A Radiotelemetric Study of Spatial Relationships in Some Common Snakes

Radio transmitters embedded in silicone rubber in elongate, oval, smooth-surfaced packages 50 x 21 x 14 mm or a little larger, were forcefed to 67 snakes of eight species (a 68th snake had an abdominally implanted transmitter), which were then trailed on a day to day basis. Forty per cent of all snakes located had made no movement since the previous day. Average distances, in meters covered per day, were: 142, Pituophis melanoleucus; 51.3, Elaphe obsoleta; 44.7, Crotalus horridus; 28.5, Coluber constrictor; 10, Thamnophis sirtalis; 8, Agkistrodon contortrix; 7, Lampropeltis calligaster; 3.7, Natrix sipedon. Movements were irregular and erratic. For periods of 15-30 days the trailed snakes usually moved progressively farther from their starting points. Three displaced snakes exhibited no homing ability. One female N. sipedon made short, irregular movements typical of resident individuals. A displaced male A. contortrix made an unusually long movement the first night, then settled down to a pattern of short, irregular movements like those of residents. A displaced female C. horridus moved away from the release point but did not travel toward its place of origin approximately 10 km distant.