Street dog deaths largely human-influenced: Study

Kolkata: A high percentage of street dog deaths were influenced by humans, says a new study, which also notes how human activities impact the sex ratio of the free-ranging dog population.

In a five-year-long census based study in seven locations of West Bengal, researchers from the Indian Institute of Science Education and Research, Kolkata (IISER, Kolkata) attempted to understand the pattern of population growth and factors affecting early life mortality in free-ranging dogs.

"In 95 observed litters with 364 pups, only 19 percent of them survived the reproductive age. We found 63 percent of total mortality was human influenced, either directly or indirectly," Anindita Bhadra of the department of biological sciences at IISER, Kolkata told IANS.

Published in Nature Scientific Reports on January 25, the analysis said that "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".

Further, the study shows how humans are also responsible for a skewed sex ratio in dog population.

"People preferentially remove male pups from the population, and our simulation shows that this leads to higher mortality of females due to accidents, due to the sheer skew in the numbers of male and female pups/juveniles in the resulting population.

"Humans not only are responsible for a high proportion of the mortality of free-ranging dogs in early life, but also cause a skew in the sex ratio of the cohort that attains sexual maturity," Bhadra said quoting from the report.

The broader picture that emerges is that understanding population dynamics is crucial for successful dog control measures, said Bhadra.

"Qualitatively, when we looked around, we saw dog numbers are not increasing every year. Biologically growth rate is not that high. What shocked us a lot was that in many places, people were mixing poison with food and feeding the dogs. Entire litters were washed out. This happens a lot," she added.