House Wrens can be found singing everywhere in the woods during Spring and Summer. While they flit about in bushes and thickets and are quite territorial, they often find interesting places to nest. I was following a couple of wrens moving about incessantly and noticed one of them disappear into a huge hole in a tree trunk. I waited patiently for quite some time and was rewarded with this series of photos below. I went to the same spot a few days later and sure enough was greeted by a singing wren.