Using Natural Marks to Estimate Free-Ranging Dog Canis Familiaris Abundance in a Mark-Resight Framework in Suburban Mumbai, India

Abstract

Free-ranging dogs ( Canis familiaris) are a major conservation issue in the tropics and adopt many ecological roles, alternatively functioning as predators, prey, or competitors of wildlife in diverse environments. Dogs are also potential reservoirs of disease that can be transmitted to both wildlife and people. Therefore a range of management interventions have been suggested to control dog populations. In order to monitor interventions to decrease dog populations, estimates of their population size are important and such methods need to be time- and cost-effective. We describe here a potential method that uses natural marks on dogs along with counts of non-marked individuals in a mark-resight framework to estimate the abundance of free-ranging dogs in a suburban area in India. Using the logit-normal mixed effects estimator to incorporate the effects of individual resighting heterogeneity, we found a total ( Nj) of 680.64 ± 34.06 (95% CI = 617.22 – 751.35) dogs in the study area, with an overall mean resighting probability of 0.53 ± 0.03 (95% CI = 0.47 – 0.58). This corresponds to a density estimate of 57 dogs km−2 (CI = 51 – 63). Given that certain assumptions are met, this method may be useful to estimate abundance of dogs where other kinds of marks may be unavailable or impractical. This method may be applied to other species of feral animals as well, where some proportion of a population has distinct natural marks.