The ecology and migrations of sea turtles, 7 the west Caribbean green turtle colony

The present report is a summary and preliminary analysis of data on the green turtle, Chelonia mydas, that has been collected during a 22-year tagging program at Tortuguero, Costa Rica, 52 miles north of the Caribbean city of Puerto Limon. It is the first general account of Tortuguero results since 1960. From 1955 through the 1976 season, approximately 12,000 female green turtles have been tagged on the nesting beach. Of these, 2522 have been seen in subsequent years; 1412 of them as return migrants and 1110 on distant forage grounds or in migration. No turtle tagged at Tortuguero has ever been reported from any other nesting shore. The paper is concerned mainly with the migratory and behavioral ecology of the colony and with interseasonal changes in the nesting population. Results are presented in five sections, as follows: (1)Migratory geography and speed of travel: of 1110 long-distance, postseasonal recoveries of Tortuguero tags 957 have come from the Miskito Cays and adjacent parts of Miskito Bank off the Nicaraguan coast. Smaller numbers of recoveries cluster in Colombia, Panama, and Mexico. Analysis of monthly recovery frequencies in Nicaragua, and of periods of time elapsed between tagging and recapture, reinforce the assumption that Miskito Bank is a resident foraging range and not merely a travel station. Migratory travel speeds based on tag recoveries are compared with those recorded in the literature. (2)Nesting and renesting: The average number of nestings by a Tortuguero turtle during a season at the breeding shore is 2.8; the recorded maximum is seven, although eight probably occur occasionally.