April 2018 Nuthatch nest building

I find the Nuthatch's nest building behaviour fascinating.  They take a larger hole and build mud around the entrance to reduce it to the required size.  The mud sets and prevents larger egg thieves from entering.  This pair seems to have selected quite a large hole and it will require quite some effort.

Nuthatch filling the entrance with mud

 I will go back in a few days and try to get an image of their workmanship.