Thompson Moose Composition Surveys

Transcription

1 Thompson Moose Composition Surveys Management Units: 3-28, 3-31, 3-36, 3-42 Winter 2013 Prepared by: Francis Iredale, R.P.Bio & Chris Procter, R.P.Bio Fish & Wildlife Ministry of Forests, Lands & Natural Resource Operations Kamloops, BC March 2013

2 Table of Contents Introduction... 3 Survey Area... 3 Methods... 6 Results... 7 Wildlife Management Unit Wildlife Management Unit Wildlife Management Unit Wildlife Management Unit Discussion Wildlife Management Unit Wildlife Management Unit Wildlife Management Unit Wildlife Management Unit Conclusion Recommendations Acknowledgements Literature Cited Table of Figures: Figure 1. Thompson Region Management Units where moose composition surveys were completed, winter Figure 2. Moose observations and flight path within WMU 3-28 LEH zones A & B (January and February 2013). Inset photo of respective burn habitat in LEH Zone A Figure 3. Moose observations and flight path within WMU 3-31 (February 2013). Inset photo: Wetland meadow habitat within WMU Figure 4. Moose observations and flight path within WMU 3-42 (January 2013) Figure 5. Moose observations and flight path within WMU 3-36 (February 2013). Inset photos: Scotch Creek Moose winter habitat and wolf pack of 5-6 animals observed near the Ratchford River confluence

3 List of Tables: Table 1. Naive and corrected moose population composition for WMU 3-28 and for 3-28 LEH Zones A & B respectively Table 2. MU 3-28 Uncorrected sex and age ratios from post hunt surveys, Table 3. Naive and corrected moose population composition for WMU 3-31, Table 4. Uncorrected sex-age ratios from post hunt surveys WMU 3-31, (NR- not recorded).. 9 Table 5. Naive and corrected moose population composition for WMU 3-42, Table 6. Uncorrected sex-age ratios from post hunt surveys WMU 3-42, (NR- not recorded) Table 7. Naive and corrected moose population composition for WMU

4 Introduction Moose (Alces alces) are an important game species for resident and non-resident hunters in the Thompson Region and are culturally important as sustenance for First Nations. Provincially, the Thompson Region supports the second highest hunter effort in terms of resident hunter numbers and days for moose. Data derived from composition surveys enables regional wildlife biologists to monitor moose population demographics, trends (e.g. sighting rates), distribution, and assess populations relative to harvest regulations and ministry performance measures, such as the maintenance of a posthunt bull:cow ratio that exceeds 30 Bulls: 100 cows. In lieu of information derived from costly stratified random block surveys, the annual acquisition of these data is an essential component of moose management in the Thompson Region. Moose composition surveys in 2012/13 focused on Wildlife Management Units (WMUs) where regional biologists suspected moose populations had declined (e.g & 3-42) and where bull ratios were believed to be near ministry performance measure (e.g. 3-28). These surveys also provided insight into the effects of the 2010 spike/fork bull General Open Season (GOS) season reduction on bull ratios in WMU There is very high resident interest in moose hunting opportunities, particularity GOS opportunities in these zones. Currently, WMUs 3-28, 3-31, 3-36 and 3-42 support 22% of the total number of moose hunters in the Thompson Region. The primary objective with this report is to summarize data from the 2012/13 post-hunt composition surveys conducted in WMUs 3-28, 3-31, 3-36, and 3-42 and compare results with previous surveys. Funding for the completion of these compositional surveys was provided by Land Base Investment Fund. Survey Area Moose composition surveys were conducted in WMUs 3-28, 31, 36 and 42 (Figure 1). The area is varied in topography, habitat type and climatic conditions. Survey areas encompass seven biogeoclimatic zones: the Interior Cedar Hemlock (ICH), Montane Spruce (MS), Interior Douglas-fir (IDF), Englemann Spruce- Subalpine Fir (ESSF), Sub-boreal Spruce (SBS), Ponderosa Pine (PP), and Bunchgrass (BG). Forestry is the main industrial activity on the land base and harvesting has accelerated in recent years to salvage dead and dying timber from the mountain pine beetle epidemic. This has led to an increase in road densities and loss of forest cover for moose. Loss of cover around sensitive wetlands may lead to alienation of important habitat. Cattle grazing is another prominent activity and heavy summer and fall browsing by cattle within wetlands and adjacent riparian habitat removes important shrub vegetation, e.g. willow, an important forage for moose. WMU 3-28 falls within the Thompson-Okanagan Pleateau Ecoregion. A prevailing transitional climate enables exchange between the southern drier and warmer climates and the moister and cooler climates to the north (Demarchi 1996). Engelmann spruce, subalpine fir, and lodgepole pine (Pinus contorta) occupy sub-alpine areas (Demarchi 1996). Lower elevations support lodgepole pine forests with pine grass understory, mixed with some trembling aspen (Populus tremoloides), and interior Douglas-fir (Pseudotsuga menziesii var. Glauca). Douglas-fir and understory pine grass (Calamagrostis rubescens) or parklands of scattered ponderosa pine (Pinus ponderosda) interspaced with bluebunch wheat grass (Pseudoroegneria spicata) and sagebrush (Artemisia tridentate) occupy valley bottoms (Demarchi 1996). This unit features several historic fire events, the most notable being the 2003 McLure Fire. 3

5 The mountainous terrain of WMU 3-31 occurs within a transitional zone between the Coast Range to the west and the Interior Plateau to the east. This unit contains the Marble and Clear Ranges, Edge Hills and the northern extension of the Cascade Mountains (Demarchi 1996) and portions of the southern Cariboo Plateau. Sagebrush-steppe and ponderosa pine forests dominate the Fraser valley while Interior Douglas-fir and Montane Spruce forests occur on the upper slopes and plateau. Several pothole lakes and marshes reside within this WMU providing excellent foraging habitat for moose. This zone also features the scars of several fires, most recently the 2009 Edge Hill fire. WMUs 3-36 and 3-42 occur within the wet belt of the Shuswap drainage, which encompasses the upper Adams River, Adams Lake, Seymour and Shuswap River (Figure 1). The Columbia Highland and North Columbia Mountain Ecoregions overlap these management units. Snow fall accumulations can be heavy as a result of moist Pacific air rising over these highlands. Interior Cedar (Thuja plicata) and Hemlock (Tsuga heterophylla) occur within the valley bottom and lower slopes; while Engelmann Spruce (Picea engelmannii) and Subalpine Fir (Pinus lasiocarpa) forests occupy the middle and upper mountain slopes (Demarchi 1996). Wolves (Canis lupus), black bears (Ursus americanus), and cougar (Felis concolor) are the primary predators within WMUs 3-28 and 3-31, with the addition of Grizzly bear (Ursus arctos) for WMUs 3-36 and Other ungulate species that occur within the survey areas include: mule deer (O.heminonus), white-tailed deer (Odocoileus virginainus), mountain goats (Oreamnos americanus), bighorn sheep (Ovis Canadensis), and sporadic occurrences of Rocky Mountain Elk (Cervus canadaensis). 4

6 Figure 1. Thompson Region Management Units where moose composition surveys were completed, winter

7 Methods Moose winter ranges, typically consisting of early seral open habitats such as young clearcuts, open mixed coniferous and deciduous stands, burns, riparian complexes and meadows, were systematically searched using a bubble window equipped Bell 206B helicopter using an experienced primary observer/navigator in the front and qualified secondary observers in the rear. We used the program GIS Roam uploaded onto an Apple Ipad for navigational purposes. Transects were spaced approximately meters apart and meters above ground at air speeds of up to 100km/hr. Densely vegetated areas were surveyed at slower speeds (80 km/hr) and at higher elevation above ground and conversely, large areas of open habitat were covered quicker. Contour transects were used on sloped terrain. We increased elevation until it was obvious, based on observations of moose and their sign, that we were above the wintering elevation of moose in the study area. All in-flight personnel assisted with locating and classifying moose. All moose were classified as bulls, cows or calves. Bulls were further classified as yearlings, teens or adults depending on their general appearance and antler architecture, if present. Rostrum colouration, bell size and shape and the presence of a white vulval patch were used to identify cows. Calves were identified based on body size and appearance (square blocky body) and short rostrum length. We estimated vegetation cover as percent oblique cover around each moose to the nearest 10%, starting at 5%, within a radius of 10 meters from the animal s location (Unsworth et al. 1999). For groups of moose, cover was estimated around the animal first observed and applied to the group later. We regularly discussed and standardized our estimates of vegetative cover. When possible, photographs of moose were recorded using a Canon XT rebel camera. Incidental observations of wolves or their tracks were also recorded. To account for differential habitat use by age and sex classes of moose, a sightablity model was applied to composition data to correct population ratio estimates. We used detection probabilities estimated by Quayle et al. (2001) and later updated using trial data from the Prince George area, commonly referenced as the BC Model, in Program AERIAL SURVEY to correct population ratios. Program AERIAL SURVEY uses a single adult bull category for all bulls older than a yearling; therefore all bulls older than yearlings were pooled into the same adult bull category. Bootstrapping was used in Microsoft Excel to derive 90% confidence intervals for naive and corrected population ratios. Respective survey maps were produced using ArcMap 9.3. Survey results were submitted to the provincial Species Inventory Database (SPI). 6

8 Results Wildlife Management Unit 3-28 Survey conditions Classification counts for WMU 3-28 Limited Entry Hunt (LEH) Zones A & B were conducted on January 4 th and February 12 th, Snow cover was complete throughout the entire survey area with snow pillar data measured at Knouff Lake (approx 6km east of the WMU; 1189 meters in elevation) 115% of normal (MFLNRO 2013).Observers noted the upper survey elevation of approximately 5000 feet based on the assessment of moose track presence. Weather conditions on January 4 th were clear and sunny with a temperature of -10C. Survey commenced five days since last snowfall (Environment Canada 2013). Survey conditions on February 12 th were overcast and cool with a temperature of -2C. Survey commenced one day after snowfall (Environment Canada 2013). Survey statistics A total of 249 moose were observed, including 74 bulls, 140 cows, 34 calves, and 1 unclassified (Table 1). Overall total survey time was 6.5 hours with a sighting rate of 38.6 moose per hour. The proportion of moose classified as juveniles was 13%. The naive population ratios were 52 bulls/100 cows (90% CI 38-67) and 24 calves/100 cows (90% CI: 17-31). Corrected ratios were 27 calves: 100 cows (90% CI: 22-40), and 47 adult bulls: 100 cows (90% CI: 34-60; Table 1). Results by LEH zone are also provided in Table 1. Historical moose compositional data is provided in Table 2. Moose observations and survey area are illustrated in figure 2. Table 1. Naive and corrected moose population composition for WMU 3-28 and for 3-28 LEH Zones A & B respectively. WMU/LEH zone Total Cows Bulls Calves Calves:100 cows (90%CI) Bulls:100 cows (90%CI) 3-28 Observed 249* ** (17-31) 52 (38-67) Estimated (22-40) 47 (34-60) Correction Factor A Observed (15-36) 79 (55-111) Estimated (18-45) 71(42-100) Correction Factor B Observed ( ) 33(22-65 ) Estimated (19-42) 29(20-63) Correction Factor *Includes one unclassified animal **Six bulls were classified as yearling but grouped with bulls for anylsis 7

9 Table 2. MU 3-28 Uncorrected sex and age ratios from post hunt surveys, DATE RATIO TOTAL COUNT BULL COW CALF Jan Jan 3, Dec 17, Jan 29, Jan 4 & Feb 12, SIGHTING RATE (MOOSE/HR.) Figure 2. Moose observations and flight path within WMU 3-28 LEH zones A & B (January and February 2013). Inset photo of respective burn habitat in LEH Zone A. 8

10 Wildlife Management Unit 3-31 Survey conditions The composition survey for WMU 3-31 was conducted on February 17 th, Snow cover was complete throughout the entire survey area. Weather conditions were cool and clear with temperatures fluctuating between -1C and -4C depending upon elevation. Observers noted the upper survey elevation of approximately 4900 feet based on observations of moose and their sign. Survey statistics A total of 145 moose were observed, including 34 bulls, 75 cows, 36 calves, and 1 unclassified (Table 3). Overall total survey time was 4.7 hours with a sighting rate of 30.9 moose per hour. The proportion of moose classified as juveniles was 24.8%. The naive population ratios were 45 bulls/100 cows (90% CI: 31-63) and 48 calves/100 cows (90% CI: 37-60). Corrected ratios were 46 calves: 100 cows (90% CI: 36-56), and 44 adult bulls: 100 cows (90% CI: 34-54; Table 3). Observers did not observe any wolf tracks or moose kills during the survey. Historical moose compositional data is provided in table 4. Moose observations are illustrated in figure 3. Table 3. Naive and corrected moose population composition for WMU 3-31, WMU Total Cows Bulls Calves Calves:100 cows (90%CI) Bulls:100 cows (90%CI) 3-31 Observed (37-60) 45 (31-63) Estimated (36-56) 44 (34-54) Correction Factor Table 4. Uncorrected sex-age ratios from post hunt surveys WMU 3-31, (NR- not recorded). DATE RATIO TOTAL COUNT SIGHTING RATE (MOOSE/HR.) BULL COW CALF NR NR NR NR NR NR NR NR

11 Figure 3. Moose observations and flight path within WMU 3-31 (February 2013). Inset photo: Wetland meadow habitat within WMU

12 Wildlife Management Unit 3-42 Survey conditions The composition survey for WMU 3-42 was conducted on January 3, Snow cover was complete throughout the entire survey area with snow pillar data measured at the Adams River manual snow station (1769 meters in elevation) at 104% of normal (MFLNRO 2013). Observers noted the upper survey elevation of approximately 3280 feet based on the assessment of moose track presence. Weather conditions were clear and sunny with ambient air temperature recorded as -12C. Survey statistics A total of 24 moose were observed, including 9 bulls, 13 cows, 2 calves, (Table 5). Overall total survey time was 3.1 hours with a sighting rate of 8.1 moose per hour. The proportion of moose classified as juveniles was 8.3%. The naive population ratios were 69 bulls/100 cows (90% CI: ) and 15 calves/100 cows (90% CI: 0-33). Corrected ratios were 12 calves: 100 cows (90% CI: 5-19), and 65 adult bulls: 100 cows (90% CI: 33-97; Table 5). Previous composition moose survey data is presented in table 6. Moose observations are illustrated in figure 4. Table 5. Naive and corrected moose population composition for WMU 3-42, WMU Total Cows Bulls Calves Calves:100 cows (90%CI) Bulls:100 cows (90%CI) 3-42 Observed (0-33) 69(29-144) Estimated (5-19) 65 (33-97) Correction Factor Table 6. Uncorrected sex-age ratios from post hunt surveys WMU 3-42, DATE RATIO TOTAL COUNT BULL COW CALF Feb 1, Jan 3, SIGHTING RATE (MOOSE/HR.) 11

13 Figure 4. Moose observations and flight path within WMU 3-42 (January 2013) 12

14 Wildlife Management Unit 3-36 Survey conditions The composition survey was conducted on February 14th, 2013 under overcast to partially cloudy conditions. Snow cover was complete throughout the entire survey area with southern portions of the WMU experiencing below normal snow levels, Anglemont manual snow station was recording 89% of normal (1168 meters in elevation; southern portion of WMU), and Kiberyville Lake (8km to the northeast; 1739 meters in elevation) recording 102% of normal (MFLNRO 2013). During the survey the ambient air temperature was stable between -1C and -4C. Observers noted the upper survey elevation of approximately 3300 feet based on observations of moose and their sign and suitable habitat. Survey statistics A total of 30 moose were observed, including 10 bulls, 17 cows, 3 calves, (Table 7). Overall total survey time was 4.72 hours with a sighting rate of 6.36 moose per hour. The proportion of moose classified as juveniles was 10%. The naive population ratios were 59 bulls/100 cows (90% CI: ) and 18 calves/100 cows (90% CI 5-36). Corrected ratios were 23 calves: 100 cows (90% CI: 2-44), and 59 adult bulls: 100 cows (90% CI: 26-92; Table 7). Moose observations are illustrated in figure 5. Table 7. Naive and corrected moose population composition for WMU WMU Total Cows Bulls Calves Calves:100 cows (90%CI) Bulls:100 cows (90%CI) 3-36 Observed (5-36) 59 (28-123) Estimated (2-44) 59 (26-92) Correction Factor

15 Figure 5. Moose observations and flight path within WMU 3-36 (February 2013). Inset photos: Scotch Creek Moose winter habitat and wolf pack of 5-6 animals observed near the Ratchford River confluence. 14

16 Discussion The annual acquisition of moose population composition data, or age/sex structure, is important to properly assess moose populations (Timmerman 1993). Provincial bull ratio targets of 30 bulls per 100 cows were met in all WMUs surveyed, as per the Moose Harvest Management Procedure (MFLNRO 2010). Weather conditions were considered good during the course of the survey window, e.g. complete snow cover and cool temperatures. Overall, survey results suggest moose age and sex structures appear to be influenced by habitat quality, predation rates and hunting regulations. Predation is suspected as the proximal cause of limiting moose populations within the North Thompson Game Management Zone (GMZ) (WMUs 3-36 and 3-42). In lieu of conducting a stratified random block survey, biologists cautiously estimate that moose populations within the North Thompson GMZ (WMUs 3-42 and 3-36) have declined by approximately 50%; previous population estimates were 250 and 300, respectively. Wildlife Management Unit 3-31 Comparison of previous moose sightability rates and population demographic data (Table 4) reveals a stable trend of high calf and bull ratios. This result is indicative of a stable population. The spatial distribution and abundance of important static wetlands and juxtaposition of forest cover, and reduced hunter access to prime wetlands, likely reduces moose vulnerability while promoting moose survival and reproduction. A calf ratio of approximately 30 calves/100 cows in harvested populations, depending on adult harvest and natural mortality rates, is generally required to maintain a stable population (Hatter and Bergeurd 1991). This threshold has been obtained in each of the respective post-hunt moose composition surveys. The low sightability rates of moose within the Clinton and fifty-seven Creek watersheds maybe a result of high snowpack that forced moose to leave higher elevation habitats. These watersheds typically feature higher densities of moose. Overall, juvenile recruitment and bull ratios within WMU 3-31 remain fairly robust suggesting neither forage, predation, or density dependant mechanisms are currently limiting factors within WMU Wildlife Management Unit 3-28 Results suggest bull ratios have increased in this unit from 26 bulls per 100 cows in 2009 to 47 bulls per 100 cows in We accredit this change to the adjustment in the spike-fork hunting season. To compensate for increased harvest of yearling spike fork bulls, due to increasing rates of road access and pine beetle salvage, the spike-fork season was shortened and shifted from September 20 th - October 31 st to October 15 th November 15 th. This change was designed to reduce hunting pressure when moose are vulnerable during the breeding period. Kill per unit effort also suggests bull numbers have increased from 1.6 moose /100 days in 2009 to 2.2 moose/100 days in 2011 (MFLNRO, unpublished data). Results also suggest recruitment rates are hovering around the threshold, despite the presence of high value foraging habitat due to the McLure fire and older forest development. Calf ratio of 24 calves per 100 cows is lower when compared to the regional average ( ) of 32 calves per 100 cows. This is likely a result of predation, as wolf occurrences are common within WMU 3-28 based on trapper effort and catch. Regionally, no specific inventory has been conducted for black bears (Ursus americanus) but based on other indicators, such as harvest statistics, we suspect black bear populations in the area are stable to increasing and they are known to be important predators of young calves (Schwartz and Franzmann 1991). 15

17 Wildlife Management Unit 3-36 The 2013 moose composition survey represents the first count formally conducted in WMU 3-36 and will serve as a baseline to monitor future trends in distribution and abundance. The low sightability rate of 6.4 moose per hour, compared to the regional average of 32 moose per hour (MFLNRO, unpublished data) suggests moose are at a lower density within WMU Although population trend information from aerial surveys is lacking, hunter sample data denotes a decline in kill per 100 days, from 2.9 moose/100 days in 2009 to 0.5 moose/100 days in 2011, indicating a population decline. The stark decline of hunter moose kills, even with an increase in total hunter days in 2011 of 1130 up from 669 in 2010, provides additional evidence that the moose population has declined in WMU This decline appears to mirror the estimated 60% population reduction in WMUs 3-43 and 3-44 derived from block counts conducted in 2013 (Procter and Iredale 2013). The primary cause of this decline is attributed to wolf predation. We noted one pack of six animals near the confluence of the Ratchford River and had observations of moose kills and wolf sign in other areas within the WMU (e.g., Humamilt Lake area). Observers failed to detect moose within the northern portion of the Seymour River despite the presence of suitable wetland habitats. Snow conditions were considered normal, although slightly above normal within the northern portion of the management unit. However, snow conditions did not appear to be beyond moose tolerance levels within the north portion of the survey. Incidental moose observations attained during winter range reconnaissance surveys confirm moose have occupied these northern wetlands. An early season higher snowpack may have forced moose to move south to areas of lower snowpack. Wildlife Management Unit 3-42 The sightability rate of 8.1 moose per hour within WMU 3-42 and observed lower moose densities and distribution suggests the moose population has declined. Observers noted half the number of moose present within this management unit compared to the 2005 composition tally of 52 moose. Hunter sample data provides further support that the moose population within WMU 3-42 has declined. The hunter kill per unit effort has declined from 1.7 moose per 100 hunter days in 2008, to 0 moose per 100 days for respectively. As with WMU 3-36, high wolf predation rates are suspected as the primary cause. Regional biologists have estimated a continued increase in wolf numbers within the Thompson Region since Wolf pack monitoring conducted in 2009 by Jury and Procter as part of the Mountain Caribou recovery initiative estimated an approximate population of wolves within Using the previous population estimate of 250 moose this results in an estimated 11 moose per wolf ratio. Based upon incidental observations during aerial surveys wolf numbers appear to have declined within the North Thompson. Wolf sign was observed near Tumtum Lake (3-5 animals) and near Mica Lake (3-5 animals). Animals appeared to be using heaver security cover as observers noted an additional 25 sets of tracks without actually visualizing the moose. This may be an anti-predator response. Conclusion The moose reconnaissance level compositional surveys are a necessary part of monitoring local populations of highly utilized species, such as moose, in order to assess population trends and composition, recruitment, distribution and to set quota for the next subsequent hunting season. Current harvest levels for moose within WMUs 3-42 and 3-36 need to be adjusted to account for high rates of predation. An increase in LEH bull opportunities is warranted for WMU 3-28 to account for higher bull 16

18 sex ratios. Predation is the proximal cause of mortality for moose populations within the North Thompson GMZ. Recommendations Adjust annual allowable harvest (AHH) and lower harvest rate (6% 4%) with WMUs 3-36 and 3-42 due to low recruitment rates as a result of wolf predation. Reduce LEH antlerless harvests within WMUs 3-36 and Increase LEH bull opportunities within WMU Periodic inventory of moose populations are a necessary part of the management of this highly utilized species and are ideally carried out every 3 to 5 years. Acknowledgements The authors extend their gratitude to Kevin Jackson of CC Helicopters and Kelly Croswell of Frontline Helicopters for providing safe and efficient helicopter services. Thanks also goes to John Surgenor (MFLNRO), Warren Chayer (Conservation Officer), Austin Lord, Mel Crombie (UVic), Dennis Jelinksi (UVic) and Larry Gardener (Environmental Protection) for volunteering to be a secondary observer during moose composition surveys. We thank Andrew Walker (MFLNRO) for his review and comments. Literature Cited Demarchi, D An introduction to Ecoregions of British Columbia. Ecosystem Information Section Knowledge Management Branch Ministry of Environment. Victoria, British Columbia. Accessed: March 12, 1013: Environment Canada Historical Climate Data. Accessed July Hatter, I.W. and W.A. Bergerud Moose recruitment, adult mortality and rate of change. Alces 27:65-73pp. Ministry of Forests, Lands and Natural Resource Operations Moose Harvest Management Procedure Manual. Prepared for the Ministry of Environment. 6pp. Ministry of Forests, Lands and Natural Resources Operations Automated Snow Pillar Data. Accessed March 13, 2013: Procter. C., and F.Iredale North Thompson River Block Survey Management Units 3-43 and In prep. Ministry of Forests, Lands and Natural Resource Operations. Kamloops, BC. Quayle, J.F., A.G. MacHutchon, and D.N.Jury Modeling moose sightability in south-central British Columbia. Alces 37:43-54pp. Schwartz, C. and A.Franzmann Interrelationship of Black Bears to Moose and Forest Succession in the northern Coniferious Forest. Wildl. Monogr. 113:1-58 Timmerman, H.R Use of aerial surveys for estimating and monitoring moose populations- a review. Alces 29:

19 Unsworth, J. W., F. A. Leboan, E. O. Garton, D. J. Leptich, and P. Zager Aerial survey: user s manual. Electronic edition. Idaho Department of Fish and Game, Boise, Idaho. Photo: J.Hobbs 18