Bighorn Sheep Surveys of Know Winter Ranges
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Bighorn Sheep Survey of Known Winter Ranges in the Canmore area of the Southern Rockies Area, 2008 by Jon T. Jorgenson Senior Wildlife Biologist Canmore and Michael Jokinen Biologist Alberta Conservation Association Blairmore May 20, 2008 Alberta Sustainable Resource Development Fish and Wildlife Division Canmore PERMISSION TO QUOTE This report contains preliminary surveys results and interpretations that may be subject to future revisions. To prevent the issuance of misleading information, persons must first obtain permission from the Area Manager of the Southern Rockies Area or the Director of the Wildlife before quoting from this report, citing in bibliographies or using it in any other possible form. ACKNOWLEDGEMENTS The authors would like to thank P. Young, and J. Wieliczko for assistance as observers during the 2008 survey. Alpine Helicopters provided the pilots and aircraft for the survey period. ABSTRACT A bighorn sheep survey was conducted on January 20, 21, 23, and 24, 2008 on 14 of 22 known winter ranges within Wildlife Management Units (WMU’s) 404, 406, 408, 410, and 648 (Peter Lougheed Provincial Park). Weather conditions were excellent with fresh snow, clear skies and calm winds. A total of 15 hours of helicopter time including deadheading time was used. Elk surveys were conducted at the same time because many sheep wintering areas are found near elk wintering habitats. A total of 824 sheep were observed, consisting of 430 ewes, 147 lambs, 43-1/4 curl rams, 53-1/2 curl rams, 94-3/4 curl rams, 37-4/5+ curl rams, and 20 unclassified sheep. Total sheep numbers appear comparable to previous surveys when similar areas were able to be covered and considering that winter ranges north of the Bow River were not surveyed in 2008, the 2008 count was at the high end. Lamb: ewe ratios were at the low end of the range (31%) relative to the long-term average but they were not alarmingly low. Considerable variation was found when counts were compared within WMU’s over time. Both WMU 404 and 406 are up slightly in total numbers while WMU 408 is lower than earlier surveys. Downward trends in total count were evident for the Three Sisters-Wind Ridge and Sheep river winter ranges. Sheep numbers in WMU 410 were the highest observed, however, caution is advised in interpretation due to the possibility of duplicate counts during the ground surveys conducted along Highway 1A. ii TABLE OF CONTENTS INTRODUCTION .......................................................................................................................... 1 STUDY AREA AND METHODS ................................................................................................. 1 RESULTS AND DISCUSSION..................................................................................................... 5 LIST OF TABLES Table 1. Total count, age/sex composition of bighorn sheep observed during aerial surveys, 1973-2008 ....................................................................................................................................... 7 Table 2. Results by WMU from aerial surveys of bighorn sheep winter ranges, 1973-2008........ 8 Table 3. Lamb/ewe ratios observed in each of the major WMU’s, 1973-2008............................. 9 Table 4. Counts of sheep observed in each of the sub-units where non-trophy sheep permits are allocated, 1973-2008..................................................................................................................... 10 Table 5. Summaries of sheep observed by winter range and WMU during aerial and/or ground surveys, 1973-2008....................................................................................................................... 11 Table 6. Highway 1A (WMU 410) bighorn sheep observations ................................................. 20 LIST OF FIGURES Figure 1. Sheep winter ranges in vicinity of the Ghost Wilderness Area...................................... 2 Figure 2. Sheep winter ranges within the Kananaskis valley area................................................. 3 Figure 3. Sheep winter ranges in vicinity of the Highwood and Plateau Mountain areas............. 4 LIST OF APPENDICES Appendix 1. WMU observation checkpoints and group composition data for 2008................... 21 Appendix 2. Bighorn sheep observation locations during the 2008 winter aerial survey ........... 23 iii INTRODUCTION In 1973, a systematic winter aerial survey for bighorn sheep was initiated in the Canmore area of southwest Alberta. Since this time, repeated surveys have been conducted over the same areas in order to monitor the spatial distribution, post-hunt herd composition and to monitor trends in the number of bighorn sheep at the population level, in each of the Wildlife Managements Units (WMU) and at the winter range scale. The acquired information is used to support wildlife management recommendations related to land-use decisions and hunting regimes. STUDY AREA AND METHODS The study area encompasses the eastern slopes of southern Alberta from the Ghost River Wilderness Area in the north to Plateau Mountain at the southern boundary of Kananaskis Country. There are 22 sheep winter ranges identified within this area and it is these winter ranges that are surveyed (Figures 1, 2, and 3). 1 Figure 1. Sheep winter ranges in vicinity of the Ghost Wilderness Area 2 Figure 2. Sheep winter ranges within the Kananaskis valley area 3 Figure 3. Sheep winter ranges in vicinity of the Highwood and Plateau Mountain areas 4 Winter ranges are represented in all 8 WMU’s: 404, 406, 648 (Peter Lougheed Provincial Park), 408, 410, 412, 414 and 734 (Ghost Wilderness Area). Most of the winter ranges in WMU 410 are no longer surveyed due to the difficulty of finding sheep on a reliable basis. These areas instead are surveyed in the spring from the ground along Highway 1A where these sheep congregate during winter and spring. These ground survey counts are included in this report. The Sheep River herd in WMU 406 is also a winter range that is not always aerial surveyed. This herd has been intensively studied for several years using marked animals. The Sheep River herd’s status is closely known and there is no need to survey it from the air. All ground counts of marked sheep are incorporated in this report. A Bell 206 Jet Ranger helicopter was used for these surveys employing a navigator/observer in the front and two observers in the back. The pilot was also participating to the survey as an observer. Sheep sightings were logged on a 1:250 000 topographic scale map and a hand held Garmin GPS unit was utilized to record UTM coordinates of each observation location point. Graphics listing all observation points within the surveyed areas were created in ArcGIS 9.2 (Appendix 1). Fresh tracks were easily observed, eliminating the need to search every valley and, consequently, reducing exploring time. Each winter range was flown slightly above tree line and at higher elevations covering mountain ridges and cliffs. Canon Image Stabilizer binoculars were employed to aid the classification of sheep into one the following cohorts: ewes, lambs and rams at 1/4 curl, 1/2 curl, 3/4 curl, and 4/5 curl (trophy). Yearling ewes and rams are hard to differentiate from the air and generally are grouped with the ewe cohort. Additional sheep are occasionally found outside traditional winter range boundaries. Thus, they were not included in the totals of conventional winter range. All pertinent data was recorded onto survey sheets and was later condensed into table format (Appendix 2). This survey was also done in conjunction with the Canmore/Calgary area elk survey, hence observations of elk were also recorded in addition to incidental mountain goats observations. RESULTS AND DISCUSSION The bighorn sheep survey was flown at the same time as the elk survey, therefore sheep observations were scattered over a span of several days, ensuring all sheep and elk winter ranges were surveyed. Aerial observations for sheep were conducted on January 20, 21, 23, and 24th, 2008. Total flight hours used to cover the sheep winter ranges was approximately 15 hours 5 including deadheading back and forth from fuel caches and pick-up points. During these surveys, flying and observing conditions were good to excellent with sunshine, calm winds and mostly recent snowfall. We were unable to survey winter ranges north of the Bow River, due to a loss of snow cover and resultant poor surveying conditions. Appropriate survey conditions did not occur for the rest of the surveying season, therefore WMU’s 412, 414, and 734 (Ghost Wilderness Area) were not surveyed in 2008. A total of 824 bighorn sheep were observed during 2008 (Table 1). Comparisons with other survey years are difficult because it has been difficult to complete the surveys for all winter ranges during each survey attempt. Loss of snow cover before the entire survey can be completed has been a common problem in recent years. Considering that the 2008 survey did not include any winter ranges north of the Bow River, the count of 824 is at the high end of the range for counts from previous years and is indicative of a fairly stable population compared with counts from the early 1970’s. Over 99% of the sheep observed in 2008 could be classified for a total group composition that consisted of 28% rams, 54% ewes, and 18% lambs (Table 1). The percentage of trophy rams in the population was 5% which is consistent with previous surveys. The lambs/100 ewe ratio was 34, at the low end of the range of values from