Population Estimates of the Nose-horned Viper Vipera ammodytes (Linnaeus, 1758) (Reptilia: Viperidae) from Five Populations in Bulgaria

摘要

Five populations of Vipera ammodvtes in Western Bulgaria located along a latitudinal gradient were studied using the Capture-Mark-Recapture method. Sex ratio among subadults and juveniles was approximately 1:1 but it was difficult to be determined in adults due to methodological biases caused by differences in catchability of males and females during the active season. The marked individuals had high survival rate, but capture probability was low. From north to south, the established numbers and densities of the species in the studied areas were as follows: Karlukovo - 796 individuals, with density 5.78 ind./ha, Lakatnik - 319 individuals, with density 1.59 ind./ha, Balsha - 635 individuals, with density 4.12 ind./ha, Bosnek - 296 individuals, with density 0.73 ind./ha, Kresna Gorge - 245 individuals, with density 2.07 ind./ha. Differences in movement rate between sexes were observed, with adult males being more mobile than females. During gestation, pregnant females became very static and usually kept close to the hibernating areas. After parturition, the neonates stayed close to these areas until the beginning of hibernation.