Does Euphrates softshell turtle nest in unfavourable substratum? Description of nests from Euphrates River, Türkiye

Authors: YUSUF BAYRAKCI

Abstract: Nest site selection differs among species based on a characteristic crucial to the embryo's survival. The identified nest-site characteristics of the Euphrates softshell turtle highlight that these turtles, like their other soft-shelled relatives, highly prefer the sandy substrate, even pure sand, to nest. However, alteration and loss of natural habitats for many decades limited the suitable oviposition sites along the Euphrates River. This study presents the uncharacteristic nest-site choice and the nesting time of Euphrates softshell turtle for the first time. I discovered four nests, as well as six unhatched eggs in a nest on 20 August 2017. This discovery extends the known nesting season-end from early June to at least mid-August for the Euphrates River. The eggs were spherical, and their size was 28.38 (±0.2, 28.1-28.6) mm on average. The nesting substrate, consisting of only 51.8% sand, was substantially dissimilar to what was previously reported. Apart from the soil texture, the nest and its site characteristics concerning nest dimension, clutch size, egg size, and distance to the shoreline concord with what was formerly reported. I conclude that many anthropogenic alterations, such as sand mining and damming and hence the scarcity of suitable oviposition sites, may have caused location and time shift of breeding and forced the turtles to nest in these uncommon soil textures.

Keywords: Rafetus euphraticus, nest-site characteristics, soil composition, grain size

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