USE OF NIGHT SPOTLIGHTING FOR ESTIMATING WHITE-TAILED DEER POPULATION TRENDS IN THE PEND D’OREILLE VALLEY

Prepared by:

John C. Gwilliam and John A. Krebs Columbia Basin Fish and Wildlife Compensation Program

103 – 333 Victoria Street Nelson, BC V1L 4K3

www.cbfishwildlife.org

April 2006

Table of Contents

Table of Contents .................................................................................................................... i Lists of Tables and Figures ....................................................................................................... i Abstract .....................................................................................................................................1 Introduction................................................................................................................................1 Study Area .................................................................................................................................1 Methods......................................................................................................................................4 Results .......................................................................................................................................4 Discussion and Management Implications ................................................................................7 Acknowledgements....................................................................................................................8 Literature Sited...........................................................................................................................8 List of Tables and Figures Table 1 - Average number of white-tailed deer/km (±SE) and maximum (peak) number of white-tailed deer counted in the Pend d’Oreille valley from 1998 - 2005 ............................5 Figure 1 - Overview Map...........................................................................................................2 Figure 2 - Pend d’Oreille White-tailed Deer Spotlight Transect ...............................................3 Figure 3 - Average number of white-tailed deer/km recorded on peak and all counts in the Pend d’Oreille valley from 1998 - 2005 ..........................................................................5 Figure 4 - Number of white-tailed deer observed in 1998 on the series of Pend d’Oreille spotlight counts..................................................................................................6 Figure 5 - Number of white-tailed deer observed in 2004 on the series of Pend d’Oreille spotlight counts..................................................................................................6 Figure 6 - Correlation between Pend d’Oreille valley fecal pellet group and spotlight counts, 1980 – 2007 ...................................................................................................................7

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ABSTRACT White-tailed deer spotlight and fecal pellet counts were conducted annually in the Pend d’Oreille valley in late March through mid-April for the years 1980 – 2005. Because of the strong correlation between the spotlight and pellet group counts, only the spotlight counts were continued after 1998. Spotlight counts conducted when white-tailed deer are concentrated on low elevation spring ranges in the Pend d’Oreille valley appear to provide an effective, cost effective method of estimating annual changes in population size. INTRODUCTION Night spotlighting is a technique that has been used frequently to detect presence and provide estimates of deer populations (McCullough 1982, Fafarman and DeYoung 1986, Cypher 1991, Whipple et al. 1994, cited from Belant and Seamans 2000). In British Columbia, nightcounts have been used to monitor changes in seasonal dispersion and use of certain habitats by black-tailed deer (Odocoileus hemionus columbianus) (Jones 1975, Harestad 1979) and annual changes in deer abundance (Harestad and Jones 1981, Jones and Mason 1983). Spotlighting also has been used to study red fox (Vulpes vulpes) abundance (Sharp et al. 2001), European rabbit (Oryctolagus cuniculus) growth rates (Caley and Morley 2002), and raccoon (Procyon lotor) long-term population trends (Gehert et al. 2002). Relative numbers of white-tailed deer inhabiting the Pend d’Oreille valley of British Columbia was estimated in the 1980’s and 1990’s using fecal pellet group and night spotlight counts (Boulanger 2000). Because pellet group counts require substantial effort to annually count and clear the pellet plots they were discontinued after 1997. Spotlight counts were continued after 1997 to 2005 because of their low cost, ease of use, and comparability of data collected from other types of population monitoring. This report summarizes the results recorded on a series of Pend d’Oreille valley (POV) spotlight counts conducted by the Columbia Basin Fish and Wildlife Compensation Program (CBFWCP) from 1998 to 2005 where the peak count and the number of deer/km provided indexes of white-tailed deer population abundance. Recommendations on future use of spotlight counts in the Pend d’Oreille are also provided. STUDY AREA Spotlight counts were conducted in West Kootenay in the western part of the POV near Waneta, British Columbia, between the Columbia River and Charbonneau Creek (Figures 1 & 2). The climate of the area is transitional between wetter temperate coastal and drier continental weather patterns. Mean July and January temperatures for Waneta, located on the valley bottom at the west end of the study area, are 19.7 and –4.8ºC, respectively (Vold et al. 1980). Annual precipitation at Waneta averages 630 mm, with 180 cm falling as snow; total precipitation within the valley increases from west to east and with increasing elevation (Vold et al. 1980). Snow often persists on the valley floor from

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Figure 2: Pend d’Oreille White-tailed DeerSpotlight Transect

March 9, 2006

5.2 Historic Transect Distances (miles)Based on a vehicle odometer

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early or mid-December to mid-March, but during mild winters low elevation south-facing slopes may be snow-free for periods during mid-winter. The study area encompassed southern aspects and relatively steep slopes on the north side of the Pend d’Oreille River. Elevations ranged from 470m along the Pend d’Oreille River to 1,410m at the upper extent of the winter range; upslope peaks extended to 1,850m. Biogeoclimatic subzones in the area include the Interior Cedar Hemlock xeric, warm (ICHxw) at valley bottom, the dry, warm (ICHdw) at lower to mid-elevation slopes, and moist, warm (ICHmw2) at midslope (Braumandl and Curran 1992). The entire spotlight count transect is located within the ICHxw subzone. Douglas-fir (Pseudotsuga menziesii) commonly dominate southern exposures, much of it in even-aged stands that resulted from a major fire in the 1890’s (Vold et al. 1980, Woods 1984). Shrub or grass communities with open Douglas-fir or ponderosa pine (Pinus ponderosa) stands occupy steep south aspects that have historically been influenced by fire. Dominant habitats found along the transect were active and abandoned agricultural land, pasture, open grassy side hills, shrub, Douglas-fir forest, and disturbed areas. Land use activities include hydroelectric development, agriculture and forestry and wildlife-based and water-oriented outdoor recreation. METHODS POV spotlight counts were conducted from 1998 through to 2005 where a fixed route of 18.7 km was driven from late March through mid-April when white-tailed deer were concentrated on spring ranges. Spring ranges in the POV consisted primarily of agricultural land and abandoned pasture. Spotlighting began just after darkness fell and lasted from 2 to 3 hours, depending upon the number of deer seen. When snow or fog occasionally completely obscured visibility the count was discontinued and rescheduled. At the beginning of the count weather conditions were recorded, including cloud cover, general air temperature, and whether or not precipitation was occurring. One observer spotlighted the area along the route from a 4X4 pick-up truck travelling at 5-20km/hour, this depending on visibility or road conditions. A 12-volt, 200,000 candlepower (approximately) spotlight was held outside the truck and the beam was shone over areas adjacent to the road in a sweeping motion. When deer were spotted, the vehicle was stopped and the deer were identified as to group size, sex, and age. Marked deer were also noted. The point (in kms) along the transect where the deer was located and habitat type were recorded as well. Other wildlife species (eg. elk, coyote, black bear, cougar) seen were also recorded. Where a large group of deer was sighted the horn was tapped to allow a more accurate count. When the observer was unsure of the species sighted, the animal was observed with 10X50 binoculars. RESULTS The number of white-tailed deer/km observed on the peak spotlight count varied from a high of 8.6 in 1999 to a low of 6.1 in 2005 (Figure 3). The average number of deer/km

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observed on all the spotlight counts varied from a high of 7.4 in 1999 to a low of 4.5 in 2005 (Figure 3 and Table 1). The peak counts ranged from a high of 160 in 1999 to a low of 114 in 2005 (Table 1). Table 1. Average number of white-tailed deer/km (±SE) and maximum (peak) number of white-tailed deer counted in the Pend d’Oreille valley from 1998 - 2005. 1998 1999 2000 2001 2002 2003 2004 2005 Average number of DEWT/KM

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Figure 5. Number of white-tailed deer observed in 2004 on the series of Pend d’Oreille spotlight counts. Deer numbers calculated from pellet group data were strongly correlated (t =23.62, p<0.0001) with peak night counts in spring (Figure 6). Using data from Figure 6 the estimated over-wintering white-tailed deer population in the Pend d’Oreille was determined as 1,163 deer.

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Figure 6. Correlation between Pend d’Oreille valley fecal pellet group and spotlight counts, 1980 – 2007. DISCUSSION and MANAGEMENT IMPLICATIONS Spotlight counts conducted over the fixed Pend d’Oreille route during March and April appear to provide rough estimators of white-tailed deer population trend. The data collected suggested that the number of white-tailed deer wintering in the Pend d’Oreille declined from 1999 through 2005 despite moderate winters over the last several years. Currently the number of white-tailed deer wintering in the Pend d’Oreille valley is less than half of what it was in the early 1990’s as reported by Boulanger et al. (2000). The decline in observations may be partially explained by a lighter snowpack in 2004 and 2005 allowing deer populations to be more widely distributed. Therefore there was potential for lower numbers of whitetails to be observed along the spotlight count transect. However, the deer decline is supported by a provincial hunter data showing whitetail buck harvest for management unit 4-08 has not rebounded to the levels recorded prior to the severe 1996/97 winter (Guy Woods, pers. comm.). Spotlight counts are more useful when carried out in conjunction with some other type of ungulate population monitoring in the same area. The ungulate aerial surveys conducted in 2000 and 2004 were not reliably comparable due to substantially increased surveying time in 2004 (Robinson et al. 2005). It is anticipated that a 2007 ungulate survey should be directly comparable to the 2004 survey and therefore more reliably comparable to the spotlight counts. The main advantage of the Pend d’Oreille white-tailed deer spotlight counts is that a large area was sampled with relatively modest effort (approximately 5 hours/survey including travel time to and from Nelson). Another major advantage is the availability of a large amount of open habitat adjacent to roads where deer concentrate in the spring that has remained virtually unchanged by habitat succession. A disadvantage is that in years with

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moderate winters not all the white-tailed deer migrate to the Pend Oreille valley. Also, in these same years some deer leave the valley prior to green-up when the lower elevations of nearby transitional ranges are snow free and greening-up over the same time period as the winter range. This was the case in 2004 and 2005 and potentially 2006. The strong correlation between the pellet group and spotlight counts was another major advantage. This supported the decision in 1997 to discontinue the more costly pellet group survey while continuing with the spotlight counts. With regards to future direction, the annual series of Pend d’Oreille spotlight counts should be conducted in 2006 and 2007 and the results compared to the 2007 ungulate aerial survey planned by CBFWCP for the Kootenay Wildlife Management Units 4-08 and 4-09. ACKNOWLEDGEMENTS Columbia Basin Fish and Wildlife Compensation Program funded the spotlight counts from 1980 to 2005 and fecal pellet group counts from 1980 to 1997. Ross Clarke provided editorial comments. Beth Woodbridge provided administrative support. LITERATURE CITED Boulanger, J.G., K.G. Poole, J. Gwilliam, G.P. Woods, J. Krebs, and I. Parfitt. 2000. Winter habitat selection by white-tailed deer in the Pend d’Oreille valley, southeastern British Columbia. Columbia Basin Fish and Wildlife Compensation Program. Nelson, B.C. 47pp. Braumandl, T.F. and M.P. Curran. 1992. A field guide for site identification and interpretation for the Nelson Forest Region. B.C. Ministry of Forests, Nelson, B.C. 312pp. Belant, J.L. and T.W. Seamans. 2000. Comparison of 3 devices to observe white-tailed deer at night. Wildlife Society Bulletin 28(1):154-158. Caley, P.A. and C.G. Morley. 2002. Assessing growth rates of European rabbit populations using spotlight transect counts. Journal of Wildlife Management 66:131-137 Cyhper, B.L. 1991. A technique to improve spotlight observations of deer. Wildlife Society Bulletin 19:391- 393. Fafarman, K.R. and C.A. DeYoung. 1986. Evaluation of spotlight observations of deer. Wildlife Society Bulletin 14:180-185. Harestad, A.S. 1979. Seasonal movements of black-tailed deer on northern Vancouver Island. PhD. Thesis, University of B.C., Vancouver. 184pp.

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Harestad, A.S. and G.W. Jones. 1981. Use of nightcounts for censusing black-tailed deer on Vancouver Island. Pages 83-96 in F.W. Miller, and A. Gunn, eds. Proceedings of the symposium on census and inventory methods for populations and habitats. Northwest Section Wildlife Society. Banff, Alberta. 202pp. Gehert, S.D., G.F. Hubert, and J.A. Ellis. 2002. Long-term population trends of raccoons in Illinois. Wildlife Society Bulletin 30(2):457-463. Jones, G.W. 1975. Aspects of winter ecology of black-tailed deer (Odocoileus hemionus columbianus Richardson) on northern Vancouver Island. MSc. Thesis, University of B.C., Vancouver. 78pp. Jones, G.W. and B. Mason. 1983. Relationships among wolves, hunting, and populations trends of black-tailed deer in the Nimpkish Valley on Vancouver Island. B.C. Fish and Wildlife Report No. R-7, Victoria. 26pp. McCullough, D.R. 1982. Evaluation of night spotlighting as a deer study technique. Journal of Wildlife Management 46(4):963-973. Robinson, H.S., J.C. Gwilliam, and R. Clarke. 2005. Mule deer and white-tailed deer abundance and population growth in southern British Columbia. Columbia Basin Fish and Wildlife Compensation report. Nelson, B.C. 57pp. Sharp, A., M. Norton, A. Marks, and K. Holmes. 2001. An evaluation of two indices of red fox (Vulpes vulpes) abundance in an arid environment. Society of Wildlife Research 28(4):419-424. Vold, T., R.F. Ferster, T.K. Ovanin, R.D. Marsh, and G.P. Woods. 1980. Soil and vegetation resources of the Pend d’Oreille valley, B.C. Assessment and Planning Division Bulletin 2, B.C. Ministry of Environment, Victoria, B.C., Canada. Whipple, J.D., D. Rollins, and W.H. Schacht. 1994. A field simulation for assessing accuracy of spotlight deer surveys. Wildlife Society Bulletin 22:667-673. Woods, G.P. 1983. Pend d’Oreille wildlife management plan. Fish and Wildlife Branch, B.C. Ministry of Environment, Nelson, B.C., Canada

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