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Contents: Calving Update 2009 How many of the satellite collared cows had calves? Download the memorandum by Jason Caikoski of the Alaska Department of Fish and
Game
For the second consecutive year the majority of the Porcupine Caribou Herd wintered in Alaska. From October 2008 to March 2009, 13 of 15 satellite collared caribou wintered in the southern foothills of the Brooks Range between the East Fork Chandalar and North Fork Chandalar River, Alaska. The other 2 satellite collared caribou wintered in the Ogilvie Basin, Upper Miner and Upper Whitestone River drainages in central Yukon.
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The annual calving survey was conducted using an ADF&G chartered Piper Super Cub on 1, 2, and 3 June 2009.
Seventy-eight radiocollared cows ages 2 years and older were observed during flights on 1-3 June, with all but one located in Ivvavik National Park. Extent of calving occurred from the Babbage River, Yukon to the Alaska-Yukon Border. Calving was concentrated in the hills west of the Tulugag River at the headwaters of the Spring River at elevations that ranged from 350-1200 meters (1,200 - 4,000 feet). It appeared that few caribou calved on the coastal plain.
Parturition rate (percent of cows that were pregnant or had given birth) was 78% for cows 4 years of age or older (n = 64) and is slightly below average.. Fifty percent of parturient cows (n=40) were observed with calves by 2 June suggesting peak of calving occurred on or before that date, earlier than normal. Thus, the peak of calving was probably on the 29 or 30 May, which is slightly earlier than normal. |
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Post-calving flights were conducted on 22, 23, and 24 June to estimate calf survival and the proportion of cows accompanied by calves (Figure 2). At this time, 71 radiocollared cows were observed including 63 of 78 cows observed in early June. Strong wind turbulence in the mountains prevented late June observations of 15 cows that were observed with calves (n = 9) or were judged to be pregnant (n = 3) or barren (n = 3) in early June. Post calving survival, estimated from cows observed with calves in early June whose dams were observed in late June was 75% which is well below average. The late June calf : cow ratio was 44 % which is the lowest on record for this herd. |
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From the 22 to 24 June, most of the herd was distributed along the northern foothills of the Brooks Range between the Kongukut and Jago Rivers, Alaska (Figure 2). Radiocollared cows were among loosely aggregated groups and generally segregated from bulls. Two of thirteen satellite collared cows were located in the upper Firth River drainage. Eight of 17 radiocollared bulls were also located, 4 in the upper Aichilik, 3 in the upper upper Okerokovik, and 1 in the upper Ekaluakat drainages (not depicted in Figure 2).
During 28 - 29 June, movement and aggregation of satellite collared caribou and favorable forecasted weather conditions indicated that adequate photocensus conditions might develop. On 30 June - 2 July, the PCH was radiotracked to determine the feasibility of a photocensus. Eighty-nine of 95 radiocollared cows and all 14 radiocollared bulls were located. On 30 June, 75 % of radiocollared caribou were located in 14 groups along the northern foothills of the Brooks Range. Most groups were aggregated sufficiently for a photocensus. However, the remaining radiocollar were among large groups of migrating caribou in the upper Jago and upper Aichilik Rivers. Unforecasted snow and rain at high elevations in the Brooks Range apparently resulted in a rapid movement of the PCH to the mountains beginning on the morning of 1 July. Over the following 24 hour period, at least 50% of the PCH had dispersed from aggregated groups, most migrating south near the Continental Divide.
Below is a summary of all caribou and information on whether or not they calved the past 11 years.  If you have any questions, please contact:
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