secondary hole-nesters
Re-use
Many species living in tree holes cannot excavate their own quarters. They are dependent on others' holes to live in and are called "secondary hole-nesters". An old black woodpecker's hole is attractive to the pygmy owl, jackdaw, hawk owl, golden eye, squirrel and bats.
Why not a box?
Many secondary hole-nesters live in nesting boxes just as well as natural cavities. The best examples are found in your garden: pied flycatcher, starling, great tit and blue tit.
