The red tree vole (Arborimus longicaudus) is a rodent of the Pacific Northwest, found in the US states of Oregon and California.

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.

[9] Red tree voles have small litters consisting of 1 to 4 offspring and a long gestation period of 28 days compared to other Microtines.

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.

[10] During peak breeding periods (winter and spring), males disperse and travel longer distances from home in search for females that are sexually receptive.

[12] 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.