Dynamics of a Western Anatolian population of Natrix natrix and Natrix tessellata (Serpentes: Natricidae)

Due to their secretive nature, snakes are the most challenging animal group for monitoring. Nevertheless, population size estimates are indispensable to accurately determining conservation status and management strategies. We used passive integrated transponder (PIT) tags to track aquatic snakes Natrix natrix and Natrix tessellata in Lake I????kl??, Denizli province, Turkey. 304 N. natrix and 1563 N. tessellata specimens were captured and marked over the four-year sampling period. Of the marked individuals, 14 N. natrix and 97 N. tessellata were recaptured at least once. The three-year average population size was estimated at 1940 ?? 1055 for N. natrix, and 10,146 ?? 1679 for N. tessellata. The annual survival rate is 0.57 ?? 0.19 (range = 0.22???0.86) and 0.37 ?? 0.06 (0.27???0.50) for N. natrix and N. tessellata, respectively. In April, which is the most active month for water snakes, 60% of the snakes were captured. This study represents the first comprehensive demographic estimates of Natrix species in Turkey.