 The Black Hills are a fascinating meeting ground, where east meets west and north meets south. Ecosystems, climatic zones, and even human cultures have sometimes collided here, often violently. For example, we call this a Black Hills spruce because it's found in the cool drainages of the northern hills, but really it's a white spruce, akin to those that grow in the conifer forests of Canada and Alaska. How did it get here? It's a glacial relict. During the ice ages, continental glaciers pushed into the northern plains, creating a climate similar to the northern Canada, and bringing that ecosystem south. When the ice retreated, isolated stands of these spruce trees, along with some other plants and animals of the far north, remained in the Black Hills. Birds and mammals typical of the eastern hardwood forests encounter species from the rocky mountains here in the Black Hills. For example, indigo buntings from the east sometimes interbreed with lazuli buntings from the west in this area. Likewise, the yellow-shafted race of the common flickers can hybridize here with the red-shafted race from the western U.S. The Black Hills, this meeting ground, this island in the plains, is a most diverse and fascinating region. Many people think that the Black Hills are exclusively in South Dakota, but about a fourth of them are here in Wyoming. I'm Gene Gade from the University of Wyoming Cooperative Extension Service.