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Porcupine caribou herd at record number
Kristen Nelson Petroleum News
A photo census done in July of the Porcupine caribou herd shows an estimated 218,000 animals, which the Alaska Department of Fish and Game’s Division of Wildlife Conservation called a record high since population monitoring of the herd began in the 1970s.
A 2017 summary, published by the division last summer, describes the Porcupine herd as one of North America’s largest migratory caribou herds, and said that in addition to being a large herd, it has “the longest land migration of any animal in the world.”
The herd spends time in both Alaska and Canada, and during the winter typically forages from the Brooks Range in Alaska to the Richardson Mountains in Canada, with cows migrating hundreds of miles to the Arctic coastal plain for calving every spring.
Prior to this summer’s census showing an estimated 218,000 animals, the herd reached some 197,000 in 2013 when the last photo census was completed; there was a peak of some 178,000 animals in the late 1980s. The first photo census in 1977 identified some 100,000 animals.
The division said caribou populations are known for dramatic population changes and said once a herd becomes too large for its habitat, “the caribou become nutritionally stressed and the herd will decline.”
New technology The division said accuracy of the 2017 photo census was improved with a newly acquired digital photography system. Previously the division used a photo census technique which has been the same since World War II - with black and white photos, which were then printed and lined up to show the entire herd, and each caribou counted.
In the fall of 2016, however, there was an upgrade to a digital system linked to GPS and compatible with what the division called innovative software, allowing photos to be taken in a wide range of light conditions; photos with a larger footprint so fewer photos and less time are needed to photograph the caribou; digital imagery that allows automated alignment of multiple photos, eliminating overlap; and images in color and in high resolution, making it easier to pick out individual caribou so population estimates are more accurate.
Harvesting The division said harvest of the herd is thought to be between 1 and 2 percent annually. Canada’s harvest management plan requires an accurate harvest report from all hunters each year, the division said, and in 2013-14, about 2,920 Porcupine caribou were harvested in Canada, with more than 95 percent of the harvest by Gwich’in or Inuvialuit hunters.
Harvest in Alaska is primarily by local hunters in Arctic Village, Venetie and Kaktovik, the division said, with harvests estimated at 200 to 500 animals a year, but the division said that in Alaska, “harvest reporting is usually low.” Reported nonlocal Alaska resident hunters usually harvest fewer than 175 caribou, the division said.
Calving areas The division said that in the 1980s and 1990s most of the Porcupine herd calved south of Kaktovik in the 1002 area of the Arctic National Wildlife Refuge.
From 2004 through 2011, however, large portions of the herd calved along the Canadian border in Ivvavik National Park in Canada.
From 2012-13, the division said, GPS data showed that most of the radio collared cows calved on the coastal plain or adjacent foothills between the Babbage River in Canada and the Kongakut River in Alaska.
While portions of the herd still calved in Canada in 2014-15, the majority moved back to Alaska and calved on the coastal plain between the Hulahula and Kongakut rivers.
In 2016 most calving occurred on the coastal plain between the Alaska-Canada border and the Sadlerochit River and in 2017 the herd calved on the coastal plain from the Sadlerochit Mountains in Alaska to the Babbage River in Canada.
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