Wild Hunters 6: Winter Caribou Hunt
Last week in Denali I was treated to a scene that could have been straight out of the Ice Age, as wolves and caribou once again did their age-old dance during a hunt on the wintering grounds. Sometimes the wolves end up with a meal, sometimes the caribou prevail.  But always it is a fascinating thing of beauty to watch.  
Denali caribou have now moved northeastward to a traditional wintering area in flatter, more open terrain along the northern and northeastern park boundaries.  They are foraging primarily on lichens, mostly in scattered small groups.  This represents an annual windfall for resident wolves such as the Stampede family.  The wolves move almost constantly throughout the area, searching for and testing caribou until finding the next fresh meal or frozen winter kill.  Currently the Stampede family consists of four adults and the four (now adult-sized) surviving pups from the litter they produced in May 2008; see what these pups looked like at 5-6 weeks old, in the photo at the top of the June 24, 2008 blog entry.    
As we approached in the research airplane, the eight Stampede wolves were moving at a steady pace across the open terrain toward a group of 10 caribou, including 2-3 calves, foraging just out of view in a creek bottom, several miles (4-5 km) away.  The wolves seemed to know exactly where the caribou were, but the caribou were oblivious to the oncoming wolves. The photos below and at the top of the page show what happened over the next 5-10 minutes.
Below (3 photos):  The eight wolves approach to within a couple hundred yards (meters) of the caribou in plain view, but the caribou do not see them initially as they continue grazing on lichens.
Below, the fourth caribou from the left sees the nearby wolves while the other caribou continue grazing.
As we circle to the left behind the 10 caribou, they bolt from the wolves, first by running a short distance to the left and then up onto the open tundra, where there is less brush and better footing.
Below: The caribou initially pull away from the wolves because the wolves must change direction (turning left from their original route) and run through a low brushy area.  By fleeing in a tight band, the caribou make it more difficult for the wolves to focus on any single vulnerable individual, such as a calf.  
Below (2 photos): Five wolves can be seen in pursuit (3 pups are just behind).  In the first photo, the alpha male is just emerging from the ravine, near the top center, while two other wolves are already on the tundra running straight toward the caribou.  In the second photo, the alpha male is running faster than the others; note how much further he has run from the top of the ravine relative to the additional distance the others have covered.  More importantly, while the two wolves to his right are still running directly toward the caribou, he is running toward a point ahead of the caribou, apparently anticipating that they will turn to their left.  
Below and top of the page:  The alpha male anticipated correctly!  The caribou turn to the left, along the flight path he was projecting.  Perhaps they are doing this because they are hoping other groups of caribou in that direction will divert the wolves’ attention.      
Below:  One of the other groups of caribou can be seen in the background.  They are watching this chase intently.  Within the next few seconds, as the chase begins turning more in their direction, they, too, begin fleeing.  Already the lower caribou are pulling away from the wolves.
Below:  The wolves continue to pursue, but the gap is widening.
Below (2 photos):  The eight wolves give up after another couple of minutes, as the caribou continue running and we circle from the front to the rear of the scene.  No meal from this chase, but there will be other opportunities, probably before the day ends ...    
Jan 30, 2009
Four wolves of the Stampede family in hot pursuit of 10 caribou in Denali National Park, January 2009; four other wolves are lagging just outside the photo.  Will this chase produce a meal for the wolves?  See below.