SHELTER REQUIREMENTS 



Not known. 



NESTING OR BEDDING 



With the exception of occasional females 

 known to nest on Padre Island, Texas (Werler 

 1951), the entire population nests on about 24 

 km of beach between Barra del Tordo and Ostio- 

 nal in State of Tamaulipas, Mexico. They prefer 

 sections of beach backed up by extensive swamps 

 or large bodies of open water having seasonal, 

 narrow ocean connections (Pritchard and Mar- 

 quezM. 1973). 



A well-defined and elevated dune area is ne- 

 cessary for successful nesting. Pritchard and Mar- 

 quez M. (1973) suggest that this provides a land- 

 mark for the turtle to dig a nest that will be above 

 mean high tide. 



RITUAL REQUIREMENTS 



Not Known. 



OTHER CRITICAL ENVIRONMENTAL 

 REQUIREMENTS 



Females land in large numbers only when 

 strong or moderate north winds blow. Pritchard 

 (1976) suggests that this may cover the turtle's 

 tracks and/or dissipate nesting smell. 



POPULATION NUMBERS AND TRENDS 



In 1947, a Mexican, Sr. Herreva, filmed nest- 

 ing. Estimates based on this film put the breeding 

 population at 40,000 at that time. Despite the 

 protection of the nesting beach since 1966, the 

 breeding population now is reported to be be- 

 tween 1,500 and 3,000 adults, with only about 

 500 females nesting during the 1978 season 

 (Anon. 1978). 



The 1947 film shows what is believed to be 

 the entire breeding population swarming ashore at 

 once. Such a massive landing is called an 'arriba- 

 da.' R. Marquez M. (personal communication) has 

 observed nesting since 1966 and reports that the 

 number within arribadas is declining. In 1976, the 

 largest was made up of approximately 150 fe- 

 males, and there are usually between five and 

 seven arribadas per season. 



Failure to rebuild population numbers in spite 

 of beach protection may result from low survivor- 

 ship (Pritchard 1976). 



REPRODUCTION 



Ridleys nest from April to June, during which 

 time turtles appear off Tamaulipas. After strong 

 winds, females swarm ashore to nest in daylight 

 hours. A female nests a maximum of three times a 

 season with an intemesting interval of 10 to 28 

 days. Individuals often nest annually with an ave- 

 rage clutch size of 110 eggs (Pritchard 1969a, 

 Lund 1976). 



Copulation takes place offshore near the 

 nesting beach, and some pairs remain embraced 

 for hours. Black-and-white photographs of court- 

 ship and mating activities appear in Bustard 

 (1973). 



MANAGEMENT AND CONSERVATION 



Since 1966, the Mexican government has con- 

 ducted a tagging program for adults at Rancho 

 Nuevo and has protected the beach with military 

 personnel. About 330 clutches of eggs have been 

 relocated annually to fenced compounds (R. Mar- 

 quez M. personal commnication). 



Pritchard (1976) argued for the perfection 

 and deployment of a modified trawl net to pre- 

 vent the incidental catch of sea turtles, and work 

 on this project is well underway by the U.S. 

 National Marine Fisheries Service. 



Lund (1974) reported on a private effort to 

 stock Texas waters with eggs taken from the Ran- 

 cho Nuevo beach in Mexico. In 1978, a multi- 

 agency effort was initiated by the U.S. Fish and 

 Wildlife Service, National Park Service, National 

 Marine Fisheries Service, and Texas Parks and 

 Wildlife Department in coordination with the 

 Mexican government (Anon. 1978). This program 

 incorporates a wide variety of techniques, in- 

 cluding more intensive protection for the Rancho 

 Nuevo beach, an attempt to establish a breeding 

 population at Padre Island National Seashore by 

 transplanting 2,000 eggs annually, and head- 

 starting of 2,000 hatchlings from the Rancho 

 Nuevo beach and the hatchlings from Padre Island 

 at the NMFS laboratory in Galveston, Texas 

 (Anon. 1978,Wauer 1978). 



Marquez M. (1976b) recommends formation 

 of seven natural reserves for Mexican coasts, 

 which include Playa de Rancho Nuevo, Tamauli- 

 pas, the Kemp's ridley's nesting beach.. 



AUTHORITIES 



Archie Carr 



Department of Zoology 

 University of Florida 

 GainesvUlcFL 32611 



