Abstract from: Thompson, R. L. 1996. Home range and habitat use of western red-backed voles in mature coniferous forests in the Oregon Cascades. M. S. Thesis. Oregon State University, Corvallis, OR. 88 pp.

Short rotations associated with forest management practices in the Pacific Northwest may reduce the abundance of habitat features within home ranges of western red-backed voles (Clethrionomys californicus). I studied western red-backed voles and attempted to define habitat use to provide data that could be used to guide management of this species. I described home ranges and movements of western red-backed voles in 3 mature Douglas-fir stands in the southern Oregon Cascades. Red-backed voles were radio-collared in August and September 1994 (n = 12) and in July and August 1995 (n = 11). Telemetry locations were recorded hourly during the vole's active periods (dusk to dawn). I used the adaptive kernel method to estimate size of home ranges and core areas. Average sizes of home ranges were 0.13 ha for females (range 0.03 - 0.23 ha) and 0.74 ha for males (range 0.52 - 0.96 ha). Size of core areas averaged 0.02 ha for females (range 0.003 - 0.04 ha) and 0.17 ha for males (range 0.09 - 0.34 ha). Movements between successive telemetry locations averaged 12 m for females (range 5 - 19 m) and 30 m for males (range 24 - 43 m). Females exhibited bimodal patterns of activity, whereas males were active all evening.

Radio-telemetry and pitfall trapping were used to identify habitat used by western red-backed voles. Of the home ranges estimated in 1994, vegetative components and habitat features were measured within vole core areas and compared to measurements taken randomly in the remainder of the home ranges. Associations of vole abundance with coarse woody debris volume and organic soil depth were estimated in six mature Douglas-fir stands. There were no consistent relationships detected between red-backed vole abundance and volume of coarse woody debris at a stand or trap station level. Home range core areas were characterized by deep organic soil layers and large volumes of decayed logs. Deeper organic soil and greater volume of medium diameter, decayed logs distinguished core areas from randomly selected areas of the home range. Because of the biases and assumptions associated with the trapping data, the telemetry-based habitat associations in my study are stronger than those based on capture data. Nest sites of six adult females were located within or under decaying logs. Nest material consisted of moss, bark pieces, and lichen. Silvicultural prescriptions in coniferous forest stands that provide deep organic layers and high down log volumes should be conducted when managing future populations of western red-backed voles.