This data and code accompany the manuscript "Small population size and possible extirpation of the threatened Malagasy poison frog Mantella cowanii". The data were collected using photograph capture-recapture at three sites in the central highlands of Madagascar. In Part 1, the script implements robust design capture-mark-recapture models in program MARK through the RMark interface to estimate population sizes and annual survival probabilities. In Part 2, it estimates the number of surveys needed to infer absence at sites where we did not detect the frog.