Singing vole
In the east, they reach as far as the Mackenzie Mountains, being found throughout the Yukon, aside from the northern coasts, and in border regions of the neighboring provinces.They avoid the most extreme environments within these regions, preferring open, well-drained slopes and rock flats with abundant shrubs and sedges.They make runways through the surface growth, connecting feeding grounds to burrow entrances, although these are not as clear as those made by some other vole species.These passages, typically around 2.5 centimetres (0.98 in) wide, make it difficult for any animal larger than a vole to pass through, and thus help protect against predators such as weasels.The voles begin to construct the stacks around August, and by the winter, they may have reached considerable size, with piles of up to 50 centimetres (20 in) in height having been reported.During the Ice Ages of the late Pleistocene, singing voles may have been much more widely distributed than today, and fossils have been reported from as far south as Iowa, which was then probably similar in climate to present-day Alaska.