A pregnant fox squirrel feeds on the green catkins and leaves of an oak, pausing several times to rest. Pregnancy is a demanding time for female squirrels. For a litter of three, during the approximately 45 day gestation period (Havera, 1979, p. 963), she will have to produce on average five percent of her body weight in newborn mass (Average Mass: Hayssen, 2008, p. 865; Newborn Mass: Havera, 1979, p. 963). Most squirrels, birthing their first litter in February or March (Steele & Koprowski, p. 108), gather the extra energy and nutrients in time of late winter dearth, but by going so give the young more time after they are weaned to mature before winter comes again.
Havera, S. P. (1979). Energy and nutrient cost of lactation in fox squirrels. The Journal of Wildlife Management, 43:958-956.
Hayssen, V. (2008). Patterns of Body and Tail Length and Body Mass in Sciuridae. Journal of Mammalogy. 89(4):852-873.
Steele, M. A. & Koprowski, J. L. (2001). North American Tree Squirrels. Washington and London: Smithsonian.
Image Date: 2009MAY15
Image Species: Sciurus
(EXIF information is accurate, stamped in UTC time).
Page and Pictures By Hannah Leitheiser