This spring I put up a bluebird house in our backyard, hoping that Bluebirds would come and set up their nest inside. However, Chickadees took possession of it first, then Sparrows tried to invade. Finally a couple of House Wrens evicted all the other occupants and settled in. They are small birds but very feisty and aggressive.
The House Wren in the above photo was holding a fecal sac that it would take and deposit somewhere away from the nest. It could also take similar looking spider egg sacs to deposit inside the nest. When the spiders hatch, they will help the nest by eating parasites in it.
Unlike other backyard birds, House Wrens eat insects and don’t care for the sunflower seeds in our feeder.