Radiotracking of Coluber viridiflavus Using External Transmitters

Abstract

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 im- plantation. 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. The use of radiotracking for studying snake movements and home range is hampered by the difficulty of applying radiotransmitters to these animals. Nevertheless, after Fitch and Shirer's (1971) study of some Colubridae and Crotalidae, other authors used this method on snakes. One