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.

Queens and workers are not morphologically differentiated in the primitively eusocial wasp, Ropalidia marginata. Upon removal of the queen, one of the workers becomes extremely aggressive, but immediately drops her aggression if the queen is returned. If the queen is not returned, this hyper-aggressive individual, the potential queen (PQ), will develop her ovaries, lose her hyper-aggression, and become the next colony queen. Because of the non-aggressive nature of the queen, and because the PQ loses her aggression by the time she starts laying eggs, we hypothesized that regulation of worker reproduction in R. marginata is mediated by pheromones rather than by physical aggression. Based on the immediate loss of aggression by the PQ upon return of the queen, we developed a bioassay to test whether the queen's Dufour's gland is, at least, one of the sources of the queen pheromone. Macerates of the queen's Dufour's gland, but not that of the worker's Dufour's gland, mimic the queen in making the PQ decrease her aggression. We also correctly distinguished queens and workers of R. marginata nests by a discriminant function analysis based on the chemical composition of their respective Dufour's glands.

Free-ranging dogs are a ubiquitous part of human habitations in many developing countries, leading a life of scavengers dependent on human wastes for survival. The effective management of free-ranging dogs calls for understanding of their population dynamics. Life expectancy at birth and early life mortality are important factors that shape life-histories of mammals. We carried out a five year-long census based study in seven locations of West Bengal, India, to understand the pattern of population growth and factors affecting early life mortality in free-ranging dogs. We observed high rates of mortality, with only ~19% of the 364 pups from 95 observed litters surviving till the reproductive age; 63% of total mortality being human influenced. While living near people increases resource availability for dogs, it also has deep adverse impacts on their population growth, making the dog-human relationship on streets highly complex.

Past research has suggested that a variety of factors, phylogenetic and ontogenetic, play a role in how canines behave during problem-solving tasks and the degree to which the presence of a human influences their problem-solving behaviour. While comparisons between socialized wolves and domestic dogs have commonly been used to tease apart these predictive factors, in many cases a single dog population, often pets, have been used for these comparisons. Less is understood about how different populations of dogs may behave when compared with wolves, or with each other, during an independent problem-solving task. This experiment compared the independent persistence of four populations of canines (two groups of pet domestic dogs, a group of free-ranging domestic dogs, and human-socialized wolves) on an independent problem-solving task in the presence of an on looking human. Results showed that wolves persisted the most at the task while free-ranging dogs persisted the least. Free-ranging dogs gazed at the human experimenter for the longest durations during the task. While further research is needed to understand why these differences exist, this study demonstrates that dogs, even those living outside human homes as scavengers, show comparatively low levels of persistence when confronted with a solvable task in the presence of a human as well as significantly greater duration of human-directed gaze when compared with wolves.

Generally the main component of fishy flavor is considered to be trimethylamine. On the other hand, carbonyl compounds, produced from oxidation of polyunsaturated fatty acid by lipoxygenase or by autoxidation, might have some contribution to the fishy flavor. Since sardine skin contains high levels of polyunsaturated fatty acids and lipoxygenase, carbonyl compounds may be generated more easily than trimethylamine. In this study, volatile flavor compounds of sardine were analyzed by gas chromatograph-mass spectrometry and gas chromatograph-olfactometry combined with solid phase microextraction. Then, the flavor components that contribute to fishy flavor were identified. At normal pH (6.2), trimethylamine was not detected or sensed from the fresh sardines. When the pH was raised, the amount of trimethylamine became higher. Trimethylamine flavor was weak at pH 9 and strongly sensed at pH 11 or higher. On the other hand, 33 other compounds were positively or tentatively identified, including 8 hydrocarbons, 5 ketones, 1 furan, 1 sulfur compound, 12 aldehydes, and 6 alcohols in fresh sardines. Among them, 2,3-pentanedione, hexanal, and 1-penten-3-ol were the main components. Forty-seven flavors were detected by gas chromatograph-olfactometry. Among them, paint-like (1-penten-3-one), caramel-like (2,3-pentanedione), green-like (hexanal), shore-like ((Z)-4-heptenal), citrus note (octanal), mushroom-like (1-octen-3-one), potato-like (methional), insect-like ((E,Z)-2,6-nonadienal), and bloody note (not identified) were strongly sensed. From the aforementioned results, it can be concluded that these compounds rather than trimethylamine contributed to fresh sardine flavor.