Mysterious wormhole?

Mysterious wormhole?

Observation - Mysterious wormhole?. Description: I've been examining these strangely large 'worm holes' in our garden - a large 11-acre wild garden in Cornwall. But yesterday I noticed a large green woodpecker with red brow mining the ground very specifically in some places. I'm wondering whether these

I've been examining these strangely large 'worm holes' in our garden - a large 11-acre wild garden in Cornwall. But yesterday I noticed a large green woodpecker with red brow mining the ground very specifically in some places. I'm wondering whether these holes are caused by him? Or are they a worm? Note dropping found 6in from hole, on second picture - might be relevant.