Distribution and Abundance of Tree Voles in the Northern Coast Ranges of Oregon

Abstract

We sampled 86 randomly selected survey plots to evaluate the distribution and abundance of Red Tree Voles (Arborimus longicaudus) on the Tillamook and Clatsop State Forests in the northern Coast Ranges of Oregon in 2011-2013. We conducted surveys by visually searching for tree vole nests while walking along 500 m of transect in each plot. Trees with potential nest structures were climbed to determine if the structures were tree vole nests. We found tree vole nests in only 4 random plots, all of which were located near the coast, at the western edge of the Tillamook State Forest. Of 33 tree vole nests located, 20 (61%) were in old forests ($80 y old), and 13 (39%) were in 1 plot in a young forest that was 65 y old. We concluded that tree voles were absent from most of the Tillamook and Clatsop State Forests, probably due to the fact that most of the area was either logged or burned in the early 1900s, and subsequently intensively managed on short rotations. We also suggest that remnant stands of old forest on Bureau of Land Management and state lands are acting as source populations from which tree voles populate adjacent young forests. Cuttings found in nests provided evidence that most of the voles were feeding on needles of Western Hemlock (Tsuga heterophylla) or Sitka Spruce (Picea sitchensis).

Tree voles: an evaluation of their distribution and habitat relationships based on recent and historical studies, habitat models, and vegetation change

“…Based on the data from all sources examined, we concluded that tree voles in Ranges and northern Cascades, where they are mostly restricted to isolated populations in remnant stands of old forest on federal and state lands (Forsman et al 2008Price et al 2015). The fact that tree voles still occur in some local areas in the northern Coast Ranges and northern Cascades suggests that the species probably occurred in old forests throughout this region prior to the arrival of European settlers in the early 1800s.…”

“…During 1990-2013, we conducted a variety of field and laboratory studies on tree voles, including studies of home range and survival (Swingle andForsman 2009, Swingle et al 2010), distribution (Forsman et al 2004(Forsman et al , 2009aPrice et al 2015), behavior (Forsman et al 2009b), water consumption (Forsman and Price 2011), sampling methods (Swingle et al 2004), and genetic relationships (Bellinger et al 2005. During these studies we searched for tree voles at many locations in Oregon and California, including 44 surveys in which we attempted to determine if tree voles were still present in areas where they were found by earlier researchers (retrospective surveys).…”

“…Particularly noticeable was the absence of red tree vole detections in the northern Coast Ranges (Price et al 2015) in the extensive areas that burned during the Tillamook Burn fires of 1933-1951 (Holbrook 1943, Kemp 1967, Lucia 1983, Wells 1999, and the 1902 Columbia and 1865 Silverton fires in the north Cascades ( fig. 1-6).…”

Nest trees of northern spotted owls (Strix occidentalis caurina) in Washington and Oregon, USA

“…These infections benefit a wide range of wildlife species’ habitat and are used for roosting, foraging, food caching, and nesting by small mammals, (e.g., Arborimus spp., Tamiasciurus spp., Tamias spp., Glaucomys spp., and Neotoma spp. ), many small birds, and other owl species [ 49 – 52 ]; including cavity nests resulting from infected decadent trees [ 53 ]. These mistletoe infections appear to be absent or uncommon in coastal mountain ranges in Oregon and Washington, suggesting availability of these structures is the primary driver in use for nesting by NSOs.…”

Patterns of red tree vole distribution and habitat suitability: implications for surveys and conservation planning

“…), or patterns of timber harvest and wildfire (Price et al. ) or other human uses. The spatial variation of tree vole occurrence throughout their range likely represents many of these factors.…”