On the Howstuffworks website, for example, you can read that wolves follow "an incredibly sophisticated group hierarchy ... The pack structure is said to include a "beta wolf" who is the deputy ...

The wolf pack is a fundamental unit within the natural hierarchy of these apex predators. Typically, a wolf pack consists of the breeding pair—the alpha male and female—and their offspring.

In every pack there’s a male and female wolf that rank higher than the others ... Previously, it was thought that the alpha pair ascended the pack hierarchy through dominance and aggression ...