Porcupine Caribou Update:
Winter 2011 - 2012 to Fall 2012

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       Fall Movements 2011
       Winter 2011-12 Satellite Collar Locations
       Late Winter 2012 Telemetry Relocations
       March 2012 Captures
       Snow Conditions in the PCH Range, 2012
       Calving update, 2012
       Photo Census 2012
       Late Summer and Fall 2012

Fall Movements 2011

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Movements of Satellite collared cow caribou during late summer and fall, 2011.

Thoughtout late summer of 2011 the Porcupine Caribou Herd was spread out over their summer range. Caribou were available to hunters near the Yukon / NWT border along the Dempster Highway and extended across the northern Yukon and Alaska, mostly north of the Old Crow Flats as far west as Arctic Village. By late September 2011 the majority of the caribou that were in the Yukon had moved west into Alaska. Telemetry flights by US Fish and Wildlife Service Biologists middle October through early November indicated that as many as 75 % of the herd was in Alaska. One satellite collar that had moved into Alaska in late September moved back into the Yukon in mid October, however her collar unexpectedly stopped transmitting on November 11th in Fishing Branch, so we were unable to observe where her group ended up for the winter. One radio collared bull was located in the Yukon along the Tatonduk River in the south west corner of the herd range, and there were small groups of Porcupine Caribou along the Dempster Highway and other parts of their Yukon range that appeared not to be associated with radio or satellite collars.

Winter Satellite Collar Locations 2011 - 2012

Movements of Satellite collared cow caribou during winter months, December 1, 2011 to March 31, 2012
Throughout the winter of 2011 - 2012, Porcupine Caribou remained in the area around Arctic Village overlapped with caribou from the Central Arctic Herd. A few scattered groups of Porcupine Caribou wintered along the Dempster Highway north of Eagle Plains and along the Ogilvie River.

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Late Winter Telemetry Relocations March 2012

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Locations of radio and satellite collared Porcupine March 2012

Telemetry flights to locate radio collared Porcupine Caribou were conducted in March 2012 by Alaskan biologists flying in US Fish and Wildlife Service aircraft.

A total of 70 radio collars were found from a list of 98 potentially active collars. Of the radios heard, 4 were new mortality signals. Of the collared caribou that were found alive, 69 (99 %) were located in Alaska, while only 1 was located in the Yukon.

Caribou were spread out from Arctic Village along the lengths of the Chandalar, Sheenjek and Colleen Rivers. Central Arctic caribou were mixed with the Porcupine Herd through much of the Alaskan winter range, more than we typically see.

The 1 collar in the Yukon was west of Old Crow, and had likely moved into the Yukon in late winter.

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March Captures

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Capture locations March 2012

The goal for March 2012 was to recapture a number of cow caribou that had originally been collared with VHF transmitters as 9 month old calves (also called "Short-yearlings" as they are just short of being one year old), and replace their transmitters with Iridium GPS transmitters. The Iridium GPS collars are a new model of Satellite transmitter, and are a vast improvement over the older style Argos collar. Though size, weight and cost is virtually the same between the 2 types, the number and accuracy of locations is much better with the Iridium collars. The new Iridium collars have been programmed to transmit a location every 5 hours, every day for up to 3 years. With the Argos collars we are only able to obtain 1 location per week for most of the year, and every second day during the period of calving to have them last for 3 years.

Iridium GPS collars were provided by the U.S. Fish and Wildlife Service and the Canadian Wildlife Service. Additional VHF radio collars were provided by the Vuntut National Park for deployment on bull caribou in preparation for a possible Photo Census in 2012, and to collar an additional 10 short-yearling cows. Telemetry to relocate caribou for recaptures was conducted by USF&WS staff and Papa Zulu Aviation from Tok, Alaska. Captures were conducted by USF&WS and YTG staff using an R-44 helicopter (Quicksilver Aviation, Fairbanks, Alaska). All captures were conducted in Alaska.

A total of 23 caribou were captured by net-gun for recollaring or deploying new collars. This included 7 adult female recaptures, 10 new random female short-yearlings and 6 bulls. All adult cows were fitted with Iridium collars, while the short-yearlings and bulls received radio transmitters.

Following the capture events in March, we now have a total of 14 satellite and 90 VHF radio transmitters on Porcupine Caribou. All satellite transmitters are on cow caribou. Of the VHF transmitters 81 are on cows and 15 are on bulls.

Due to the high amount of mixing between Porcupine and Central Arctic Caribou on the winter range, a March composition count was not possible in 2012.

Snow Conditions in the PCH Range, 2012

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Yukon Snow Depths 2012

Snow Survey data obtained from Water Resources Branch of Yukon Government for along the Dempster and in Old Crow, and from Ivvavik National Parks staff along the North Slope indicated that snow depths on the Yukon portion of the PCH range were above average for late winter in 2012. Data on snow conditions in Alaskan PCH range were not available.

Calving Update 2012

Maps and data provided by Jason Caikoski, ADF&G

Download the memorandum by Jason Caikoski of the Alaska Department of Fish and Game
to read the entire 2012 PCH surveys memo as a printer friendly Acrobat pdf file (588 KB)

From mid April through end of May, 2012,the PCH migrated northeast from wintering areas in Alaska to the coastal plain in the Yukon. By late May the caribou had arrived on the calving grounds with 15 of 16 satellite and GPS collars along the Yukon coastal plain. The remaining collar was in the Jago River drainage in Alaska. Calving was concentrated on the coastal plain and in the foothills between the Firth and Blow Rivers in the Yukon, with a few animals in Alaska. A large number of Porcupine Caribou calved between the Babbage and Blow Rivers, an area outside of the recent calving range on the Yukon's coastal plain. In recent years that the PCH have calved in the Yukon, the areas of highest concentration have most often been between the Babbage and Firth River within Ivvavik National Park.

In late May USF&WS biologists conducted a range wide telemetry survey and located most VHF collars. They spent addional time obtaining good locations on old collars lying in the field for a collar recovery effort scheduled for later in the summer.

For the first time since 1987, poor weather prevented adequate radio tracking to estimate parturition rate and calving distribution. Extensive fog on the coastal plain and adjacent mountains prevented low level flights across most of the PCH calving grounds, and though locations of most collars were obtained, the sample size of collared cows actually observed was too low to determine calving success.

Radio tracking flights conducted during 20 - 21 June to estimate post calving survival of calves and the calf:cow ratio were also unsuccessful. Post-calving groups consisted of tens of thousands of densely packed caribou making observation of individuals impossible.

Photo Census 2012

Porcupine Caribou continued to be monitored through the end of June and into the first week of July to see if a census could be conducted. On July 5th reports came in of 1000's of caribou along the Dempster Highway near the Yukon / NWT border. A radio tracking flight confirmed that 4 bull collars and many 1000's of caribou in post-calving groups had moved onto the Dempster Highway, something that we are not aware of ever having occurred before.

High winds in the Richardson Mountains made it impossible to take photos adequate to estimate numbers. The majority of the PCH was further split into 2 distinct groups in Alaska with 42 % of radiocollars on the south side of the Brooks range, and 53 % of radiocollars on the North Slope.

Caribou aggregations were never sufficient to conduct a photocensus in 2012.

PCH Post-calving groups along the Dempster Highway, July 2012

Late Summer and Fall 2012

During summer months Porcupine Caribou made random movements across the summer range. By late August the caribou were concentrated through the north Richardson Mountains, along the north slope of the Yukon between the NWT border and the Babbage River, and along the eastern edge of the Old Crow Flats. In early September the caribou began to move across the Yukon and by mid September virtually all satellite collars had arrived in the vicinity of Arctic Village. Small groups of caribou were reported along the Dempster Highway and crossing the river near Old Crow. It seems as if the caribou are set to winter in Alaska again this year.

If you have any questions, please contact:
Mike Suitor or Martin Kienzler
Regional Management
Box 600
Dawson City, YT
Y0B 1G0
Phone (867) 993-6461
Fax (867) 993-6548
Email mike.suitor@gov.yk.ca or martin.kienzler@gov.yk.ca

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