The photo mark and recapture technique was employed to estimate the stray dog population in this study. The estimations were based on two observations per area within 1 day of observation. The estimation from each area was performed 2 times at approximately 6 months apart. On each observation day, the research team consisted of three people who observed and performed visual marking by photography, counting, and note-taking for age and sex identification. The observation trial was designed according to the preliminary trial analysis from each area. Dog identity, age, and sex were evaluated independently by the observers. Dogs were classified into four age levels: Old adults, adults, juveniles, and puppies. This classification was based on visual observations of the general appearance, determination of tooth wear if the dog could be handled, and interviews with residents who fed the dogs [14 ]. The first photo mark session was performed in the early morning (0600). The second or recapture session was performed along the same route in the afternoon (1700). The total population size (N) of dogs was estimated from the number of dogs in the first photo mark session (n1), the number of dogs in the recapture session (n2), and the number of marked dogs from the second session (m2) using formula 1. The lower and upper 95% confidence limits for the total population size (LCL and UCL, respectively) can be estimated with formula 2 [15 ].
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