Coyotes are predators, common throughout North and Central America. The coyote has a narrow skull and jaw, so it lacks the mandibular strength to hold the large prey species that wolves feed on. However, the coyote has a larger brain case than the wolf. Coyotes and wolves are able to cross-breed and produce live offspring, called "coywolves." The coywolf offspring are apparently fertile themselves, but are at an evolutionary disadvantage when compared to wolves, since they still lack the jaw strength to feed on deer and moose. Coyote social structures are flexible. Coyotes can be solitary or live with a nuclear family, and informal groups of unrelated coyotes will sometimes band together temporarily.