Diet composition changes correlated with body size in the Smooth snake, Coronella austriaca, inhabiting lowland heath in southern England

The diet of Smooth snakes (Coronella austriaca) inhabiting lowland heath in southern England was studied over a nine-year period (2004-2012) by analysing 226 faecal samples obtained from 19 females and 41 males of varying age/size from juveniles to sexually mature adults. The main prey species belonged to the families Lacertidae (48%), Soricidae (32%) and Muridae (13%) with the remaining 7% comprising Anguidae (6%), Colubridae (0.5%) and Bufonidae (0.5%). Small mammals were absent from the diet of the smallest snakes but were a major component in the diet of large snakes. Lacertids were a major component of the diet of juvenile snakes whilst they formed a progressively smaller part of the diet of adult snakes. The data demonstrates a shift in diet, with increasing snake size, from Lacertids to small mammals. The highest number of small mammals was found in the diet during the early part of the activity period (April-June) with females apparently preying mainly upon Lacertids in late summer (August-October). A detailed understanding of the diet of C. austriaca, and how it changes with increasing snake body size, may have implications for the conservation of the species in the UK. Management of heathland that damages the preferred habitat of small Lacertids, the main prey of the smallest juvenile snakes, is likely to have a negative impact on recruitment and, as a consequence, a negative impact on the survival of C. austriaca populations.