Fellows' research: Counting Free-Roaming Dogs in Rural India towards eliminating Rabies
03 Oct 2018
Dr. Abi Tamim Vanak, Intermediate Fellow
Ashoka Trust for Research on Ecology and Environment (ATREE), Bengaluru
Free-ranging domestic dogs are the main carriers of the deadly rabies virus, which kills more than 20,000 people in India yearly. Vaccination of dogs can prevent this disease from spreading. However, before any vaccination campaign can be conducted, the target population of dogs needs to be determined, as it is necessary to cover at least 70% of the dog population. However, because most dogs in India are free-ranging, counting them is not an easy task.
In our recently published study, we used techniques that were developed for estimating populations of wild animals, including tigers, for counting dogs on village streets. We adapted a popular method called the capture-recapture framework, by surveying fixed routes on motorcycles and photographing every dog that was sighted. This exercise was repeated for 7 days. We also used a novel technique based on Good-Turing theory, to determine if only two surveys were sufficient to provide a reliable estimate of the population. Based on our analysis, we found that direct count methods tended to underestimate the dog population, mainly because one cannot guarantee that every dog is sighted. Instead, more robust and analytically complicated methods such as the Capture-recapture framework take in to account this variability in the probability of “detecting” an animal, and thus provide more robust and statistically reliable estimates. However, these methods are time-consuming, since they require multiple surveys to generate reliable results. Instead, we found that the Good-Turing based Application SuperDuplicates method used just two surveys to provide equally reliable estimates of the dog population. This is important, since there is a tradeoff in effort between counting dogs and vaccinating them. Given the potential cost of any vaccination campaign, it is better to err on the side of caution and over-estimate the dog population, rather than conduct a rapid direct count that tends to grossly underestimate dog numbers.
A Comparative Study of Enumeration Techniques for Free-Roaming Dogs in Rural Baramati, District Pune, India. Harish Kumar Tiwari, Abi Tamim Vanak, Mark O'Dea, Jully Gogoi-Tiwari and Ian Duncan Robertson. Frontiers in Veterinary Science.