What is it for....?

I have been watching 'No Merlin!' for the last couple of days and notcied the appearance of these things in the garden.



At first I thought she was tunneling for freedom. Now I have spotted two others appearing. This makes three holes of three different sizes.

I have also been watching 'No Merlin!' following the pants cats around quite a lot. There are three of those. In three different sizes....

Curiouser, and curiouser.....