The Intermountain Ecological Region (Intermountain) of British Columbia (Region 8) includes the Canadian portion of the NABCI Great Basin and the majority of the Canadian portion of the Northern Rockies Bird Conservation Regions. It occupies approximately the southern half of the province. The region is delineated by the crest of the Coast Mountains on the west, the crest of the Rocky Mountains on the east, the southern extent of the boreal forest to the north, and the boundary with the United States on the south. The region covers 320,000 km2, over 34% of the area of BC, and supports a breeding waterfowl population of approximately 1.1 million birds. Four percent of this area (12,300 km2) is lakes and wetlands. The Intermountain contains 4 ecoprovinces, including 10 ecoregions and 37 ecosections. Elevation ranges from 200 meters to over 3,000 meters above sea level. Within the Intermountain, the habitats most important to waterfowl occur in the valleys and on mid-elevation plateaus.
Ninety-two percent of BC is publicly owned provincial Crown land with the remainder privately owned, First Nations reserves, or parks. The majority of wetland drainage has taken place on private land in valley bottoms where up to 80% of wetlands have been drained. While the few wetlands remaining on private land are highly productive, by far the majority of remaining waterfowl habitat exists on Crown land. Crown land is available to the public and its regulation is defined by public policy and legislation.
Importance to waterfowl
The Intermountain contains important breeding habitat for 26 species of ducks as well as Canada geese. Two conservative provincial estimates of breeding waterfowl populations suggest about 1.7 million ducks breed in BC or approximately 4% of the breeding waterfowl population in Canada. It is particularly important to Barrow’s goldeneyes and provides breeding habitat for more than 60% of the world’s population of this species. A recent effort to calculate the number of waterfowl breeding in the interior alone suggests 1.1 million ducks or 65% of the total provincial waterfowl population breed in the Intermountain. Density of breeding waterfowl in the Intermountain ranges as high as 36.3 pairs/km2 (94 pairs/mi2) in some locations.
Population data from 1967-69 and 1987-98 suggest that mallards, northern pintails, blue-winged teal, common goldeneyes, ruddy ducks, harlequin ducks, common mergansers, and red-breasted mergansers have markedly declined in abundance in BC during the last 30 years. More recent trend estimates also suggest that Barrow’s goldeneyes and lesser scaup are declining throughout the Intermountain. Although it is unclear what factors may have contributed to these declines, it is likely that wetland loss and rangeland degradation have been key factors contributing to the decline of dabbling ducks. Intensified logging activities, and its accompanying negative effects on wetland and riverine habitats, have likely contributed to declines in several species of diving ducks.
In addition to providing important breeding habitat for waterfowl, the Intermountain is used extensively by migrating and wintering waterfowl. The strategic location of the Intermountain between significant breeding areas in Alaska and key wintering areas in California and western Mexico contribute to heavy use of this region by migrating waterfowl. Up to 8 million waterfowl comprised of 38 different species migrate through the interior of BC. Also, growing numbers of waterfowl winter on the rivers and large lakes in the Intermountain. Notably, more than 2,000 of the world’s remaining 19,000 trumpeter swans currently winter in the Intermountain.