Early summer reproductive hiatus in wild adult white-footed mice

An early summer breeding hiatus in wild populations of white-footed mice (Peromyscus leucopus noveboracensis) in eastern Virginia has been well documented. This report explores the question of the age of the reproductively inhibited animals and demonstrates that mice reproductively suppressed during the hiatus period were not merely young-of-the-year who had not reached sexual maturity but were adults, many of which were known to be reproductive before the hiatus period. Further, animals known to be adults for an average of >2 months when necropsied during the hiatus period had significantly smaller testes, seminal vesicles, and ovaries than adults with similar histories, captured, and necropsied during other reproductive periods of the year.