Burrows and Related Traces in Snow and Vegetation Produced by the Norwegian Lemming (Lemmus lemmus)

Abstract

Lemmings are small, fossorial rodents showing high activity day and night through summer and winter. Although their biology is the subject of many studies, their burrowing activity and burrow architecture have received little attention. In this chapter, the traces of the Norwegian lemming (Lemmus lemmus) produced in snow are described from two mountain sites in the tundra of southern Norway. During the long and harsh winter time, the lemmings build extensive burrow systems along the ground/snow interface and within the snow. These branching and partly anastomosing tunnel networks contain a thick lining of grass and other plant material and thus are well preserved after the snow thaw. Other burrow parts remain unlined or are scattered with fecal pellets. The tunnel networks allowed the lemmings to reach their feeding sites in the surroundings of their dwellings. The burrow systems, which are several square meters in size, contain one or two nests thickly lined with plant material. The nests may contain lemming fur and are built for breeding, nursing, and dwelling. Other parts of the burrow systems are completely filled with rounded and rod-shaped fecal pellets and serve as sites for defecation. They also contain simple rounded, nest-like burrows with the same pellet fill. Lemming burrows in snow are a good example of how those common traces can serve to understand the burrow architecture and the behavior of their producers in habitats which are otherwise difficult to investigate. Beside this neoichnological aspect, rodent burrows in snow may also aid in the interpretation and understanding of fossil vertebrate burrows which remain poorly understood.