A variety of the social system in the Canidae was reviewed with the comparison of mating system, social behaviour, and feeding ecology in the context of evolutionary perspective. Five types of social system were identified according to the periods of pair formation, the degrees of paternalmaternal care and the dipsersion patterns of offspring. In types I to III, a male-female pair is the basic social unit of the system accompanied with their offspring and/or non-dispersal offspring. Types IV and V are unique, compared with the former three, while their basic social unit is also the mating pair. Canids used a wide variety of food items from berries to large mammals ; this was caused by their opportunistic feeding strategies to the change of resource availability. The longterm monogamous mating system among canids would have evolved through a trait that males are less successful with two mates than with single, in their physiological constraint of reproduction. Canids social systems varied also by the utilization patterns of resources among parents and their offspring.
