Satellite Collaring and Calf Survival in the Bathurst Herd of Barren-Ground Caribou 2003-2005
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Satellite Collaring and Calf Survival in the Bathurst Herd of Barren-ground Caribou 2003-2005 Anne Gunn Environment and Natural Resources Government of the Northwest Territories 2013 Manuscript Report No. 228 The contents of this paper are the sole responsibility of the author. ii iii ABSTRACT The co-management plan for the Bathurst herd of barren-ground caribou (Rangifer tarandus groenlandicus) requires monitoring calf survival, movements and seasonal distribution. To monitor movements and seasonal distribution, Environment and Natural Resources (ENR) tries to maintain between 10 and 20 satellite collars on cows. In March 2003, ten cows were fit with satellite collars that had automatic drop-offs programmed for 15 September 2004. In October 2004, we flew reconnaissance surveys before capturing and fitting ten barren-ground caribou with satellite collars. In March 2005 we aimed to collar a further ten Bathurst cows and ten cows from the Ahiak herd. After fixed-wing reconnaissance flights to cover the possible winter ranges of the Bathurst and neighbouring herds (Bluenose-East, Bluenose-West, Cape Bathurst and Ahiak), we spread the capture and collaring of ten caribou from the Lac Grandin area southeast to Gordon Lake. We also caught and collared five cows at Nonacho Lake and five east of Artillery Lake. Based on the distribution of the collared cows in June 2005, we assigned the satellite collared cows to different herds based on their return to traditional calving grounds. From the distribution of collared cows, in June 2005, the distribution of the Bathurst and Bluenose-East herds overlapped in the area of Lac Grandin north to Great Bear Lake. Also Ahiak herd and Bathurst herd overlapped their winter ranges at Nonacho Lake. Measured calf-cow ratios were low (mean was 14 calves:100 cows) which is consistent with the poor calf survival during summer 2004. Extrapolated summer temperatures and wind were used to develop an index of insect harassment severity. Information from hunter harvest samples revealed that pregnancy rates were low to moderate across the winter range in March 2005. If the lower than average pregnancy rate and low calf survival persist, the Bathurst herd is unlikely to reverse its current decline in abundance. iv TABLE OF CONTENTS ABSTRACT .................................................................................................................... iii LIST OF FIGURES ......................................................................................................... vi LIST OF TABLES ........................................................................................................... vi INTRODUCTION ............................................................................................................. 1 METHODS ...................................................................................................................... 5 Pregnancy rates June 2004: ..................................................................................... 5 Pregnancy rates winter 2004-05: .............................................................................. 5 Collaring: .................................................................................................................. 5 Calf survival April 2005: ............................................................................................ 5 Insect harassment index: ......................................................................................... 6 Statistical Analyses ...................................................................................................... 8 RESULTS ....................................................................................................................... 9 Collaring March 2003: .............................................................................................. 9 Pregnancy rates June 2004: ................................................................................... 10 Collaring October 2004: ......................................................................................... 11 Collaring March 2005: ............................................................................................ 12 Calf survival April 2005: .......................................................................................... 15 Caribou Condition: ................................................................................................. 17 Insect harassment: ................................................................................................. 20 DISCUSSION ................................................................................................................ 23 ACKNOWLEDGEMENTS.............................................................................................. 30 PERSONAL COMMUNICATIONS ................................................................................. 31 LITERATURE CITED .................................................................................................... 32 APPENDIX A: Summary of 1998-2000 Satellite Collars on Bluenose-East Caribou Herd. ...................................................................................................................................... 34 Introduction: ............................................................................................................... 34 APPENDIX B: Caribou Collaring Capture Details for March 2005 and October 2004. ... 36 March 2005................................................................................................................ 36 APPENDIX C: Sex and Age Composition of Caribou from the Bathurst Herd, March 2005, NWT. ................................................................................................................... 37 APPENDIX D: Sex and Age Classes and Antler Status for Caribou Classified 23-26 June, 2005. ................................................................................................................... 46 APPENDIX E: Physical Condition and Measurements for Caribou Harvested January- April 2005, Bathurst Herd Winter Ranges, NWT. (Data from Earl and Trevor Evans, Fort Smith, NWT) ................................................................................................................. 49 v APPENDIX F: A Weather-Related Index to Mosquito and Warble Fly Abundance for the Post Calving and Summer Range of the Bathurst Herd, NWT, 1957-2005 (Service Contract 781079 to John Lee). ...................................................................................... 57 vi LIST OF FIGURES Figure 1: Study area for spring and fall collaring and sex age composition surveys conducted on the Bathurst caribou range, Northwest Territories, 2003-2005. ................. 3 Figure 2: Locations for the pre-2003 collars and the 2003 collar deployments, 23 March, 2003, NWT and Nunavut. .............................................................................................. 10 Figure 3: Flight lines for aerial reconnaissance and collaring locations, NWT, October 2004. ............................................................................................................................. 12 Figure 4: Flight lines, caribou observations, location 2004 satellite collars and collaring locations during March 2005, NWT. .............................................................................. 13 Figure 5: Flight lines and locations for sex and age composition counts in the Bathurst caribou herd, March 2005, NWT.................................................................................... 16 Figure 6: Calf:cow ratios in four areas sampled across the winter range of the Bathurst herd, March 2005, NWT. ............................................................................................... 17 Figure 7: Categories of warble larvae (high, medium, and low) found on caribou harvested on the central western parts of the Bathurst herd’s winter range January-April, 2005. ............................................................................................................................. 19 Figure 8: Seasonal distribution of seasonal mosquito and osterid abundance index for the years 1996 to 2005. ................................................................................................. 20 Figure 9: Annual osterid intensity scores for the area around Lupin, NWT based on an index derived from temperature and wind speed records from, 1957 to 2005. ............... 21 Figure 10: Annual mosquito intensity scores for the area around Lupin, NWT based on an index derived from temperature and wind speed records from, 1957 to 2005. .......... 21 Figure 11: Locations of collared caribou from the Qamanirjuaq, Wager Bay and Lorillard River herds and caribou sightings during reconnaissance flights March, 2005 (data from Mitch Campbell, Government of Nunavut). .................................................................... 25 Figure 12: Calf cow ratios and their confidence intervals regressed against year for the Bathurst herd 1985-2005. .............................................................................................. 26 Figure 13: Trend line and annual scores for mosquito and oestrid fly harassment (scored as 1 for Low, 2 for Moderate and 3 for High) based on 1957-2005 weather records for Contwoyto Lake, NU.................................................................................... 28 LIST OF TABLES Table 1: Dates, sampling effort and wolf sightings for monitoring calf