House Wren dismantling a chickadee nest

In mid-march Carolina Chickadees built a nest in our nest box. The nest was abandoned due to harassment from House Sparrows. Yestreday the first House Wren of the season showed up and it did not take him long to inpect the nest box! House Wrens are naturally aggressive, and since they use twigs to build their nests, he began to dismantle the soft moss and hair nest the chickadees had constructed, and lay claim to the box!