VALIDATION TESTS OF AN AMPHIBIAN CALL COUNT SURVEY TECHNIQUE IN ONTARIO, CANADA

Amphibian call count surveys in Ontario use a common survey protocol. We evaluated the precision and accuracy of data collected by these met hods. Multiple observers monitored the same routes to determine inter- observer variation. Inter-observer agreement in evaluation of calling intensity and occurrence was generally high, and the experience of the observer affected estimation of both calling intensity and the number of individuals calling. There was no significant increase in inter-ob server agreement in evaluation of calling intensity or occurrence with 5-min versus 5-min surveys. Longer surveys rarely resulted in the ide ntification of species not heard in the first 3 min. Surveys of 30-60 min duration indicated that return for effort declined sharply during the second minute of the survey, although new species were sometimes h eard after as long as 15 min. Simultaneous intensive and extensive mon itoring was performed on populations of Fowler's toads (Bufo fowleri) in southern Ontario and bullfrogs (Rana catesbeiana) in central Ontari o to determine whether there was a relationship between calling intens ity and chorus size or population size. We found a linear relationship between call counts and chorus size in both species. We conclude that the data generated with the call count surveys were adequately precis e, but accuracy remains to be validated. Further investigation of the relationships among population size, chorus size, calling intensity, a nd environmental factors are required to determine whether extensive m onitoring of calling amphibians can be used as an index of actual popu lation size. However, until that time, we recommend that calling amphi bian surveys be used as the first part of an integrated program using extensive monitoring to identify areas where populations may be declin ing, and intensive monitoring to confirm or refute reports of declines .