The soft leaves of oaks breakdown with ease in autumn, forming a rich leaf-mould beneath the tree, supporting invertebrates such as the stag beetle and numerous fungi like the oakbug milkcap. Holes and crevices in the tree bark are perfect nesting spots for the pied flycatcher and the marsh tit. Several bat species also roost in old woodpecker holes or under loose bark and feed on the rich supply of insects in the tree canopy.