By Erling Friis-Baastad
It appears that no news day is complete without some mention of drastic changes in the circumpolar world. The summer ice pack is retreating further north. Warmer weather is causing major changes in the makeup of plant and animal populations. Ecosystem changes are presenting new challenges, while opportunities for resource extraction and transportation are opening up as melting ice leaves seascapes and waterways exposed.
Northerners face an uncertain future, at once threatening and promising. Realizing this, eight countries with land and sea floor in the Arctic, plus a number of indigenous groups, formed the Arctic Council in 1996. As Yukon zoologist and Arctic researcher Don Reid of the Wildlife Conservation Society says, one of the goals of the council is “to avoid a free-for-all: everybody going up there and doing whatever they will.”
At the political level, those members and other participants realized that they needed technical scientific information on a great many topics in order to create effective policies and co-operatively manage activity in the North, says Reid. They established a variety of technical bodies that report to the Arctic Council, one of which is called Conservation of Arctic Flora and Fauna: CAFF.
“The politicians wanted to know, ‘What is the current status of Arctic biodiversity and what is affecting it mostly?’” says Reid. CAFF’s response was to launch a number of initiatives, including the Arctic Biodiversity Assessment. This whopping document comes in at over 1,000 pages and is not yet quite complete, says Reid. Its myriad chapters include data on taxonomic groups - birds, insects, amphibians, fishes and so forth - as well as on such topics as invasive species, genetics and ecosystems. A little more than two years ago, Reid was invited to help lead the chapter on Arctic mammals, which included the input of contributing authors from around the world.
First, the researchers had to settle on parameters of time and space. How far back would they - or could they - go to answer questions about distribution and abundance? “We’re being fairly broad with that because we brought quite a bit of traditional ecological knowledge into the writing of the report,” Reid says.
“Scientific knowledge goes back about 50 years. Rarely do we have data going back more than that. It’s not a very long time period and that, of course, presents problems in documenting real changes. Nevertheless, there have been substantial ones happening.”
Researchers had to settle on what they would include in the Arctic. The tree line formed a boundary, at least on land. The oceans were a bit more difficult to define. The Bering Sea was included, as was the Sea of Okhotsk. The demarcation included Iceland at its southern boundary, northern Siberia and much of northern Eurasia. “In the Yukon our definition of treeline was the crest of the Brooks Range, into the British Mountains and down the Richardson Mountains. Everything flowing out to the Arctic Ocean down the north side of the continental slope would be included in the Arctic.”
Finally, what constitutes a true Arctic mammal? Reid and his colleagues did a broad sweep of any mammals ever documented to occur in the Arctic. Some only showed up there by accident, or at most very rarely. Many more appeared both in the Arctic and south into the boreal. “Relatively few mammals, being warm-blooded, have actually managed to call the Arctic home exclusively,” he says. These include the Arctic fox, Arctic hare and Peary caribou, most notably.
Other northern mammals such as Arctic ground squirrels, gray wolves (which are often white in the Arctic), brown lemmings, tundra voles and wolverines, inhabit the boreal forest regions as well as the Arctic.
Before looking at today’s populations and distribution of Arctic animals, it’s informative to look back to the Pleistocene, and its refugia, - large unglaciated regions where animals could find food - in order to catch a glimpse of where they came from. “The refugia of the last glaciation, the last ice age, have been hugely influential in the present distribution of where Arctic mammals are around the globe,” says Reid.
The Beringian refugia was especially vast and had a huge influence on present populations. “It extended not only into what we know as northwest Yukon and through Alaska, but even across much of northern Siberia and into the Ural Mountains,” he says. “If you look at the distribution of Arctic mammals right now, that is the geography where the greatest diversity is by far.”
Significantly, thanks in large part to wide stretches of water, like Hudson Bay and Dease Strait, many mammals haven’t been able to move far across the Arctic from the refugia in which they spent the ice age. “When you look at birds and insects and fishes, this pattern all breaks down. They are much more mobile and much more able to deal with water.”
But, says Reid, the ultimate focus of the mammal chapter is on more recent history, on what’s happening now. Surprisingly “few things have changed in terms of distribution and abundance that can be directly attributed to climate change,” at least as far as the Arctic itself is concerned. Most well-documented changes were brought about by human activity, especially harvest and translocation of animals. The destruction of whale populations by a rapacious international fleet of hunters is well known. Less often considered are the initiatives by which fur bearers like mink or meat animals like muskoxen were transplanted for economic reasons.
“When it comes to climate change,” says Reid, “the place where there are definite patterns of change happening with mammals is right in the interface of the northern boreal forest with the low Arctic tundra, and ocean areas losing their summer ice for the first time.”
Those changes will be the subject of the next Your Yukon.
This column is co-ordinated by the Yukon Research Centre at Yukon College with major financial support from Environment Yukon and Yukon College. The articles are archived at http://www.yukoncollege.yk.ca/research/publications/newsletters_articles