<p>LAMAR VALLEY, YELLOWSTONE NATIONAL PARK -- It's a morning of freezing rain in the valley and a pack of wolves is roaming around Black Tail Creek. A few pups gnaw on an old elk carcass while some adults scout the nearby valleys for prey. Not far away, a few elk have sensed the impending danger and are dashing about. To the tourists in the park, the prospect of a wolf attacking an elk is riveting. To the biologists staring into their binoculars, the real action is taking place in Black Tail Creek itself.</p>