How does a mouse find its way around in a field — a fairly homogeneous, bland environment with few clues? Simple — it makes its own landmarks, according to Pavel Stopka and David MacDonald from Oxford University, UK. After noticing that wood mice in the wild tended to make piles of objects such as leaves and then return to them frequently, Stopka and MacDonald (writing in BMC Ecology) tested the idea that the piles were artificial landmarks by bringing wood mice into the laboratory.

The researchers placed the mice in an unfamiliar environment and provided them with small white discs — potential landmarks. Sure enough, “The mice tended to collect the white discs, then move them to the more interesting area. The mice would then explore the area in the vicinity ... continually returning to the disc,” (BBC News Online, 29 April 2003). Cordis News (29 April 2003) notes that “These movements seemed to confirm that the mice were using the discs to orient themselves and to mark places of interest.”

Why create these visible road-signs, rather than using scent markers? One explanation, according to the New Scientist (30 April 2003), is that wood mice are “wholly visual ... they have very big eyes.” Alternatively, Cordis News raises the possibility that “The mice may have chosen to use 'signposts' rather than scent marks as they can be moved about and cannot be detected by predators.”