Seventy-nine radiocollared cows ages 2 years and older were observed during flights on 2 - 4 June (Fig. 4).
Parturition rate (percent of cows that were pregnant or had given birth) was 88% for cows 4 years of age or older (n = 67).
Four 3-year-old cows were observed, and all were seen with calves. All 2-year-old cows (n = 8) were barren. Of the 71 cows that were less than 3 years old, 50 were observed with calves, 13 were judged to be pregnant or to have produced and lost a calf (based on presence of hard antlers and enlarged udders), and 8 were judged to be barren (no hard antlers and udders not distended). All 21 parturient cows observed on 2 June and 23 of 26 observed on 3 June were accompanied by calves. Many calves appeared to be several days old, based on size and mobility.
Thus, the peak of calving was probably about 30 May.
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During 2–4 June, 5 radiocollared cows were within the boundaries of the Arctic National Wildlife Refuge, and none were inside the 1002 area. All 5 cows were parturient (4 were seen with a calves on 2–3 June and 1 was still pregnant on 4 June). By 18–19 June, most of the herd had moved into the Refuge. FWS tracking flights on these dates located 97 caribou (84 cows; 13 bulls), of which 84 (87%) were in the Refuge. These caribou were mostly in the Brooks Range foothills, extending from the Jago River eastward into northern Yukon.
Low clouds and fog prevented flight over some hills where caribou were known to be on 22.23 June. Thus, 2 barren cows and 10 parturient cows that were seen in early June were either not located (n = 8) or not observed (n = 4, including 2 located by satellite tracking) on 22-23 June. All 63 cows for which locations were known were inside the Arctic National Wildlife Refuge, and 16 (25%) were within the 1002 area at this time. Fifty-nine cows were actually observed on these dates (Fig. 5).
Seventy-three percent (73%) of radiocollared cows at least 4 years old (n = 56) were accompanied by a live calf during the postcalving flights.
Estimates of calf production and survival during June 2007 are among the highest recorded for this herd.
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Weather on the coastal plain was sunny and warm (approximately 20 C) on 21 June. Temperatures then dropped significantly as a cold front moved through the area on 22–23 June. Several days of cool, cloudy weather followed, and as a result, much of the herd moved south into the Brooks Range. Warm, sunny weather returned on 29–30 June, causing caribou to aggregate in groups scattered from the northern foothills near the Jago River south and east to headwaters of the Colleen River.
A photocensus was conducted on 1 July. Results will be described in a future report
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How many of the satellite collared cows had calves?
Fifteen caribou cows were also monitored by satellite tracking at 2-day intervals. (Note: the satellite transmitters give the general location, but the radio-transmitter is needed to actually find the animal).
Of these, Arnaq, Catherine, Claudia, Cocoa, Daphey, Helen, Kate, Pingo, Rocky, Tundra, and Waldo were seen with calves in early June, Sprig was pregnant on 3 June and seen with a calf on 22 June.
Belle, Bertha, and Donner were judged to be barren.
Waldo and Claudia were not observed in late June, but the 9 other parturient cows were accompanied by calves at that time.
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Below is a summary of all caribou and information on whether or not they calved the past 10 years.
Note: -- means that the caribou was not located
If you have any questions, please contact:
Dorothy Cooley or Martin Kienzler
Regional Management
Box 600
Dawson City, YT
Y0B 1G0
Phone (867) 993 6461
Fax (867) 993 6548
Email dorothy.cooley@gov.yk.ca or
martin.kienzler@gov.yk.ca
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