Circannual cycles of molt in ground squirrels

Abstract
Molt was studied in thirteen-lined ground squirrels (Spermophilus tridecemlineatus) from Kansas and Michigan. In constant laboratory conditions molt showed circannual cycles and generally occurred during the weight gain phase of the circannual body weight cycle. Molt in the Kansas ground squirrels began at a slightly later phase of the body weight cycle and ended at an earlier phase of the body weight cycle than in the Michigan ground squirrels. The relative portions of the body weight cycle spent molting was close to 35% in both populations. Molt is not dependent on the circannual body weight cycle, but is under control of the same circannual system.