The state's most important rivers are the Missouri, rising in southwest Montana and flowing north and then east across the state, and the Yellowstone, which crosses southeastern Montana to join the Missouri in North Dakota near the Montana border.
Habitats. Hoverflies can be found in every biotope but not in deserts. Each species tends to prefer a certain type of habitat and is limited to a distinct range within the country. There are relatively few species with broad habitat tolerances that enable them to be distributed throughout southern Africa.
A variety of birds nest in the mosaic of habitats provided by the tundra. Red Phalarope, Northern Phalarope, Pectoral Sandpiper, Semipalmated Sandpiper, Buff-breasted Sandpiper, Dunlin, Lapland Longspur, and Savannah Sparrow are small species that nest in the area. few species are present year-round. Rock and Willow Ptarmigan are the most abundant birds during winter and are found in patches of willows where they feed mainly on the buds. Ravens are the most conspicuous winter birds. A few Gyrfalcons and Snowy Owls may also be present, depending on the abundance of prey.