Two populations of the tropical frog, Rana erythraea, on southern Negros Island, Philippines, were studied over a four-year period, and a third population over an eight-month period. The capture-mark-recapture technique was used. Females reach a maximum size of ca 75 mm snout-vent length and grow more rapidly than males (max. ca 48 mm). Females attain a length of 57-62 mm near the end of the first year following metamorphosis, growth averaging ca 11 mm per 30 days immediately following metamorphosis and decreasing to less than 1 mm per 30 days toward the end of the first year; males attain a length of ca 43 mm by the end of the first year, growth averaging ca 6 mm per 30 days immediately following metamorphosis and decreasing to about 1 mm per 30 days at the age of 6-7 months. Males attain sexual maturity 6-7 months after metamorphosis (ca 35-36 mm snout-vent length) and females approximately 9 months after metamorphosis (ca 50-60 mm). Recapture data indicate that the maximum life span in the two populations studied over a period of years was 3-4 years. The average proportion of frogs 1-plus to 3-plus years of age ranged from about 22-30%, being consistently but not significantly different in the two populations. Calculated minimum survival for one population was about 0.05 for the four-year period; for the other, the minimum survival ranged from about 0.015 to 0.03. The populations exhibited a consistently higher, though variable proportion of mature males; but the male-female ratio differed significantly from a 1:1 ratio for only one. Some similarities and differences in the adaptations of tropical and north-temperate species of the genus Rana are discussed.
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Brown et al. (1970) studied this question.