Strategic Acquisition and Management of Small Parcels of Private Lands in Key Areas to Address Habitat Fragmentation at the Scale of the Yellowstone to Yukon Region

Large landscape conservation designed to ensure the survival of all native species on an increasingly human-dominated planet requires us to think at multiple scales and across multiple jurisdictions (Locke 2012). In the Yellowstone to Yukon region in the northern Rocky Mountains of western North America, the full complement of native species is found across the landscape but is not always evenly distributed. Grizzly bears (Ursus arctos) have been identified as a surrogate for the conservation of many other species because they are wide-ranging habitat generalists and are very vulnerable to some human disturbances, including housing developments (Frankel and Soulé 1981, Craighead et al. 1995, Meffe and Carroll 1997, Schwartz 2010). Where they occur, managing the land for their persistence is a very useful planning tool for maintaining and restoring wildlife connectivity across a vast landscape.

The Cabinet-Purcell Mountain Corridor is part of one of the largest connectivity restoration and maintenance initiatives in the world, the Yellowstone to Yukon (Y2Y) Conservation Initiative. Launched as a concept in 1993, a community of conservationists and conservation biologists agreed that this vast region of the Rocky Mountains should be considered as a whole. Subsequently, Y2Y participants struggled to determine what that would mean in an applied sense. Initial steps included both the compilation of an atlas identifying the region's shared geology, ecology, and human history (Harvey 1998), as well as attracting philanthropic attention (Tabor 1996). The atlas included range distribution maps of various species, including grizzly bears, and a model of habitat fragmentation. This fragmentation model (Figure 1) combined with grizzly bear current range maps revealed that the bears were concentrated in intact landscapes (with exception of Central Idaho where they are absent). Notably, the model revealed a zone of heavy fragmentation just north of the Canada-U.S. border along Highway 3, which bisects the entire Y2Y region. It also revealed fragmentation in the Cabinet-Yaak area of extreme northwest Montana where grizzly bears still persist in small, increasingly isolated populations. The model showed also that Central Idaho consists of a large area of intact wilderness. However, grizzly bears have been extirpated from that area which had become isolated from habitats still supporting bear populations in Yellowstone National Park and along the Canada-U.S. border. This problem was already well known, and Central Idaho's wilderness had already been identified by conservationists and grizzly bear experts as being capable of supporting a grizzly bear population (Boyce and Waller 2003).

The idea of focusing on grizzly bears was not new. The species had already been studied extensively in some parts of the Y2Y region. Indeed awareness that the many isolated grizzly populations that existed in 1922, with the exception of one centered on Yellowstone National Park, had been extirpated by 1975 was a major factor in the evolution of the Y2Y idea (Locke 1994, Mattson and Merrill 2002).

In parallel, continuous field research by the Trans-border Grizzly Bear Project (transbordergrizzlybearproject.ca) using radio-collaring and DNA hair snagging along British Columbia's Highway 3 determined where existing grizzly bear movements were occurring. These movements were mapped spatially and overlaid with land ownership data, revealing that male bears moved across Highway 3 in the Kidd Creek area (among other linkage areas) east of Creston, B.C., south to the Yaak area of northern Montana. Another connection lay east-west from the Purcell Mountains to the Selkirk Mountains across the Purcell Trench in the area of Duck Lake north of Creston. Many years of study for grizzly bear recovery led by the U.S. Fish and Wildlife Service demonstrated that the Yaak population was isolated from the small Cabinet Mountain population immediately to the south of it (Proctor et al. 2012). That population was in turn bounded on the south by the Clark Fork River. Informed by these findings we were able to develop a broad strategy set for linkage at the landscape scale (Figure 2).

We set as our first task the...