Stray Dogs Research Papers - Academia.edu (original) (raw)

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. Free-ranging dogs (Canis lupus familiaris), descendants of pack-living gray wolves (Canis lupus lupus), underwent domestication and became a ubiquitous part of human habitations 1–6. They have managed to survive as scavengers 7,8 , co-existing with humans in urban as well as rural habitats. Openly disposed human leftovers, domestic animal carcasses and food received from humans through begging are the major sources of their diet 9,10. While free-ranging dogs depend heavily on humans for sustenance and interact regularly with humans, they are often considered a menace for being carriers of pathogens and zoonosis 11–13. Sometimes people are attacked by dogs on streets, especially at night when a motor vehicle passes the territory of free-ranging dogs. These free-ranging dogs are often considered as a major threat to human health for being reservoirs of rabies, canine distemper and parvovirus 11–13. For example, 99% of all human deaths caused by rabies occur in developing countries, with the majority of cases resulting from dog bites 10. Exponential growth of the human population facilitates population growth of free-ranging dogs 13. It becomes a serious problem for health management in developing countries where the movement and reproduction of free-ranging dogs are not entirely controlled by humans. Vaccination and animal birth control programmes are expensive, and likely to be effective only if practiced on a large scale 14,15. Improved food waste management could also help to reduce free-ranging dogs in and around human settlements 16. However in developing countries such management becomes all the more difficult, and management decisions need be founded on an understanding of free-ranging dogs' ecology and population dynamics, for which scientific data is lacking 17,18. Free-ranging dogs in India are facultatively social where group dynamics are strongly influenced by social interactions during mating and denning seasons 19. They have been reported to breed once a year 20 although two distinct mating seasons have been observed (Sen Majumder and Bhadra, 2015). Mothers, along with other group members show significant amount of cooperative behaviour towards new born pups, which is expected to lead to higher survival rates 21. Pups start to be weaned around 8 weeks of age, which also marks the onset of conflict over resources with the mother 22,23. The early life of dogs is divided into the pup (0–3 months) and juvenile (3–6 months) stages, and sexual maturity sets in between 6–9 month of age 24. Dispersals are common in the adult (after attaining sexual maturity) and sub-adult (after 6 months to the attainment of sexual maturity) stages 24 , making the social organization quite dynamic. Although there is a growing body of literature on the behaviour and cog-nitive abilities of dogs 26–29 , detailed study of the structure and dynamics of natural free-ranging dog populations are lacking. Life-history comparison of mammals have suggested that juvenile mortality is more highly correlated with life-history traits than adult mortality, and the age of the onset of reproduction in females is strongly