A total of 11,307 Australorbis glabratus was marked and released at various points in a 2,700-foot length of the upper end of a stream, Quebrada Blasina, in Puerto Rico. A. glabratus moved an average distance 6 feet both upstream and downstream in the first 24 hours. By the second week the average distances the snails had moved from the release points were 19 feet upstream and 23 feet downstream. After the second week the snails remained in the same general distribution for the ensuing 5 weeks.
A. glabratus are found in colonies in more or less specific locations in a stream. Observations indicated A. glabratus are transported from one water body to another by flood waters or by the adherence of eggs or young snails to the legs of water fowl or animals fording streams. Insects were collected with snails attached to them, and might be responsible for transporting snails from one body of water to another.
Present address: Department of Entomology and Limnology, Cornell University, Ithaca, New York.
Present address: Florida State Board of Health, Jacksonville, Florida.