marine algae featuring extensively in the diet of olive ridleys 

 in Indian and Sri Lankan waters. 



Reproductive ecolocry ; The reproductive habits of the olive 

 ridley show many unusual features. The small size and light 

 weight of the species facilitates its utilization of flat wide 

 beaches of the type that may be eschewed by turtles of greater 

 weight. The nesting excursions are usually but not always 

 nocturnal and the terrestrial gait is relatively rapid, involving 

 alternating movements of limbs. A nesting ridley is usually 

 ashore for only 45 to 50 minutes. The nests are rather shallow 

 and contain, on average, about 105 eggs, about 3.7 to 4.0 cm in 

 diameter. After laying the eggs and filling in the nest cavity, 

 the olive ridley thumps the sand over the nesting site by means 

 of a vigorous, side-to-side rocking action of the shell. Nesting 

 may occur two or three times within a season, and, unlike sea 

 turtles of other genera, nesting in successive seasons occurs 

 frequently, and possibly is the norm. 



Although olive ridleys often nest in solitary fashion or in 

 small groups, the species is famous for a much more spectacular 

 nesting style. In certain places in the world (see 

 Distribution ) , nesting occurs in an extraordinarily aggregated 

 fashion, literally tens of thousands of individuals emerging in 

 the course of a single night on the same short stretch of beach. 

 Concentrations of nesting turtles may be so high that many 

 turtles destroy the nests of their predecessors in the course of 

 their own nesting attempts, and the resulting mix of sand, 

 eggshells, spilled egg contents, and ensuing fungi and 

 microorganisms may constitute a very poor incubation medium. The 

 cues to which these large aggregations of turtles are responding 

 when they come ashore are still somewhat mysterious, but in some 

 areas meteorological conditions (especially wind) appear to be 

 important . 



The only "arribada," or aggregated nesting effort, in the 

 Atlantic system was a very small one at Eilanti, Surinam, where, 

 during the 1960s, up to 500 turtles might nest in the course of a 

 good night. During the last few years, however, this aggregation 

 has been reduced to perhaps 10 percent of the 1960s' level, 

 prompting great concern for the future of the South Atlantic 

 population of the olive ridley. On the other hand, the collapse 

 of this arribada may possibly be related to the progressive 

 buildup of a mud bank in front of the beach, making access by the 

 turtles increasingly difficult, and informal reports have been 

 received that groups of at least a few hundred olive ridleys may 

 have started to nest to the east, near Kourou, French Guiana. 



Major threats to survival ; The olive ridley is still the 

 most numerous sea turtle in the world, but it qualifies as an 

 endangered species nonetheless in view of the enormous levels of 

 capture in recent years and to some extent up to the present, at 



27 



