Document Type



It has long been reported that the larval period of Rana catesbeiana in the North lasts for two years (Pope, '47, Wright and Wright, '49, Smith, '50). Examination of tadpoles from such ponds indicates that two age classes are present. The two groups result from the fact that eggs are deposited every year while tadpoles transform only after their second winter. In the light of this information, we were quite surprised to find bullfrog tadpoles apparently of only one age group in Iowa City. 1 In view of this general information, it seems possible that bullfrog tadpoles in this vicinity undergo an abbreviated larval period. Premature metamorphosis of these tadpoles may occur in even more widely distributcd areas since Klimstra (‘47) reports similar observations on Rana catesbeiana from several farm ponds in southern Iowa. In these ponds which were newly· constructed, transforming tadpoles were seen one year after adult bullfrogs first invaded them. Measurements of the tadpoles seemed to fall in one group, ranging in size from 4.1 - 5.9 inches. Unfortunately the number of tadpoles which were measured was not reported. Since all these observations of abbreviated metamorphosis seem to be of such general nature, we decided to follow closely the life history of bullfrog tadpoles in two large ponds on the Rohner farm about five miles south of Iowa City.

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Journal Title

Proceedings of the Iowa Academy of Science





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©1956 Iowa Academy of Science, Inc.



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