Capture-recapture data from two disparate breeding populations of Roseate Terns (Sterna dougallii) captured together as non-breeding individuals from 2002 to 2007 in the southern Great Barrier Reef, Australia were analyzed for both survival rate and recapture rate. The average annual survival rate for the two populations in the study area was estimated at 0.850. There is strong evidence that the average annual survival rate for the birds from the Asian population (S. d. bangsi) (0.901) is higher than that of the other population of unknown breeding origin (0.819). There was large variability in survival in both populations among years, but the average survival rate of 0.85 is similar to estimates for the same species in North America. The Cormack-Jolly-Seber models used in program MARK to estimate survival rates also produced estimates of recapture probabilities and population sizes. These estimates of population size were 29,000 for S. d. bangsi and 8,300 for the ‘unknown’ group. The population estimate for S. d. bangsi is double the visual estimates of the numbers in the study area and much larger than the documented numbers in the likely breeding areas, suggesting that many breeding sites are currently unknown.