BACHMAN,G.C.: Changes in leukocyte counts in hibernators from spring through summer.

At high elevations, hibernators such as Belding’s ground squirrels (Spermophilus beldingi) emerge through snow and are unable to forage for the first few weeks of spring. Potentially, these individuals face a trade-off between allocating limited energy and nutrients to re-establishing physiological function, and the need to fuel activity associated with the brief breeding period which also occurs at this time. Immune function appears to be among the systems that show some degree of regeneration after emergence. Blood smears were collected periodically from squirrels from May (days after emergence) through August allowing me to follow changes in individual profiles over time. Two measures were taken from these slides – a differential leukocyte count and a measure of the relative number of leukocytes relative to erythrocytes. The analyses focus on the populations of immature and mature neutrophils, lymphocytes, and immature leukocytes as other cell types were rare. The time series indicate a progressive maturation of the leukocyte population and an increase in the relative number of leukocytes. Associations between leukocyte counts and individual behavior and body composition will also be presented.