The red tree vole (''Arborimus longicaudus'') is a

rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...

of the

Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though ...

, found in the US states of Oregon and California. They were formerly known as ''Phenacomys longicaudus'' and have also been called the red tree mouse.

Description

The red tree vole is a

in the family

Cricetidae The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, muskrats, and New World rats and mice. At almost 608 species, it is the second-largest family of mammals, and has m ...

. It is found only in coastal forests of Oregon and northern California. They exclusively eat the needles of conifers, primarily

Douglas-fir The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Oregon pine, and Columbian pine. There are three va ...

(''Pseudotsuga menziesii''), though they have occasionally been reported to eat the needles of

Sitka spruce ''Picea sitchensis'', the Sitka spruce, is a large, coniferous, evergreen tree growing to almost tall, with a trunk diameter at breast height that can exceed 5 m (16 ft). It is by far the largest species of spruce and the fifth-larg ...

(''Picea sitchensis''). Red tree voles are about 6-8 in long, including the tail. When they are young, they exhibit a dull brown coat and develop a more reddish color with age. They are nocturnal and very difficult to see, but they can be detected by finding piles or wads of these resin ducts on the ground. Tree-vole-resin-ducts

Nesting and Home Range

Red tree voles live almost exclusively in Douglas-fir trees, though they have occasionally been found in Sitka spruce and

western hemlock ''Tsuga heterophylla'', the western hemlock or western hemlock-spruce, is a species of hemlock native to the west coast of North America, with its northwestern limit on the Kenai Peninsula, Alaska, and its southeastern limit in northern Sonoma ...

(''Tsuga heterophylla''). They sometimes spend their lives in just one tree, and in very large trees with complex structure many generations can live in different parts of the same tree. Red tree voles have been shown to have a home-range averaging around 800 m², though this area is somewhat smaller in old forest (<80 years) and larger in young forest. Within this home-range they can have nests in up to 6 different trees, although 2 nests are average for females and 3 nests are average for males.Swingle James. Daily activity patterns, survival, and movements of red tree voles (Arborimus longicaudus) in western Oregon. When eating Douglas-fir needles, they carefully remove the fine resin ducts (which resemble coarse, straight hairs) along each edge of the needle, which then become a major component of their nests (see image below). As well as these resin ducts, their nests are composed of small Douglas-fir cuttings and their own scat. These nests are often built on or in large or epicormic branches, broken tops, cavities and split trunks, and are always within the live crown.

Reproduction

Both sexes of red tree vole build nests, though the maternal nests are considerably larger. Red tree voles have small litters consisting of 1 to 4 offspring and a long gestation period of 28 days compared to other Microtines. Juveniles depend on their mothers for 47 to 60 days before complete independence. Females exhibit post-partum mating where they can breed within a few days of giving birth and it is common to find two separate litters living in the same nest. During peak breeding periods (winter and spring), males disperse and travel longer distances from home in search for females that are sexually receptive. Females tend to stay closer to their nests, therefore having smaller home ranges.

Predation

The

northern spotted owl The northern spotted owl (''Strix occidentalis caurina'') is one of three spotted owl subspecies. A western North American bird in the family Strigidae, genus '' Strix'', it is a medium-sized dark brown owl native to the Pacific Northwest. An ...

is one of the red tree voles' primary predators. Recent studies show that short tailed weasels are also another primary predator of the red tree vole. Females are easier to detect by predators due to their maternal nests. The time they spend outside of their nests searching for food to bring back for their young also puts them at a higher risk of predation.

Conservation efforts

Their habitats in old forests have become a concern for the species. Logging and

habitat fragmentation Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes ...

has determined their status as vulnerable on the list of sensitive species on the Oregon coast. They are vulnerable to timber harvest due to their arboreal lifestyle and their low reproductive rates contribute to the concern of the species becoming further threatened. They are an important food source for the threatened Northern Spotted Owl and have been listed as a "survey and manage species" under the Northwest Forest Plan (NWFP) in order to help manage the area's ecosystem.

References

{{Taxonbar, from=Q1761767 Arborimus Mammals described in 1890 Taxonomy articles created by Polbot Mammals of Oregon