Tit box entrance deliberately enlarged but no sign of a nest

[Milooshea]

We have a small nest box on in a shady position on an north east-facing fence. It is not of a very good design, being rather shallow. However, the hole was the standard blue tit size. We've just noticed that the bottom of the hole has been enlarged significantly, requiring considerable effort, but the box doesn't seem to have been occupied. Anybody have any ideas which bird or beast might be responsible? Great Tit? Nuthatch? GS Woodpecker?

Milo

[Buenchico]

See boxes 22 and 24 here, for a couple of possibilities:
http://www.cock-road-...ird-box-survey-06.htm

Chris

[ladybirder]

Milo I watched over several days last year while a Blue Tit enlarged the hole of the nesting box in our garden. Only when it was satisfied did it and its mate nest and raise a family.

[pusskin]

we'd go for a woodpecker milooshea.
some boxes have metal around the hole, to stop woodpeckers making the hole bigger so they can get inside

[wildwood]

Maybe it is one of those feral Ringneck parrot.