Howling by coyotes (Canis latrans):: variation among social classes, seasons, and pack sizes

From January 1991 to June 1993 we observed 54 coyotes (Canis latrans) for 2507 h in Yellowstone National Park, Wyoming, during which we observed 517 howling events. Among coyotes of different types of social organization (resident versus transient), members of resident packs initiated or participated in howling events, while transient individuals were never observed howling (n = 51 h of observation). For members of resident packs, alpha coyotes spent more time howling and had a higher rate of howling events than beta coyotes and pups; beta coyotes and pups howled similarly. The percentage of time and the rate of howling events typically peaked in the dispersal and breeding seasons, with the lowest rate of howling during pup rearing. Social rank and season did not influence the length of howling events. Pack size did not affect howling rates among individuals in a pack or the alpha pair. With respect to space-use patterns, coyotes in resident packs howled more frequently than expected along the periphery of the territory than in the core area. We concluded that, like wolves (Canis lupus), all coyotes in the resident pack did not contribute equally to howling duties; alpha coyotes howled more than all coyotes. Howling by coyotes appears to serve a territorial spacing function that is mainly performed by the alpha pair of the resident pack.