Reproductive Biology of the Loggerhead Sea Turtle, Caretta Caretta, in Dalyan Beach, Turkey, 2009

Abstract

The reproductive biology of loggerhead turtles, Caretta caretta, was studied at Dalyan, Turkey in 2009. This study was conducted between 18 June and 15 September 2009. During the breeding season, the night and morning patrols on the beach were performed. During night patrols, they were tagged and after that body measurements were taken. During morning patrols, the shape and pattern of tracks were noted and those tracks that resulted in nests were marked. During the hatchling emergence season, the numbers of hatchling tracks coming from each nest were counted daily, and the numbers of hatchlings reaching the sea were determined by following the tracks. A total of 1154 emergences were recorded with 330 (29%) resulting in nests. Of these nests, 5% occurred in May, 57% in June, 36% in July and 2% in August. The nest density of C. caretta at Dalyan was 70.2 nests/km. The mean clutch size at Dalyan during 2009 breeding season was 68.3 eggs (range 25-138, n = 123). The incubation period was on average 50.2 days (range 40-63, n = 123). All eggs were predated in 177 nests (53%), and some eggs were predated in 51 nests (15%) by foxes (Vulpes vulpes) and badgers. A total of 102 nests (31%) were completely protected so that no eggs were predated. The hatching success was 31.9%. While 5398 hatchlings (85.3% of the total number of hatchlings) were able to reach the sea, 175 hatchlings (2.8%) died inside the nest, 695 (11%) were predated by foxes, and 59 (1%) were predated by crabs. Nests that were threatened by the tide or human activities were transplanted to safe areas of the beach. Furthermore, metal gratings were placed on the nests to prevent fox predation.