Wildlife photography of an American Bison cow resting her head on a Nurse Rock near a Douglas Fir in Yellowstone National Park

In the heat of Summer, a well-fed American Bison cow relaxes in the shade of a Douglas Fir amid Nurse Rocks in Yellowstone National Park. There is an area in the Lamar Valley where most of Douglas Firs grow against very large boulders. Called “erratics” these granite boulders were carried many miles before being left behind by glaciers. Locals fondly call them “Nurse Rocks” for the care and shelter they provide growing trees by creating a micro-climate that protects seeds, retains water, and promotes grass and root growth.