During the summers of 1961, 1962, and 1963, mass emigrations of Rana pipiens pipiens Schreber occurred at the end of the first week in July. The intensity of the movement varied in the three years. Environmental causes for this movement were considered; temperature changes, precipitation or crowding do not seem to be operating. Samples of the tadpole populations were examined and the metamorphic changes prior to emigration are rapid and regular. With final metamorphosis into juvenile frogs, the emigration suddenly begins. It appears to be triggered by internal events related to maturation.
Proceedings of the Iowa Academy of Science
©1964 Iowa Academy of Science, Inc.
Bovbjerg, Richard V. and Bovbjerg, Ann M.
"Summer Emigrations of the Frog Rana Pipiens in Northwestern Iowa,"
Proceedings of the Iowa Academy of Science, 71(1), 511-518.
Available at: https://scholarworks.uni.edu/pias/vol71/iss1/76