Small mammal populations occurring in a diversified winter wheat cropping system

Some Triticum aestivum (winter wheat) growers in the western region of the Northern Great Plains, USA, use a 3-year rotational, diversified dryland cropping system consisting of alternating strips of T. aestivum, fallow, and an additional spring sown crop such as Avena sativa (oats) or Zea mays (corn). Small mammal population characteristics (species richness, abundance, diversity) of the crops associated with this cropping system are unknown. Small mammal populations and vegetation characteristics (habitat) were evaluated at two sites in June 1998 and 1999 in three crops of the rotation and on undisturbed Conservation Reserve Program (CRP) grasslands. Small mammal abundance and diversity were highest in T. aestivum and grassland at both sites each year. Peromyscus maniculatus (deer mouse) was the most abundant species. Percent vegetation cover was significantly higher in T. aestivum and grassland, respectively, at both sites each year. Regression analyses using pooled data indicated a significant relationship between percent vegetation cover and small mammal species richness, abundance, and diversity. T. aestivum provided valuable habitat for small mammals in winter, spring, and early summer. Alternate grain crops in the diversified cropping system, which is absent in traditional 2-year systems, probably offered additional valuable protective cover for small mammals following T. aestivum harvest.