Factors influencing intergroup agonistic behaviour in free-ranging domestic dogs (Canis familiaris)

We investigated the effects of sex, age, season and competitive context on the intergroup agonistic behaviour of free-ranging dogs (Canis familiaris). Data were collected in different places to record competitive cooperative behaviour during intergroup conflicts. Observations of 21 free-ranging dogs belonging to four neighbouring groups were made in Katwa town, India. Throughout the 12-month study period, 85 % of all intergroup agonistic interactions recorded were aggressive and 15 % submissive. Intergroup aggressive interactions were more frequent during the late monsoon months when the females were in oestrus, while submissive interactions reached a peak during the winter months when the females were lactating. Adult dogs, particularly males, displayed a higher rate of aggressive behaviour than other age classes, whereas juvenile dogs, particularly males, displayed the highest rate of submissive behaviour. Male dogs were observed to perform more agonistic behaviours in mating contexts and at the boundaries of their territories, whereas female dogs displayed more agonistic behaviours in feeding contexts and in the vicinity of the den. Both aggressive and submissive patterns displayed by the dogs varied with the competitive contexts. The most frequently observed category of aggressive behaviour was 'barking, growling and snarling' and submissive behavioural patterns were displayed frequently by 'lips retracted in a submissive grin'. The striking feature of this study was that in most cases, more than one dog participated in aggressive conflicts. Such cooperative defense predominantly occurred at the boundaries of territory. Group home range size was largest during the late monsoon months and during the winter months.