Canids display a wide diversity of social systems, from solitary to pairs to packs, and hence they have been extensively used as model systems to understand social dynamics in natural systems.Among canids, the dog can show various levels of social organization due to the influence of humans on their lives. Though the dog is known as man's best friend and has been studied extensively as a pet, studies on the natural history, ecology and behaviour of dogs in a natural habitat are rare. Here we report results of an extensive population-level study conducted through one-time censuses in urban India to understand the ecoethology of free-ranging dogs. We built a model to test if the observed groups could have been formed through random associations while foraging. Our modeling results suggest that the dogs, like all efficient scavengers, tend to forage singly but also form random uncorrelated groups. A closer inspection of the group compositions however reveals that the foraging associations are non-random events. The tendency of adults to associate with the opposite sex in the mating season and of juveniles to stay close to adults in the non-mating season drives the population towards aggregation, in spite of the apparently random nature of the group size distribution. Hence we conclude that to be or not to be social is a matter of choice for the free-ranging dogs, and not a matter of chance.

Indian free-ranging dogs live in a carbohydrate-rich environment as scavengers in and around human settlements. They rarely hunt and consequently do not encounter rich sources of protein. Instead they have adapted to a diet of primarily carbohydrates. As descendents of the exclusively carnivorous wolves, they are subjected to the evolutionary load of a physiological demand for proteins. To meet their protein needs they resort to a thumb rule -if it smells like meat, eat it. Pups face high competition from group and non-group members and are in a phase of rapid growth with high protein demands. Following the thumb rule, then they can acquire more protein at the cost of increased competition and reduced supplementary non-protein nutrition. However, if the mother supplements their diet with protein-rich regurgitates and/or milk, then the pups can benefit by being generalists. Using a choice test in the field we show that while adults have a clear preference for meat, pups have no such preference, and they even eat degraded protein eagerly. Thus the thumb rule used by adult dogs for efficient scavenging is not innate, and needs to be learned. The thumb rule might be acquired by cultural transmission, through exposure to meat in the mother's regurgitate, or while accompanying her on foraging trips.

22Animals that scavenge in and around human localities need to utilize a broad range of 23 resources. Preference for any one kind of food, under such circumstances, might be 24 inefficient. Indian free-ranging dogs, Canis lupus familiaris are scavengers that are heavily 25 dependent on humans for sustaining their omnivorous diet. The current study suggests that 26 because of evolutionary load, these dogs, which are descendents of the decidedly carnivorous 27 gray wolf, still retain a preference for meat though they live on carbohydrate-rich resources. 28The plasticity in their diet probably fosters efficient scavenging in a competitive 29 environment, while a thumb rule for preferentially acquiring specific nutrients enables them 30 to sequester proteins from the carbohydrate-rich environment. 31 32

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