, regulations were simplified and standardized, with the institution of a region-wide 2-point (spike-fork) bull GOS and an any bull LEH. Since 1999, a GOS on spike-fork bull moose from September 20 through October 31 has been in place in the North Thompson MUs, with LEH for bulls only available through October and November and cow or calf LEH permits available for a 10-day period in early November. Wells Gray South Mountain Caribou Recovery The dynamic interaction between moose, wolves and caribou, where they exist together, is well known. Where moose numbers are high, they can provide the basis for an increased abundance of wolves (Bergerud and Ballard 1988). When opportunity permits, wolves will switch from preying on moose to preying on caribou, as these animals are the optimum size prey for wolves (even young wolves) and are easier to kill than moose. Moose are large, dangerous prey that are generally hunted by packs of greater than four wolves, which include experienced adults. Recovery of the threatened southern Cariboo Mountains mountain caribou population, including the Wells Gray South population, which inhabits the upper North Thompson watershed, may be advanced by a reduction of moose prey numbers through increased recreational moose harvests, which, ultimately, might reduce wolf abundance. Current, accurate moose inventory data may allow wildlife managers to confidently increase moose harvests within a trial area to test the alternate prey hypothesis: reduced prey (moose) will result in reduced predators (wolves) and consequently, increase survival of local caribou herds. However, the possibility of a lag effect should be noted: caribou may experience increased predation by wolves until the predator/prey relationships stabilize. 2

8 Funding for this project was provided by the BC Ministry of Environment through the Recreational Stewardship Inventory fund. The project would not have been possible without the enthusiasm and extraordinary skills of pilots K. Jackson and D. Smallman, Cariboo Chilcotin Helicopters Ltd. kudos for another job well done. Thanks to K. Van Damme and W. Chayer, BC Conservation Officer Service, for sharing their in-depth knowledge of local moose populations. To those who put on their moose eyes W. Chayer, K. Kier, I. McGregor, J. Surgenor and A. Wynnyk - many thanks. A special thank you to B. Rea for invaluable assistance with GIS. Thanks to D. Gibson and D. McNicol, BC Conservation Foundation, for administrative support. To D. Jury, BC Ministry of Environment, special thanks for continued guidance and encouragement. Study Area North Thompson Moose Winter Ranges Raft and Mad Rivers, Middle North Thompson River, Lower Clearwater River and Corridor (Management Unit 3-40) Historically, high quality moose winter habitats in Management Unit 3-40 have been identified in the Raft, Mad and North Thompson River drainages (Appendix 1). These sites are characterized by riparian shrub fens and meadows along the watercourses, and adjacent timber stands/regenerating cutblocks in the Interior Cedar-Hemlock biogeoclimatic zone. Elevations on these sites range from 450 m on the North Thompson River to 880 m in the upper Raft and Mad Rivers. Maximum elevations in the management unit occur on Raft Mountain (2450 m) where the Engelmann Spruce- Subalpine Fir zone predominates. The entire MU encompasses approximately 1500 km 2 ; critical moose winter habitats account for approximately 150 km 2 or 10% of the total area. Adams River (Management Unit 3-42) Important moose winter range in the Adams River corridor, located in Management Unit 3-42, extends from the north end of Adams Lake north (upstream) to the meadows north of Tumtum Lake. These sites lie within the Interior Cedar-Hemlock zone at elevations ranging between 450 m in the south and 850 m at Tumtum Lake. The Engelmann Spruce-Subalpine Fir zone occurs at higher elevations, with the Monashee Mountains in the eastern portion of the unit rising to 2450 m. The entire management unit covers approximately 1520 km 2 ; however, high quality habitats along the riparian corridor and extending into regenerating cutblocks above these sites, comprise about 70 km 2, or 5% of the total area. Mud Creek (Management Unit 3-43) The Mud Creek and Mud Lake moose winter range, located in Management Unit 3-43, represents only a very small portion (1%) of the approximately 1150 km 2 of the MU. These sites are typically riparian, shrub meadows bordering the watercourse itself, although adjacent timber in the Interior Cedar-Hemlock zone is also utilized for thermal and security cover. Most important winter foraging habitat occurs in the riparian zone at 3

9 approximately 700 m elevation. Maximum elevations in the unit (2770 m) occur in the icefields east of Mount Cheadle in the Monashee Mountains. Upper North Thompson River (Management Unit 3-44) Moose winter habitats within Management Unit 3-44 include riparian sites, low elevation timber stands, and regenerating cutblocks along the lower reaches of Blue River, Lempriere Creek, Manteau Creek and the North Thompson River bottomlands. Comprising approximately 2% (40 km 2 ) of the 1740 km 2 total area of the management unit, these sites range in elevation from 700 m to 1070 m, and are situated in the Interior Cedar-Hemlock biogeoclimatic zone. The icefields of the Cariboo Mountains in the western portion of the MU are found at elevations around 2400 m. Green Mountain, Hemp Creek, Middle Clearwater River, Pyramid Mountain, Murtle River (Management Unit 3-46) The largest of the North Thompson management units, MU 3-46 encompasses approximately 3240 km 2 and includes a large portion of Wells Gray Provincial Park. Important moose winter range has been identified on the Clearwater River (from Hemp Creek north to Lone Spoon Creek), Hemp Creek and its tributaries and Green Mountain. Elevations in the unit range from approximately 550 m on the Clearwater River and Hemp Creek at Green Mountain to 2880 m at Garnet Peak, north of Azure Lake. Moose winter ranges are generally situated between 550 m and 980 m in the Interior Cedar- Hemlock zone, with historically high density habitats located in the Green Mountain and Hemp Creek area. These habitats and others identified as high quality moose winter range comprise approximately 3% of the total area of the management unit. At higher elevations (from approximately 1500 m), the Engelmann Spruce-Subalpine Fir and Alpine Tundra zones predominate. Methodology Moose Classification Counts Classification count surveys were conducted using a Bell 206B helicopter. Two experienced pilots were used, with the same navigator and primary observer present for all flights (Table 1). Secondary observers varied throughout the surveys. The navigator entered animal locations (waypoints) into a Garmin GPSmap 76C (Garmin Industries, Olathe, Kansas, USA) and plotted winter range boundaries and animal locations on 1: topographic and/or orthographic photo maps. Flight tracking was recorded automatically in the GPS unit. The primary observer recorded animal classification, geographic location and habitat data on standardized hard-copy data forms. All in-flight personnel contributed to locating and classifying animals. 4

10 Table 1. North Thompson classified moose count personnel, January/February 2005 Management Unit Area Survey Date Navigator Observer 1 Observer 2 Pilot 3-40 Raft R. & Mad R. 29 January S. Lemke D. Jury W. Chayer K. Jackson 3-42 Adams R. 1 February S. Lemke D. Jury K. Kier D. Smallman 3-40 Middle N. Thompson R. 7 February S. Lemke D. Jury K. Kier D. Smallman 3-43/3-44 Upper N. Thompson R. 6 February S. Lemke D. Jury J. Surgenor K. Jackson 3-39/3-40 Clearwater R. (lower), Corridor 11 February S. Lemke D. Jury A. Wynnyk K. Jackson 3-39/3-46 Green Mtn., Hemp Cr. 11 February S. Lemke D. Jury A. Wynnyk K. Jackson 3-39/3-46 Clearwater R. (middle), Pyramid Mtn., Murtle R., Flourmill Burn 14 February S. Lemke D. Jury I. McGregor K. Jackson In efforts to maximize moose sightability rates and, thus, achieve adequate sample sizes, areas of known or expected high moose densities, such as riparian meadows, water courses, aspen/willow stands, brushy regenerating cutblocks and burns were targeted during survey flights. Although the moose sighted in these high quality forage areas may not be representative of the local population (bulls are thought to use higher elevations than cow/calf pairs at this time of year), consistent annual surveys of the same habitats should provide reliable population trend data (Jury 1990). The aircraft was flown between approximately 60 m and 120 m above ground, depending on terrain and vegetative cover. In general, denser vegetative cover was flown at higher altitude, while more open habitat was covered at lower altitudes. Air speed was maintained between 80 kph and 100 kph. Critical Moose Winter Range Mapping During the course of moose classification surveys, areas determined to be of high winter value to moose were recorded. Site assessments were based on habitat attributes, such as elevation, slope, aspect and vegetation, the presence/absence and, where present, the density of animal sign, i.e. tracks or beds, and on actual animal sightings. Assessments were discussed and established by survey personnel in-flight and polygon boundaries drawn freehand onto 1: scale topographic and 1: scale orthographic photobased maps. The topographic coverage allowed more accurate delineation of polygon boundaries based on elevation, while boundaries based on features of the habitat, i.e. regenerating cutblock edge, were more easily established using orthographic photo-based mapping. These boundaries are currently being digitized in a Geographic Information 5

11 M.U. System (GIS) coverage, and incorporated into a layer with existing winter range coverage for comparison purposes. Results Moose Classification Counts A total of 18.5 hours was spent in searching for and classifying moose within known or expected high density moose winter habitats in the North Thompson management units (Table 2). Additional charter (15.8 hours) was attributed to ferry time, i.e. from Kamloops base of operations to survey areas and return, and from survey areas to local fuel caches and return. Survey conditions were generally favourable, with high overcast/clouds or clear skies and calm winds. Temperatures ranged from a high of +2ºC to a low of -14ºC. Snow conditions were poor for conducting moose surveys; the snowpack level was low and the snow that was present was old, making it difficult to detect recent moose activity from tracks. Snow depth at Blue River (elevation 670 m) at the time of the classified moose surveys was 65% of the 23-year normal level and measures of snow density were 40% above normal. As an index of survey effort, moose sighting rates were calculated based on the total search time and the total number of moose sighted. These values ranged from 12 moose/hour in the Raft and Mad River drainages (MU 3-40) to 39 moose/hour at Green Mountain/Hemp Creek (MU 3-46), bracketing the regional average sightability rate for classification counts of 25 moose/hour. A summary of animal classification data for each identified North Thompson moose winter range surveyed is presented below in Table 4. Population composition and sex ratios calculated from these data are presented in Table 5. Table 2. North Thompson moose classified count survey effort and conditions, January/February 2005 Date Hours searched Total charter Sky conditions January Overcast; calm February Sunny periods; light wind; Snow conditions Last snow 13 days ago; ~ 30 cm 8 cm fresh snow over hard crust Temp ( C) Moose sighting rate (Moose/hour) +2ºC 12-14ºC 20 7 February Overcast Not recorded 0ºC February Clear; calm Not recorded -10ºC February Overcast; calm < 30 cm -6ºC February Totals Overcast, sunny periods; calm Old; < 60 cm -8ºC 17 6

12 Raft and Mad Rivers (Management Unit 3-40) The 29 January survey of the Raft and Mad River drainages recorded 25 moose sighted, 24 of which were successfully classified: 1 adult bull, 8 cows, 3 calves (a single and 1 set of twins) and one unclassified adult. On the Mad River range, 12 animals were classified: 5 bulls (1 yearling and 4 adults), 5 cows and 2 calves. Based on this extremely limited sample, the bulls per 100 cow ratios are 13 and 100 for the Raft and Mad Rivers, respectively. The cow/calf ratios for these sites are 38 and 40 calves per 100 cows, respectively. Middle North Thompson River (Management Unit 3-40) The productive North Thompson River riparian corridor in this area yielded 29 moose sighted and classified, including 10 bulls, 14 cows and 5 calves. Seventy-nine percent of the cows observed were not accompanied by calves. Of the remaining 21% (3 cows), one had a single calf and two were sighted with twins. The classification of this sample indicates population composition of 71 bulls per 100 cows and 36 calves per 100 cows. Lower Clearwater River and Corridor (Management Unit 3-39/3-40) The survey of the lower Clearwater River and the Corridor (east side of Clearwater River from Spahats Creek north to Moul Creek) recorded 26 moose. Thirteen bulls, 8 cows (5 lone, 2 tending single calves and 1 with twin calves) and 5 calves comprised the total. The bull per 100 cow and calf per 100 cow ratios were 163 and 63, respectively. Adams River (Management Unit 3-42) Significant moose winter range in the Adams River valley was surveyed on 1 February. Fifty-two moose were classified: 15 bulls, 28 cows (19 lone and 9 attending single calves) and 9 calves. The resulting population composition ratios were: 32 bulls per 100 cows and 54 calves per 100 cows. Juveniles represented 17% of classified individuals. Mud Creek (Management Unit 3-43) The limited extent of moose winter habitat in the Mud Creek drainage (~ 12 km 2 ) held 25 visible moose on 7 February: 2 bulls, 17 lone cows and 3 cows with calves. This small sample yielded the following composition ratios: 10 bulls per 100 cows, 15 calves per 100 cows and a juvenile component of 12%. Upper North Thompson River (Management Unit 3-43/3-44) Survey efforts classified 32 moose in MU Nine bulls were classified, as well as 15 cows and 8 calves. Fifty-three percent of cows were accompanied by calves. Population composition indices calculated from this sample include a bull/cow ratio of 60 bulls per 100 cows, 53 calves per 100 cows and a juvenile component of 25%. Green Mountain and Hemp Creek (Management Unit 3-39/3-46) One hundred and sixty-nine moose were successfully classified, while 10 adults remained unclassified as to sex. Fifty-nine bulls, 85 cows (63 without young, 20 accompanied by a single calf and 2 with twin calves) and 25 calves (including one lone calf) comprised the 7

13 total. Calves represented 14% of the sample, while the bull/cow and calf/cow ratios were 69 and 29 per 100 cows, respectively. Middle Clearwater River, McLeod Hill, Pyramid Mountain, Murtle River, Flourmill Burn (Management Units 3-39/3-40) Moose winter range widely scattered throughout this area was targeted during survey flights, during which 48 animals were sighted. Six of these were recorded as unclassified adults, while 9 bulls, 24 cows and 9 calves completed the count. Seventeen of the cows appeared not to have young, five had single calves and two were supporting twins. Nineteen percent of the animals sighted were juveniles, with ratios of 38 bulls per 100 cows and 38 calves per 100 cows derived from the sample. Moose Densities Observed moose densities on important winter ranges in the North Thompson zone ranged from 0.16 to 4.26 moose/km 2 (Table 6). The lowest observed densities were recorded in the Raft and Mad River valleys, 0.16 and 0.25 moose/km 2, respectively, with considerably higher densities observed along the lower Clearwater River (0.59) and the North Thompson River (0.65), also in MU Observed moose densities in early February 2005 were 0.74 moose/km 2 in the Adams River valley (MU 3-42), 2.08 moose/km 2 along Mud Creek (3-43), 0.35 moose/km 2 in the upper North Thompson River drainages, 4.26 moose/km 2 on Green Mountain and 0.81 moose/km 2 on the upper Clearwater River, Pyramid Mountain/Murtle River area. Moose Winter Range Mapping The extensive geographic coverage of the 2005 North Thompson classified moose surveys provided an invaluable opportunity to ground-truth and refine existing moose winter range polygons. Updating of moose winter range capability mapping and identification of the (current) highest value moose wintering areas have been identified as key areas requiring attention within the Kamloops Land and Resource Management Plan (LRMP), which was developed a decade ago. To this end, Land Information BC Geographic Information Systems (GIS) operators, under the direction of regional wildlife and habitat staff, are currently integrating existing moose inventory data (including those from these surveys), winter range polygons predicted from the TUWR ( Topographic Ungulate Winter Range model) and those developed under the LRMP process. Over the next few months, moose winter range polygon boundaries recorded during the 2005 North Thompson moose survey flights will be digitized into the existing GIS coverage, where its layer will be compared with the inventory, model and LRMP results. With refinements complete, and further identification and accurate delineation of core winter habitats, this process should provide wildlife managers with a comprehensive, useful tool with which to develop management objectives and strategies for moose winter range both within the LRMP area, and, by extension, throughout the region. Evidence of Wolves No wolves were sighted during moose classification counts. Wolf tracks were observed at an adult moose carcass in the Raft River (MU 3-40) on 29 January. The local trapper 8

14 subsequently confirmed that this was a wolf kill. A calf moose kill was investigated in Hemp Creek (MU 3-46) on 11 February. The kill was not recent and the number of wolves attendant was difficult to determine, as the snow was old and hard crusted. Another old calf kill, uncovered by coyotes, was investigated in Mud Creek on 6 February. Ongoing work to trap, tag and monitor wolves in the upper North Thompson River region (in conjunction with mountain caribou recovery work) has provided a basis for determining minimum wolf pack sizes and distribution (Table 3) (K. Kier, pers. comm.). Currently, two individuals (1 sub-adult female and 1 adult male) fitted with radio collars and two individuals fitted with GPS collars (1 adult female and 1 adult male) are being monitored in the upper North Thompson River, Serpentine Creek, Moonbeam Creek and Barry Creek areas. Table 3. Estimated minimum wolf populations, North Thompson zone, August Management Unit Area Minimum Population 3-40 Raft River 4-8 Comments Mad River? Movement between Mad and Barry Creek Barry Creek 8-10 Movement between N. Blue R. and Murtle Lake? 3-42 Adams River 4-6 Move between upper Seymour River 3-43 Mud Creek 5-7 Movement south into Tumtum 3-43 Serpentine/Moonbeam Creeks 3-44 Upper North Thompson River 12 Upper N. Thompson, Albreda R. south to Mud Creek 3-46 Wells Gray Park (south) 10 9

15 Table 4. Classified moose count data for North Thompson winter habitats, January/February 2005 Moose Winter Range Bulls Total Bulls Cows Total Cows Lone Calf Total Calves U/C Adult U/C Moose Total Moose Adult* U/C Lone cow Cow with 1 Cow with 2 Raft River (MU 3-40) Mad River (MU 3-40) Lower Clearwater R., Corridor (MU 3-39/3-40) Middle N. Thompson River (MU 3-40) Adams River (MU 3-42) Mud Creek (MU 3-43) Upper N. Thompson River (MU 3-43/3-44 Green Mountain, Hemp Creek (MU 3-39/3-46) Middle Clearwater R., McLeod Hill, Pyramid Mtn., Murtle River, Flourmill Burn (MU 3-39/3-46) Totals *Adult bull category includes sub-adult males 10

16 Table 5. Moose population structure from classified moose count data, North Thompson area, January/February 2005 Moose Winter Range Total Moose Ratios Composition (%) Bulls Cows Calves Bulls Cows Calves Raft River (MU 3-40) Mad River (MU 3-40) Lower Clearwater R., Corridor (MU 3-39/3-40) Middle N. Thompson River (MU 3-40) Adams River (MU 3-42) Mud Creek (MU 3-43) Upper N. Thompson River (MU 3-43/ Green Mountain, Hemp Creek (MU 3-39/3-46) Middle Clearwater R., McLeod Hill, Pyramid Mtn., Murtle River, Flourmill Burn (MU 3-39/3-46) Totals

17 Table 6. Observed moose densities on North Thompson winter ranges, January/February 2005 Moose Winter Range Area of Surveyed High Density Winter Range (km 2 ) % of MU Area Surveyed Moose Observed Observed Density (Moose/km 2 ) Raft River (MU 3-40) MU Population Estimate Mad River (MU Lower Clearwater R., Corridor (MU 3-39/3-40) Middle N. Thompson (MU 3-40) Total Adams River (MU 3-42) Total Mud Creek (MU 3-43) Total Upper N. Thompson (MU 3-43/3-44) Total Green Mountain, Hemp Creek (MU 3-39/3-46) Middle Clearwater River, McLeod Hill, Pyramid Mountain, Murtle River, Flourmill Burn (MU 3-39/3-46) Total Grand Total

18 Discussion Moose Classification Counts Raft and Mad Rivers, Middle North Thompson River, Lower Clearwater River, Corridor (Management Unit 3-40) Scant historical data describing moose population composition exist for MU The most recent classified count was conducted in 1995, with another effort 5 years previous in 1990 (Table 7). These indices have remained relatively stable, particularly when those based on similar sample sizes are compared, i.e and The current ratios suggest a healthy, stable or increasing population. The calf ratio is particularly encouraging, exceeding the long-term regional average of 40. This suggests that factors affecting calf survival, such as predation, poor habitat suitability, disease and difficult winter conditions, are not significantly affecting this population at present. Observations of healthy twin calves on the Raft River, Duncan Creek (lower Clearwater River) and near Messiter on the middle North Thompson River suggest the nutritional status of cows in these areas is good, indicating high quality winter habitat. Similarly, the bull component appears strong; the majority of bulls classified in the 2005 survey were adults, and therefore, potentially in the breeding population. This high bull ratio is indicative of a lightly harvested population. However, small sample size and the lack of a consistent time series of data from which a population trend can be determined preclude any definitive conclusions. Table 7. Population structure calculations based on classified count survey data, Management Unit 3-40, 1990, 1995 and Date Total Moose Observed Ratios Composition (%) Bulls Cows Calves Bulls Cows Calves Green Mountain, Hemp Creek, Middle Clearwater River, McLeod Hill, Pyramid Mountain, Murtle River, Flourmill Burn (Management Units 3-39/3-46) The first reported aerial moose census was undertaken in Wells Gray Park in At this time, no published accounts of aerial counts of moose were extant, although the technique had been tried in Ontario and in the Northwest Territories (Edwards 1952). The area surveyed included the high quality winter ranges at Green Mountain, Hemp Creek and Trout Creek. On three separate fixed-wing flights in early March, observers sighted 129, 137 and 111 moose, respectively. No attempt was made to classify animals as to age and sex. At this time, the author estimated the moose population within and adjacent to Wells Gray Park to be In 1984, the Parks Branch completed a stratified random block survey, followed by two classified counts (Sather & Jones 1984). 13

19 The calculated wintering moose population estimate from this survey was 850 animals. Composition data from the classified counts, which covered a similar geographic area as the 1952 efforts (and the 2005 survey) were variable between the two survey dates (Table 8). The authors suggest that these differences resulted from changes in sightability and animal movements. The current calf:cow ratio of 31:100 matches an average determined from the 1984 counts. Considerably lower than the long-term regional average of 40, the reduced recruitment may be a result of bear and wolf predation. However, regular monitoring of the population will be required to determine how these data fit into the long-term trend in calf survivorship and recruitment. The bull ratio is considerably lower than those reported by Sather and Jones in During the 2005 survey, snow cover was quite patchy, suggesting that snow depths at higher elevations were low. These conditions may have encouraged bulls to remain (or return) to higher elevations, while cow/calf groups occupied prime winter habitats. Bulls region-wide are suspected to use higher elevations, in general, at this time of year, regardless of snow conditions. Regardless, this ratio is suggestive of a healthy bull component more than adequate to service estrus cows. Population composition has remained remarkably stable, with an average of 35% bulls, 47% cows and 15% calves; however, this reveals little about trends in the intervening years. Table 8. Population structure calculations based on classified count survey data, Management Unit 3-46, 1984 and Date Total Moose Observed Ratios Composition (%) Bulls Cows Calves Bulls Cows Calves * January February *Average number of moose seen on the same 100 km 2 winter range on three consecutive survey days. Other North Thompson Moose Winter Ranges With formal inventory data completely lacking for the remaining high value winter ranges in the North Thompson, an assessment of trends in moose population composition and productivity trends is impossible. However, based on the 2005 classification surveys, the status of these populations can be described. Juvenile recruitment and bull ratios in the Adams River drainage and the upper North Thompson area are robust, indicating that 1) factors negatively impacting calf survival, including predation, are not currently affecting the moose population in these areas and 2) bull harvests, at current levels, are sustainable and that there may be additional opportunities (see below). The observed bull and calf ratios in the Mud Creek drainage were alarmingly low. Although the small sample size (25 animals) may, in part, account for this result. 14

20 However, significantly, much of the recent wolf activity in the upper North Thompson River area has been reported in this valley and in drainages immediately to the north. A pack of 5-7 adults and their tracks were reported regularly through the winter months of 2005, and 2 adults and seven pups were observed in Serpentine Creek (approximately 30 km to the north of Mud Lake) in July. It is unclear whether these animals form two separate packs or are members of a single group, although the latter scenario has been suggested more likely (K. Kier, pers. comm.). As evidenced by the calf mortality investigated in Mud Creek, wolf predation is likely the cause of low calf survival. Bulls may be displaced to less favourable habitats by wolves, which would leave them outside the scope of the classification survey methodology, i.e. searching of highest quality winter habitats only. Moose Densities The forced change in survey methodology from the more intensive stratified random block count to classification counts precluded the calculation of an accurate, statistically defensible population estimate. However, observations within high quality areas indicate healthy moose numbers. A small portion of each management unit in the zone was surveyed for these classification counts (approximately 10%, 5%, 1%, 2% and 3% in MUs 3-40, 3-42, 3-43, 3-44 and 3-46, respectively). Much of the land base is not capable moose habitat; for example, the northern portion of MU 3-46 in Wells Gray Park, where icefields dominate. Although the survey coverage was distinctly biased toward high quality range of known high winter densities, it became evident that, unlike elsewhere in the Nicola and Bonaparte areas, high value moose winter ranges in the North Thompson region are very obviously delineated; there appears to be little in the way of transition between high and low quality range. In more southern MUs, the topography, i.e. ranges of low hills and valleys and plateaus, lends itself to extensive areas of moderate density winter range between lower elevation, high quality riparian and wetland sites and higher elevation, snow limiting, timbered habitats of little winter value to moose. In the North Thompson, abrupt elevational changes limit this transitional habitat, which can, and does, support fair numbers of moose in the southern parts of the region. As a result, winter densities are significantly higher in the North Thompson than in the Nicola and Bonaparte areas, as animals are concentrated on less available low elevation winter range. These classification counts certainly did not cover every high value moose wintering site; we suspect there are many pockets of suitable winter range which may, in total, support significant numbers of moose. There may also be animals wintering on different habitat types than those classic moose winter ranges targeted by classification count surveys. Moose Harvests The increasing productivity of Region 3 moose populations, including those in the North Thompson management units (MUs 3-40, 3-41, 3-42, 3-43, 3-44 and 3-46), is reflected in hunter harvest data. Regionally, there has been a steady increase in the total harvest over the past decade (Figure 1). Although variable, there has also been a slight increase in the hunter success rate during this period (Figure 2). Taken together, these results are indicative of a moose population increasing in numbers, and the healthy population composition data reported for the 2005 surveys suggest that current harvest rates are sustainable and may be increased to stabilize population growth (see below). 15

21 Bull Harvest Before 1998, the annual allowable bull harvest (AAH), which is set at 20% of the estimated adult bull population, did not include 2+ year-old bulls. This resulted in a very conservative harvest. Beginning in 1998, the AAH was adjusted to include 2+ year-old bulls. Due in part to this change, resident LEH permits in the North Thompson units have doubled since 1995 (from 76 in 1995 to 160 in 2005). The increase in opportunities could be responsible for increased harvests; however, there has been a proportional increase in the kill rate with the increased harvest. For example, in 1998, the 3-year average bull harvest in the North Thompson MUs was 28, with an AAH of 54 (52% harvest rate). For the 2005 season, the AAH allocated is 68; the 3-year average harvest before the current year was 48, or 71% of the AAH (Figure 2). The objective of existing harvest management regulations is to continue to build the number of permits, taking into account hunter success, until the AAH is reached. Interestingly, the 2004 bull harvest in the North Thompson MUs was 65, with an AAH of 68. In this case, the AAH was met or exceeded in some management units, i.e. hunter success rate was high. Typically, harvests in MU 3-46 fall well below the AAH, due to vehicle access restrictions and a widely distributed moose population during the hunting season in Wells Gray Provincial Park. Cow/Calf Harvest A reduction of moose numbers through increased recreational harvest, which may reduce wolf abundance, has been suggested as an approach to reducing wolf predation impacts on threatened mountain caribou populations which will, theoretically, increase caribou survival and recruitment. Moose population control cannot be achieved through bull harvests; harvest must be targeted toward cows and calves. Historically, cows (and calves) have been intentionally under harvested across Region 3, in an effort to ensure sustainable moose populations. Currently, the average cow harvest in the North Thompson area is 30-35% of the antlerless AAH. However, an immediate and dramatic increase in cow harvest, and the resulting reduction in productivity, may cause a rapid shift of wolf predation from moose to caribou. With fewer moose calves available as prey, wolves, given the opportunity, would likely select the smaller, less dangerous, caribou instead of an adult moose. A gradual decline in moose numbers, affected by a reduction in recruitment through calf harvests, should result in a slower shift of predation pressure onto caribou while wolf numbers are decreasing. Should the alternate prey management approach be adopted, an open calf moose season could be an effective option. Wells Gray Provincial Park sustains much of the North Thompson s moose population (approximately 40%) and contains much of the region s caribou habitat. To manage alternate prey within the park, a logical first step might be a cow LEH season. In the past, a January cow moose hunt was carried out to manage moose numbers and provide hunting opportunities. However, locals and winter recreationists were opposed to the aesthetics of the hunt, i.e. evidence of game butchering. A cow season in November would avoid these issues; however, hunters would be pursuing local moose. These resident animals are an important component of the wildlife viewing opportunities in the park. To target migratory animals, a December LEH season might be a better option. 16

22 Estimated total harvest Figure 1. Region 3 estimated total moose harvest, Bull harvest 25 Estimated total bull harvest % Hunter success % Hunter success Figure 2. Estimated bull moose harvest and hunter success rate, North Thompson area (MUs 3-40, 3-41, 3-42, 3-43, 3-44 and 3-46),

23 Impact of Wolves on North Thompson Moose Populations Little evidence of wolf activity in the areas surveyed and the strong overall calf moose ratios suggest that wolves are not, at present, negatively affecting moose numbers and productivity in the North Thompson area (see below for exception). Considering the extent of the area surveyed, more evidence of wolf activity would be expected if these predators were a significant factor in limiting local moose populations. The nature of moose classification counts, i.e. concentration on open, riparian and deciduous-type habitats, and the lack of fresh snow (making track sightings difficult from the air), make it likely that evidence of wolf activity and wolves themselves were missed; however, the low occurrence of observed wolf kills and the strong juvenile moose recruitment observed would certainly not be expected in a predator-limited moose population. The wide dispersal of moose throughout the zone during the summer months may be limiting wolf numbers, as considerable effort would be required of small packs to locate and kill these animals (D. Jury, pers. comm.). Whether wolf numbers are sufficient to significantly impact local mountain caribou herds is currently unknown and under investigation (see below). Grizzly bears and black bears are considered the most important source of calf moose mortality in many studies across North America (Ballard 1992). Therefore, it is reasonable to suspect that caribou calves may be just as susceptible, if not more so, to bear predation than young moose (cow moose, which are much larger than female caribou, will aggressively defend their calves). As mentioned previously, the cow/calf ratio in the Mud Creek drainage is low (15 calves per 100 cows). Small sample size, in part, may account for this result, although significant wolf activity in the upper North Thompson River area has been reported in this valley and in drainages immediately to the north. A pack of 5-7 adults and their tracks were reported regularly through the winter months of 2005, and survey personnel recorded the tracks of at least four individuals around the shoreline and crossing Mud Lake on 7 February. Continuing observations of radio collared wolves in this area, and monitoring of recently collared moose in the Raft, lower Clearwater and Murtle River areas may shed light on the nature of wolf predation on this species. The significance of wolf predation on mountain caribou productivity may also be investigated through monitoring of these tagged animals and continued observations of existing radio collared caribou. Management Recommendations Moose numbers in southern British Columbia have been increasing over the past decade (D. Jury, pers. comm.; Poole et al. 2003). In the North Thompson MUs, as in other areas, the increase has likely been stimulated by habitat changes brought about by timber harvesting and amplified by mortality and harvest rates inadequate to stem population growth. With current moose harvests falling short of the AAH, the objective of harvest management regulations is to continue building the number of permits, taking into account hunter success, until the AAH is reached. Based on observations and from the 2005 surveys, an increase in the bull AAH could be considered. More significantly, if stabilization (or reduction) of the growing moose population is the objective, added cow 18