We compared spatial and temporal patterns of resource use by feral and abandoned domestic dogs (Canis familiaris) on the Navajo reservation in Arizona and New Mexico. Community dumps provide locally abundant food resources utilized both by feral dogs and dogs abandoned at the dump site. Although population parameters were much the same for feral and abandoned dogs, the use of space varied distinctly and reflected behavioral differences in the way each population responded to the absence of human control, the need to acquire food, and the developmental state of pups. Temporal use of resources by feral dogs varied seasonally with the age of pups in one pack, but not in a second pack. Priority of access to local resources may be influenced by aggressive interactions among dogs at a dump. Barking may serve to warn dogs already present at a dump that competitors have arrived.