Latitude and Litter Size of the California Ground Squirrel, Spermophilus beecheyi
An inverse relationship between latitude and litter size was found 10 exist in the California ground squirrel (Spermophiltts beecheyi). Correlation analysis of litter size with climatic and physical factors revealed thai the best correlation existed between litter size and the length of the freeze-free period. Ii is hypothesized that the larger litter sizes in southern localities may he a response to heavier predation brought about by an opportunity for more ground squirrel activity outside the burrow at southern latitudes, where the freeze-free period is longer.
Chapman, Joseph A. and Lind, Gordon S.
"Latitude and Litter Size of the California Ground Squirrel, Spermophilus beecheyi,"
Bulletin of the Southern California Academy of Sciences:
Available at: http://scholar.oxy.edu/scas/vol72/iss2/7