The bluebirds moved away so I cleaned out the ne3sting box. For 3 days the box was empty but last Friday there were two sticks in the box. We watched as the wren brought sticks to the box and once the wren forgot to turn the stick and struck the box with enough force that it knocked it's self to the ground. Saturday night there were sticks poking out the hole in front of the box. I opened the box and it's full of sticks from top to bottom. What a difference the wren and bluebirds have in nesting materials and size of nests.