Chelonia

Number of Pages: 2Integrative BiologyGeological Science

Chelonia mydas

Number of Pages: 4Integrative BiologyGeological Science

Chelonia mydas

Number of Pages: 4Integrative BiologyGeological Science

Some aspects of the ecology of the leatherback turtle Dermochelys coriacea at Laguna Jalova, Costa Rica

The ecology and reproductive biology of the leatherback turtle (Dennochelys coriacea) was studied on a high-energy nesting beach near Laguna Jalova, Costa Rica, between 28 March and 8 June 1985. The peak of nesting was between 15 April and 21 May. Leatherbacks here measured an average 146.6 cm straightline standard carapace length and laid an average 81.57 eggs. The eggs measured a mean 52.12 mm diameter and weighed an average of 85.01 g. Significant positive relationships were found between the carapace lengths of nesters and their clutch sizes and average diameter and weight of eggs. The total clutch weighed between 4.02 and 13.39 kg, and yolkless eggs accounted for an average 12.4% of this weight. The majority of nesters dug shallow (<24 cm) body pits and spent an average 81 minutes at the nest site. A significant number of c1utcbes were laid below the berm crest. In a hatchery 42.2% of the eggs hatched, while in natural nests 70.2% hatched. The average hatchling carapace length was 59.8 mm and weight was 44.6 g. The longevity of leatherback tracks and nests on the beach was affected by weather. One nester was recaptured about one year later off the coast of Mississippi, U.S.A. Egg poaching was intense on some sections of the Costa Rican coast. Four aerial surveys in four different months provided the basis for comparing density of nesting on seven sectors of the Caribbean coast of Costa Rica. The beach at Jalova is heavily used by green turtles (Chelonia mydJJs) after the leatherback nesting season. The role of the Parque Nacional Tortuguero in conserving the leatherback and green turtle is discussed.(PDF file contains 20 pages.

Comparative features of isolated green turtle colonies

42 p. : ill., maps ; 24 cm.Includes bibliographical references (p. 41-42)."Data are presented on two genetically separate colonies of the Atlantic green turtle (Chelonia mydas mydas (Linnaeus)), one breeding at Tortuguero, Costa Rica, the other at Ascension Island in the South Atlantic. The two are compared with respect to reproductive behavior and periodicities and to various other features. The work at Ascension was undertaken because the periodic arrival of breeding schools at that oceanic island seemed clear evidence of a refined guidance process. Circumstances suggested that the island is the nesting center for the non-breeding green turtle populations of the coast of Brazil. Two Brazilian tag recoveries reënforce the assumption. Of turtles tagged during five seasons at Tortuguero, there have been 54 post-season recoveries, from all parts of the western Caribbean. The one return from outside the Caribbean came from Campeche, Mexico. Both renesting returns at Ascension and renesting and long-term returns at Tortuguero support previous evidence of strong site tenacity and discrimination in the species. Orientation tests in Florida, involving year-old green turtles of different backgrounds, show that animals of this age retain sea-finding sense to carry them to the water under strongly manipulated conditions on a strange shore. The migration problem is discussed in general terms, in the light of recent data, and hypothetical travel routes are proposed"--P. 40-41

Hawksbill turtle in the Caribbean Sea

29 p. : ill. ; 24 cm.Includes bibliographical references (p. 28-29)