River near Nashua, Montana. Throughout the region lie a multitude of Cretaceous-era dinosaur fossils, as well as many archaeological sites, a legacy of the Blackfoot indigenous people who hunted, gathered, and camped in the area prior to European contact. Findings of projectile points indicate the area has likely been sporadically inhabited since the end of the last glaciation. Ecology The Milk River Natural Area is part of the Grasslands Natural Region, one of six natural regions in Alberta. Within the Grasslands Region, it is part of the Dry Mixedgrass Natural Subregion, characterized by the most arid conditions in Alberta, with hot summers, cold winters with little snow cover, and high evaporation leaving a large moisture deficit in the growing season. Annual precipitation averages less than 300mm (12 inches). Soils of the area are primarily solonetzic and brown chernozemic. At the next sub-level, it is part of the Northwestern Glaciated Plains Ecoregion, the predominant ecoregion throughout the Milk River watershed. With its diverse landscape of grasslands, shrubs, badlands, wetlands, and riparian woodlands, the Milk River Natural Area supports a large number of rare, threatened, and endangered species in a relatively small amount of space. Overall, 80% of Alberta's species at risk are concentrated in the Milk River Watershed area as a whole. Fire is a significant ecological process, with the last large wildfire having occurred in August 2007. It was caused by a lightning strike in Montana and crossed the international border, but was quickly suppressed after burning 125 hectares of the natural area and 38 hectares in neighboring Kennedy Coulee Ecological Reserve. As a relatively large and undisturbed representation of natural mixedgrass containing rare or unique landforms, habitat for focal species, and intact riparian areas, it has been identified as an Environmentally Significant Area (ESA) with national significance. Flora The diverse terrain and soils of the Milk River Natural Area lend themselves to a large variety of plant communities. In the protected area, aside from non-vegetated badlands, the primary vegetation cover is dry mixed grassland, with the dominant species being needle-and-thread (Hesperostipa comate) and blue grama grass (Bouteloua gracilis). Other grassland species associated with the area include northern wheat grass (Agropyron dasystachyum), western wheat grass (Pascopyrum smithii), prairie june grass (Koeleria macrantha), sandberg bluegrass (Poa sandbergii) and various sedge species. The flood plains surrounding the river contain large stands of plains cottonwood (Populus deltoides) and sagebrush flats. Moss phlox (Phlox