The mixed-grass prairie of northern Valley County (known locally as the ?North Valley Grasslands?) is one of the largest blocks of intact grasslands in Montana and has been described by botanists as ?possibly the best intact site of a rare midgrass (northern porcupine grass-thickspike wheatgrass) prairie remaining in the United States.? This site supports 15 grassland species of State conservation concern, five of which also are globally threatened. Consequently, the site is an outstanding example of an IBA of Global significance.
During the breeding seasons of 2001 through 2005, biologists from the Montana Natural Heritage Program and the Bureau of Land Management visited 332 point-count transects (three points per transect) to survey grassland birds. Seventy-three species of birds were detected, including seven that are endemic breeders in the Northern Great Plains: Ferruginous Hawk, Long-billed Curlew, Sprague?s Pipit, Lark Bunting, Baird?s Sparrow, McCown?s Longspur, and Chestnut-collared Longspur. Numbers of Long-billed Curlews, Sprague?s Pipits, and Chestnut-collared Longspurs exceed thresholds for an IBA of Global significance, as do those of McCown's Longspurs and Baird?s Sparrows for Continental significance. Horned Larks and Western Meadowlarks, though not of high conservation priority, also are especially abundant.
The point counts surveyed about 13% of the grassland habitat within this vast IBA. Thus, one could conservatively estimate that the number of pairs of grassland passerines breeding in the IBA is 4-5 times higher than the number of birds detected on the transects.
The Northern Great Plains has lost most of its native prairie, and large intact blocks of grassland like those in North Valley County are very rare. This site has been proposed for a large wind farm, which would result in a direct loss of native prairie as well as habitat degradation associated with roads and powerlines that would be constructed to support the wind farm. Some of the grassland habitat also is at risk to conversion to agriculture.