Habitat selection and range size of grass snakes Natrix natrix in an agricultural landscape in southern England

Abstract

The range sizes and habitat preferences of nine adult European grass snakes (Natrix natrix) were determined from radio-tracking data obtained within a landscape of mixed deciduous woodland and pastoral fields in southern England. These data were analysed using RANGES7v0.81 software. Concave polygons resulted in overall individual range size estimates that varied between 0.18-9.41 ha. However, for individuals that were radio-tracked for more than one season, annual range size estimates ranged between 1.29 ha and 3.56 ha and some snakes shifted their range between seasons. Grass snakes showed a strong preference for habitat boundaries and interfaces and an avoidance of woodland, and fields that were used for grazing. The attributes common to habitats that snakes preferred were a combination of basking site availability and a close proximity to relatively dense vegetation that offered potential protection from predators. The attributes common to habitats that snakes avoided were a lack of basking sites in woodland, and cover, in fields. Grass snakes selected banks as hibernation sites, the majority of which were within woodland. © 2009 Brill Academic Publishers.