Daniels, J.M. 1981. An inventory of Microtus chrotorrhinus in northeastern Minnesota. Final report submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 10 pp.
Trapping in Cook County during 1980 and 1981 has led to the discovery of five new Microtus chrotorrhinus colonies, increasing the number of rock vole populations reported in Minnesota to eight. It is anticipated that additional populations exist in Cook County and, based on similarities in glacial geology, also in northern Lake and St. Louis counties.
The habitat of the recently discovered populations is similar to that reported by previous investigators. It is characterized by a partially open canopy of primarily spruce and fir, with a sparse to dense vegetational layer and a thick, moss and lichen ground cover. At all sites investigated by the contractor in 1980-1981, boulders represented an important component of the landscape. High relative humidities (measure in 1980) and evidence of standing or running water was observed at all sites.
Evidence of disturbance by fire and from logging was noted at the sites investigated in 1981. It has been suggested that rock voles occur in higher densities when trapped in disturbed areas, than in mature forests. This may be an important consideration in terms of management of habitat for rock voles.