Birch Polypore

Obligate on Silver Birch, virtually never recorded on any other host. Causes a brown rot that softens the trunk; infected birches are preferentially selected by Great Spotted Woodpecker for nest excavation.

Preferentially excavates Birch Polypore-infected Birch trunks, where the brown rot created by Fomitopsis betulina softens the wood sufficiently for cavity creation. A documented three-way chain: Birch → Birch Polypore → Woodpecker.

Feeds on invertebrates in birch polypore fruiting bodies and relies on polypore-softened wood for cavity excavation (Wiktander et al. 2001).