results are conveniently laid out in a pie diagram (Fig. 1) . The 

 findings are surprising. Only about 5% of the eggs produce 

 viable hatchlings, but the most obvious photogenic sources of 

 mortality, the coat is digging up the eggs or the ever present 

 vultures, are not the major sources of low success rate. The 

 invisible predators, the fungi and microorganisms, do more 

 damage. Exactly why so many nests fail to produce hatchlings 

 remains to be determined but enough is clear to say that 

 microbiologists and pathologists rather than zoologists should 

 now be brought in to take this study to the next stage. 

 Destruction of nests by the turtles themselves is also as great 

 or greater than the toll taken by obvious predators. 



We hope that the full details of methods and data of this 

 study will be published in the archival peer-reviewed literature. 

 Despite the numerous positive things that could be said of this 

 work, as conservationists and managers, we should also note its 

 limitations. 



The study covers the fate of eggs up to the time of 

 hatching. Considerable natural mortality still occurs at later 

 stages of the life cycle, especially during movement from the 

 nest to the water and in the immediate offshore zone, but how 

 great this is, we do not know. 



The loss of eggs to erosion varies widely from year to year. 

 If estuaries behind the beach open up and flood the nesting 

 areas, as many as 3 0% of the eggs can be destroyed. On other 

 occasions only 2% are lost to erosion. Predicting mortality for 

 any particular arribada remains beset with uncertainties. 



Finally, and this will apply equally to the other examples 

 discussed below, one cannot generalize from this beach to other 

 nesting beaches. Nancite is an unusual arribada site in that the 

 extent of nesting space is severely limited by large rock masses 

 at each end of the beach. Even at other ridley arribada sites in 

 Costa Rica, for example, Ostional, where the beach is larger, 

 rotting of eggs is far less frequent. 



Example 2 : Green and leatherback turtles in Surinam 



A detailed and methodologically explicit study of the fate 

 of eggs of two species of sea turtles nesting in Surinam has been 

 carried out by Whitmore and Dutton (1985) . Although the hatch 

 rates of successful green turtle nests are relatively high 

 (80.4%), because 21% of their nests are laid below the spring 

 high tide line, the overall hatch rate is estimated at 63.5% 

 (Table 1) . In addition to nests laid below the spring high tide 

 line (judged to be doomed eggs and often relocated) , nests laid 

 above this line are nevertheless washed over by exceptionally 

 high seas without being totally destroyed. Whitmore and Dutton 

 (1985) kept records of such washovers and found that they were 



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