I took this photo in Katmai National Park and Preserve, Alaska. A mother grizzly bear and her three cubs were running away from a big boar.

Male bears (boars) frequently kill cubs that are not their own. This infanticide is a common, brutal survival strategy where the male kills cubs to bring the mother back into estrus (heat), allowing him to mate with her. This behavior is seen in species like brown bears, grizzlies, and polar bears.

Grizzly bear mother