|Title||Movement and spatial relations of Rana pipiens in spring and summer in northern Michigan|
|Year of Publication||1964|
|Degree||Doctor of Philosophy|
|Number of Pages||288 pp.|
|University||University of Michigan|
|City||Ann Arbor, MI|
The purpose of this study was to determine the nature of the movements and spatial relations of Rana pipiens and the factors controlling them. Movements in two populations in Cheboygan County, Michigan, were studied by means of a trailing device for following individual frogs, by trapping, by weekly censuses of the study areas and by direct observation. In the summers of 1960 and 1961, and the spring and summer of 1962, more than 6000 frogs were marked for individual recognition by toe clipping. Trailing was accomplished by means of a spool of thread, mounted in a holding device on the backs of adult frogs, which unwound as the animals moved, marking their routes. 136 frogs were trailed for a total of 681 frog-days (one frog/one day); individuals were trailed continuously for periods up to 35 days. Budzinski's study area was within a 4.25 hectare pasture containing an abandoned gravel pit and small marsh, both having water much of the summer. The Sedge Point study plot was a 1.2 hectare region surrounding two beach pools on a point of land extending into a lake and bounded on its inland side by a red maple woods. In spring, adult frogs preceded the young out of hibernation. During, and for three to four weeks after breeding, all sizes of Rana pipiens were confined to bodies of water and did not occupy the fields as they did during summer. This seasonal difference in habitat may be the result of seasonal physiological changes, differences in availability of cover or food, or environmental temperature differences. Sometime between May 21 and June 4 in 1962, Leopard Frogs at Budzinski's abandoned the ponds and began moving to their home ranges in outlying regions; a few did not reach their ranges until early July, possibly because a lack of rain in June prevented earlier movement. At Sedge Point 39% were on their home ranges within a week after emergence from hibernation in late April; this was possible because of extensive spring flooding of the area and the fact that over 90% of the resident frogs had ranges adjoining ponds, enabling them to remain in water while on their ranges. In summer, frogs in their second season, or older, limited most of their activities to a home range. At Budzinski's, ranges of second-season frogs were less permanent than those of adults, for most females and many males moved to areas more remote from water upon reaching adulthood; the shift probably occurred early in their third season. At Sedge Point, where the region inhabited by Leopard Frogs was smaller and more confined by unsuitable habitats, second-season ranges were commonly reoccupied. Adults in both study plots tended to reoccupy the same home range year after year; only one adult, a female, was known to have shifted her range within a study area. One male, absent from his range in the second summer of the study, returned to it in the third year; presumably he occupied another range elsewhere in the year he was absent.