Maturational and Seasonal Molts in the Golden Mouse, Ochrotomys nuttalli

Abstract

The adult pelage of the golden mouse ( Ochrotomys nuttalli ) is attained by a single maturational molt. Data on the post-juvenile molt were obtained from 96 young golden mice. This molt began on the ventral surface and spread dorsally, meeting in the dorsal midline. It then proceeded anteriorly and posteriorly. The average age at which male golden mice began molting was 36 days, whereas that of females was 38 days. The average duration of molt for the sexes was 29 days and 25 days, respectively. Golden mice undergo two seasonal molts—spring and fall. Data were obtained from 36 mice. The winter pelage was generally much darker than the summer pelage. Both spring and fall molts were more irregular than the post-juvenile molt, and the spring molt tended to be more irregular than the fall molt. Young golden mice born after 1 October and 8 April appeared to combine the post-juvenile and seasonal molt. Hair replacement was more irregular than during the normal post-juvenile molt.