Reproductive biology of the Nile Soft-Shell Turtle, Trionyx triunguis, at the Seyhan River, Turkey (Testudines: Trionychidae)

Abstract

Several populations of the Nile Soft-shelled Turtle, Trionyx triunguis, are found along the Levantine and Turkish Mediterranean coast. The riverbanks of the Seyhan River hold one of the largest nesting populations. In a survey carried out between 2009 and 2018, a total of 209 nests were recorded (20.9 nests per season). Ninety-four percent of the nests were concentrated at one specific site where the nesting density was 4.18 nest/metre, but where most of the nests were predated by Red Fox (Vulpes vulpes) or Golden Jackal (Canus aureus). 137 nests (65.5%) with altogether 5,716 eggs were therefore transferred to a safe place, where 1,811 hatchlings emerged and were released at the nesting site at the Seyhan River. The average clutch size was 40.8±0.89 eggs. The mean hatching success in relocated nests was 34.6%. A total of 1,718 eggs (23.0%) were predated by mammalian predators. The remainder were developmentally interrupted eggs of early (37.9%), middle (4.3%), and late (6.5%) stages. It is discussed whether the high rate of loss of early stage eggs is related to the translocation process.