The social organization of free-ranging urban dogs. I. Non-estrous social behavior

Abstract

Free-ranging domestic dogs (Canis familiaris) in Newark, New Jersey (U.S.A.), were studied during summer (1978) and winter (1978–1979) months. Population densities of approximately 400 dogs per square mile and a sex ratio of 3 males: 1 female were found for each of three study areas. Free-ranging dogs were typically large, owned individuals; strays were a monority. Of four different group types identified in this study (familiar, unfamiliar, people-mediated and estrous), the first three are described. The social organization during non-breeding periods was characterized by a majority of solitary individuals. The relatively few groups observed rarely contained more than two individuals. Familiarity between dogs was the primary basis of sociality, although the distance a dog was from its home-site, its body size, age and ownership status also influenced social behavior. There was no seasonal variation in these patterns. Aggression was rare and mutual avoidance was the primary spacing mechanism. However, of those agonistic interactions that did occur, unfamiliar dogs were involved 5–15 times more frequently than familiar dogs.

Home-range movements of individuals were largely restricted to areas around the home-site. Home-range size was correlated to a dog's ownership status much more than body size. There was no evidence of territoriality.

Resources such as food and shelter influenced the social organization by concentrating individuals in areas where these were available. Major, predictable changes in available food had no effect on social behavior. Likewise, environmental parameters such as human presence and weather conditions generally influenced dog behavior indirectly.