Lamar Valley, Yellowstone National Park, Wyoming — Out of darkness the Lamar Valley comes to life. Streaking clouds overhead reflect the first signs of the approaching day — true big sky country captured within the broad picture of HD. Slumbering bull bison awaken and join the grazing herd, eating their way towards the head of the valley. Bison feed mainly on grasses and can cover 3km in a day of grazing. They once traveled in herds of thousands, but now, a typical bison herd is about 50 animals. Calves scamper through the tall grasses to catch up with the pace of their hungry elders. Calves weigh 30-70 pounds at birth and can travel with their mothers within 3 hours. Swallows dart through the line of trees along a cold stream flowing off of the neighboring Wyoming peaks.