Nesting

As we were strolling through the park with friends, we noticed this bird emerging from the hole in the tree and flying away.  I managed to photograph it as it returned to the tree.  The hole, which I assume is being used as a nest, was quite a way up the tree so I wasn't very close; as a result this is a fairly heavy crop, but still reasonably sharp.

Thanks to my fellow blippers for identifying the bird as a nuthatch - a bird I'm not aware of seeing before.