A Canadian study showed that red foxes and coyote territories did not overlap and that red foxes avoided raising pups where coyotes are active. Bears ignore the red fox since they cannot catch them. Wild cats including the mountain lion, lynx and bobcat will all kill a fox if they have opportunity to do so. Bobcats would likely not take on an adult. The lynx usually catches a fox when the snow is too deep for the fox.
Deep snow favours the large-footed cat.
Large birds of prey kill fox pups that are in the open. Eagles even occasionally swoop at adults. The fox either takes up a defensive position, rigid and tense, with its tail straight up in the air, or it attempts to elude the eagle by dodging. Like all the other member of the dog family, foxes are susceptible to a wide range of parasites and diseases. Most adults suffer to some degree from roundworms, tapeworms, and flukes.