In his line of work, David Fraser has to use the word "peripheral" regularly, but it is far from the favourite word in his vocabulary. In fact, he lumps it right in there with terms such as "overmature forest" and "barren lake."

An endangered species specialist with the wildlife branch in British Columbia, Fraser regularly provides information and does research on peripheral species, the term used to describe populations of animals at the very edges of their range.

Until recently, British Columbia assigned peripheral species low ranks on the list of management priorities. Populations living off in the hinterlands were not listed as candidates for threatened or endangered status.That situation has changed, and many BC peripheral species are now listed as being "at risk," but Fraser still describes "peripheral" as a loaded word.

"If you look it up in the dictionary it has a whole pile of other connotations," he says, citing synonyms such as secondary, non-essential and borderline.

In the last few years, new research has shown that peripheral species have an important role to play when it comes to conserving species. In fact, some biologists now are saying that protecting peripheral species is critical if we really want to maintain biodiversity.

"New information is coming out about the role that peripheral populations play in evolution and the pattern of species collapse, with the common pattern being that they collapse at their edges," he says.

And not just at any old edge. In the northern hemisphere the most common pattern for mammals is to collapse to the northern and western edges of a species range.

"In Alberta, B.C. and the Yukon, that gives things a whole new twist because all of a sudden we will be keepers of species that traditionally have been widespread, but are in now in trouble in many places."

Fraser points to caribou and wolverines as two examples of animals that are not faring well across much of their orignial range.

In some cases peripheral populations are the only ones that are healthy enough to provide animals for reintroduction or re-colonization. Sea otters, California bighorn sheep and, closer to home, wood bison are all examples of species re-introduced from healthy populations that escaped over-harvesting or habitat loss at the northern edges of their range.

Also, peripheral populations might give some species a genetic edge, helping them to survive in a changing world. Some research shows that animals far removed from the core of their range are liable to do things in completely different ways than other members of the same species living near the core.

For example, the only prairie dogs known to hibernate, so far, live in northern Manitoba, at the very northern edge of this species range. Attempts have been made to get prairie dogs to hibernate in laboratories, but these experiments have never worked.

"The theory is that most evolutionary processes that allow species to adapt to new environments probably take place at the edge of a species range, so some people think that the edge-of-range changes help to maintain diversity," he says.

A species may be comprised of several populations across its range. Within a species, populations at the edges of their range are often genetically distinct. Many biologists consider the loss of genetically distinct populations to be as important as the loss of species.

Fraser cites many other reasons why peripheral species are important. Some species are at risk over large portions of their range, so peripheral populations can be just as important as ones closer to the core.

Areas that are attractive for humans to settle in often help create "hot spots" for peripheral species, and challenges for wildlife managers. In British Columbia, intensive development in places like the Okanagan Valley and the Gulf Islands can lead to habitat loss for peripheral species.

In the Yukon, peripheral species include two amphibians and a number of bird species in the southeast Yukon, as well as mammals such as white-tailed deer that are gradually moving further north.

Several of the songbirds in the southeast Yukon do not dwindle off in numbers, as one might expect of peripheral species, but occur in high densities.

"This means that these populations are probably not trivial, and should not be discounted by mangement," says Fraser. "They might actually be biologically quite significant."

So what should we call these often unique populations of animals and plants living off in the boonies, as far as the rest of their kind are concerned?

Fraser concedes that "populations at the edge of their range" does not roll off the tongue very easily. He thinks of them as species at the cutting edge, whose importance will most likely continue to grow as we learn more about them.

David Fraser is with the wildlife branch of the BC Ministry of Environment, Lands and Parks, and can be contacted at Dave.Fraser@gems8.gov.bc.ca.