Jannett, F.J. Jr. 1990. Habitat breadth population stability and structure of the rock vole, Microtus chrotorrhinus, in northeastern Minnesota. Report submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 23 pp.
The objectives of this study were to: 1) to determine the presence of rock voles on sites where they were and were not trapped in 1982-1989, 2) to determine the numbers of rock voles which could be secured in four-day samples as opposed to the two-day samples undertaken in previous years, 3) to monitor sites where reproductively active female rock voles were trapped as well as some where they were not trapped in previous years, 4) to determine basic aspects of rock vole social structure, and 5) to attempt censuses on some sites. Boulder fields of various sizes in Cook County, Minnesota, on which rock voles were trapped in 1982 and annually from 1983 through 1989, and eskers on which rock voles were trapped 1984-1989, were resampled in 1990 to ascertain if rock voles were still present. Rock voles were taken at 13 of the 18 sites. None were taken at the other 5, despite the increased trapping effort in 1990. This was the first year since 1982 trapping by Christian (1982) in which rock voles were not secured at some sites.