Radiotracking of Coluber viridiflavus using external transmitters

A new technique of attaching transmitters to snakes was used to study movements of the colubrid Coluber viridiflavus in central Italy. The transmitter and battery were encased in polyesteric resin, hand-shaped, and then attached dorsally to the body behind the cloaca by two nylon threads, each strung through a rubber tube, inserted transversely under the dermis. This external attachment of the transmitter is feasible and overcomes the problems encountered with forced ingestion or surgical implantation. A preliminary analysis of the movements of 11 snakes radiotracked at different times for two years revealed that Coluber viridiflavus has a monofocal activity pattern, characterized by loops radiating out from a permanent den used also as a hibernaculum. Males make longer and longer-lasting loops than do females, but in both sexes loop length and duration also depend on season.