Uticaj variranja osobina životne istorije na vijabilnost populacije šumske kornjače Testudo hermanni Gmelin (Chelonia: Testudinidae) iz istočnog dela areala

Abstract

During the five consecutive years (2010-2014), in the local population of the eastern Hermann's tortoise (Testudo hermanni boettgeri) in the vicinity of Kunovica village near Nis, the variation of selected life-history parameters, population structure and some additional characteristics reflecting the population status were observed and measured. The existence of sexual size and shape dimorphism has been confirmed, followed by a slight variation in the body mass condition index of adult tortoises during consecutive years of monitoring, which could indicate a stable health status of the population. Adult sex ratio deviates from the otimum, so that the females were more numerous than males. Determining the prеcise age structure was not possible. Also, a wide range of variation in the age of achieving sexual maturity has been observed. The average clutch size fits into the range of values reported in the literature. The average survival rate of adult individuals was high and no differences in survival between sexes were found, also differences between sexes in the size of the area of movement were not determined. An analysis of the viability of the hypothetically isolated Hermann's tortoise population in Kunovica, within the experimental area, showed that such a population is not viable. Accordingly, the minimum viable size of this population has not been determined, but it has been established that an increase in the carrying capacity of the habitat leads to a significant reduction of the extinction. Among the simulated parameters, the most critical one for long-term survival is the very disturbed sex ratio at birth. In contrast, the earlier sexual maturation and the younger age of the first reproduction, could approach the status of a viable for this population within the next hundred years. It has been shown that a triple increase in the carrying capacity of the habitat can increase the probability of survival for a third what, with additional monitoring, would allow the long-term survival of this population of Hermann's tortoise.