Porcupine Caribou were somewhat late leaving their summer range during the fall of 2006. There had been little sign of southern movement until after the rut. The rutting season tends to occur during the first 2 weeks of October, generally peaking about October 10th.
Satellite locations from October 14th and a radio telemetry flight October 16th showed that the majority of the herd was still north of Old Crow.
During the last 2 weeks of October, the caribou began their fall migration. The majority moved southeast and on Wednesday October 25th, showed up on the Dempster Highway between Sheep Creek and the Yukon / NWT border in huge numbers. One satellite collared caribou moved west into Alaska.
Within a few weeks, the migration began to slow. Very few Porcupine Caribou migrated south of the Ogilvie / Peel Rivers. It's interesting to note that last winter (2005 / 2006) the majority of the Porcupine Caribou wintered further south than they have been recorded in the last 20 years. This winter they remained further north than we've seen in the past 10 years.
Movements of Satellite collared cow caribou during winter months, December 1, 2005 to March 31, 2006
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From about the middle of November 2006 until late March 2007, the caribou tended to drift slightly north. The caribou concentrated in the Whitefish Lakes area near the confluence of the Porcupine, Bell and Eagle Rivers, and in the Richardson Mountains straddling the border between the Yukon and the NWT. A small concentration of caribou wintered east of Arctic Village in Alaska.
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Late Winter Telemetry relocations
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Locations of radio and satellite collared caribou, March 12 to 17, 2007
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As in past years, Tara Wertz and Dave Sowards with the U.S. Fish and Wildlife Service (Arctic National Wildlife Refuge) conducted the telemetry flight to relocate radio and satellite collared caribou. Despite some logistical problems and poor weather, they were able to fly the Yukon portion of the winter range between the 12th and 15th of March. On April 2nd, Tara and Don Carlson flew the Alaskan portion of the range.
Typically when flying a telemetry flight, the plane maintains an altitude of about 5 - 6000 feet above ground level. The caribou themselves are not seen, but the collars are "heard" as beeps. On the frequency list were 98 radio or satellite collars that had last been heard as "Active", or in other words, alive during the last telemetry flight in October 2006. Of these, 72 were heard in Yukon and 7 in Alaska. 7 new morts were heard, that is, caribou that had died since the last telemetry flight. 12 radio collars could not be located.
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Capture locations
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Locations of caribou captured March 13 to 21 for deployment of radio and satellite collars
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The goal this March was to replace radio and satellite collars that were due to go off the air or were starting to malfunction, and to add more radio collars to adult cows, calves and bulls in preparation for a census July 2007.
Radio collars were provided by the Government of the Northwest Territories, Canadian Wildlife Service and Ivvavik National Park. Satellite collars were provided by the U.S. Fish and Wildlife Service, the Alaska Department of Fish and Game, and Yukon Government
Captures occurred between March 15 and 20. Yukon Parks Ranger Dorian Amos and Tr'ondek Hwech'in First Nation Wildlife Steward Ryan Peterson assisted Martin Kienzler with these efforts, piloted by Karl Scholz of Fireweed Helicopters.
24 radio collars and 6 satellite collars were deployed.
Each spring since 2003, 10 of the past years female calves (known as short yearlings, as they are just short of one year old) have been collared to gather information on the survival of yearling caribou to 3 years of age. "BO4", caught as a calf in 2003 was recaptured this March and fitted with a satellite collar.
As has been tradition since 2000, the previous years' Johnny Charlie Scholarship recipient and wildlife technician trainee, a position funded by the Porcupine Caribou Management Board has been given the chance to come up with a name for a new satellite collared caribou. Simon "Spruce" Gerberding, who worked with Dawson biologists during the summer of 2006 will be re-naming "BO4."
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"BO4" as a short-yearling
"BO4" as a 4 year old
This year we had to change out a number of collars as well as add a few new caribou to the satellite program. Cocoa, Daphey and Pingo received new collars. Cocoa's collar was 3 years old, and time to be changed. Daphey and Pingo's collars were only 2 years old but were showing signs that they might become unreliable. We had been hoping to recapture and replace Iola's radio collar with another satellite collar, but could not relocate her during the telemetry flight.
This year we offered the pilots in Alaska and Yukon the chance to name a caribou. The Alaskan pilots (Dave Sowards and Don Carlson) decided that one caribou be named "Waldo", while Karl Scholz from the Yukon suggested "Belle", since that caribou was caught near the mouth of the Bell River.
Overall the caribou appeared to be in quite good condition.
Composition count data
During composition counts, caribou are classified as Cows, Calves, Mature bulls, and Immature bulls. Comp counts are useful in obtaining an estimate of overwinter survival of calves. To obtain an accurate representation of survival for a herd, it is necessary to classify caribou in as many wintering areas as possible as there can be differences between ranges.
Funding for the March 2007 composition count came from the Gwich'in Renewable Resources Board and Government of Yukon.
Data showed that there were some areas with much higher calf survival than others. In the Richardson Mountains calf survival was considerably higher than in the lower-lying areas. Overall, overwinter calf survival was slightly above the 20 year average, with 38.9 calves per 100 cows.
Dempster Snow Stations
In 1991, YTG set up 8 stations along the Yukon portion of the Dempster Highway in Porcupine Caribou range to monitor late winter snow accumulation and density over the long term. These stations were established in treed and open tundra terrain. The Dempster Highway passes through 3 of these regions (Richardson, Eagle and Ogilvie). There are 4 stations in the Ogilvie region, and 2 each in the Eagle and Richardson regions.
The 6 stations established on the Yukon North Slope were set up in 1999 to monitor snow depth as part of a muskox study. These stations have been measured by staff from YTG, Ivvavik National Park and Herschel Island Territorial Park. Since the muskox project ended in 2005, future measurements will be done opportunistically.
7 of the snow stations were measured on March 21st. 1 site in the Richardsons could not be measured for snow depth or density as it was too windswept. Snow depths were below average in all 3 regions. Densities were average to slightly below average in the Ogilvie and Eagle Plains regions, respectively. No ice layers were noted at any stations.
Download the Dempster Snow Report as a printer friendly Acrobat pdf file (130 KB)
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