Connectivity

Connectivity is inextricably linked to the problems of reduction in viable habitat. The term "connectivity" describes the potential for areas of grizzly bear habitat, and indeed, ecosystems, to link, permitting the passage of wildlife between them. Connectivity is of paramount importance in consideration of new understanding that many "reserves", such as national, state and provincial parks, are too small to function as stand-alone habitats for large mammals. This is particularly true of predatory mammals such as bears and wolves, both of which may range over several thousand square miles. In order to compensate for this inadequacy in protected areas, linking them to one another through protected "corridors" strikes some balance in making it easier, or possible, for animals to move between them. Connectivity facilitates the breadth of movement essential to meet range requirements and maintain genetic diversity in populations of wildlife.

Roads and towns and many other features of human development tend to "cut" viable bear habitat up, reinforcing the impression of isolated areas that, inevitably, are too small to fulfill their intended purpose. Certain roads can be very difficult for wildlife to cross, and the problem they present is compounded by the potential for mortalities due to traffic. In the Bow Valley, in Alberta, Canada, for example, Banff National Park is literally bisected by the Trans-Canada Highway, which also bisects the whole Rocky Mountain ecosystem. The Trans-Canada is a four-lane road which is fenced to reduce the potential for wildlife to be hit by vehicles. This precaution, however, is also very effective in preventing wildlife from moving freely across the park, with the net result that species on each side of the Bow Valley are developing separately from one another, implying a significantly reduced gene pool. The Bow Valley is also divided by a smaller road, the Bow River and the Canadian Pacific Railway.

In extending the example of the Bow Valley, which is one of many areas similarly affected by development, Canada Highway 3 also bisects the Rockies 300 kilometres to the south. South of that, in Montana, the Burlington Northern/Santa Fe Railway does the same, as again US Interstates 80 and 90 do to the south of it. Towns like Banff, Alberta, and Missoula, Montana, which have both grown significantly in recent years, sit like plugs along these linear disturbances, blocking valleys that used to be wildlife migration routes, further fragmenting habitat. The pattern of recession of grizzly bear habitat from including all of the west of the US and Canada at the beginning of the last century, to their range today, has been manifest through a process of development, marginalisation, fragmentation and finally impoverishment that leads to redundancy. With the islands of intact habitat that remain, and with the preserves that are scattered within them, it is essential that as much connectivity be restored as possible. Without it, such islands will be inadequate as habitat for grizzly bears and the recession of the last 80 years will continue.