Dung beetles are beetles that feed on feces. Beetles in some species of dung beetles can bury dung 250 times heavier than themselves in one night. Many dung beetles, known as rollers, roll dung into round balls, which are used as a food source or breeding chambers. Others, known as tunnelers, bury the dung wherever they find it. A third group, the dwellers, neither roll nor burrow: they simply live in manure. They are often attracted by the dung collected by burrowing owls. There are dung beetle species of different colours and sizes, and some functional traits such as body mass (or biomass) and leg length can have high levels of variability.