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Full-Text Articles in Animal Sciences
Comparative Life Histories Of Georgia And Virginia Cotton Rats, Bradley J. Bergstrom, Robert K. Rose
Comparative Life Histories Of Georgia And Virginia Cotton Rats, Bradley J. Bergstrom, Robert K. Rose
Biological Sciences Faculty Publications
Adult hispid cotton rats (Sigmodon hispidus) were collected from the field monthly for >2 years from populations near the northern edge of their range in Virginia and contemporaneously from south-central Georgia. Body measurements and weights were taken at capture, and after dissection embryos, corpora lutea, and placental scars were counted and measured; testes and seminal vesicles were dissected out, measured, and weighed. This allowed comparison of several life-history parameters between the populations and tests of several life-history hypotheses. The breeding season was up to 2 months longer in Georgia than in Virginia, where there was typically a 3-month …
The Reproductive Cycle Of Microtus Ochrogaster In Eastern Kansas, Robert K. Rose, Michael S. Gaines
The Reproductive Cycle Of Microtus Ochrogaster In Eastern Kansas, Robert K. Rose, Michael S. Gaines
Biological Sciences Faculty Publications
About 800 Microtus ochrogaster were live—trapped at biweekly intervals from May 1971 through March 1973 in 3 grassland study areas in eastern Kansas, USA. Details of reproduction were determined by autopsy. Population density increased through the first winter, reached a peak in April 1972, then declined sharply during that summer and beyond. Body length, but not body mass, tended to be positively related to density. Both sexes matured at about the same weight; development was somewhat prolonged during the winter months, especially in the winter preceding the population peak. Pregnancy rates were high, approaching maximal iteroparity, throughout the study, with …