This bear cub was enjoying a delicious elk calf carcass when a coyote appeared, looking for a snack. The two of them sparred for a while, with the coyote trying both frontal charges and sneak attacks from the rear. However, the cub successfully defended lunch.
We never saw mother bear.
Spotted northwest of Roosevelt in Yellowstone, May 2010. This area is the most reliable place for me to spot black bears in the park.