Does anything eat processional caterpillars?

Blue tit with tasty caterpillar (original photo)

We are all now familiar with the threat posed by these caterpillars which descend from their fluffy nests in the fir trees and form their lengthy trains across the ground. Dogs and cats which investigate them risk fatal stings and any person unwary enough to disturb them will find that the tiny barbs they expel are extremely irritating.
As with many natural threats a solution which can reduce the threat exists in nature itself: blue, great, longtail and other tits (as well as some bats) will attack the caterpillars with impunity.
Some communes in the Lot department which have a surfeit of fir trees have encouraged residents to install nesting boxes for tits and bats in a effort to minimise the threat.
It may be a bit late now for this year as many of the tits around our house are busy feeding young in holes in the walls and trees but worth thinking about for the future.