One former alpha female of the Bison Peak Pack was more than 13 years old when she was killed and eaten by a cougar. The death of an alpha offers a chance for one of its beta offspring to advance in coyote society. A younger male in the Bison Peak group took over after the alpha male was killed by a snow plow as he crossed the Lamar Valley road one winter day. But betas do not always wait until an alpha dies. In the other half, outside loners do the job.
Loners wander a social and biological netherworld in the unclaimed margins between territories.
Mature animals that lack a home, loners make up about a fifth of the coyote population and are ever vigilant for signs that an alpha is losing power or has died, offering a chance to take over. When an alpha is deposed, it generally takes up residence on the fringes of its old territory. Alpha males and females mate for life. Courtship begins in December in Yellowstone as the paired animals work in tandem to mark territorial boundaries with sprays of urine. The alphas mate in February, and pups are born in April in underground dens.