What if house wrens pose a constant problem by building nests in bluebird boxes?
Bluebirds usually start their nesting activities two to three weeks before house wrens begin theirs. This give the bluebirds some advantage in locating nesting sites. Once the house wrens arrive in their nesting territories, they will sometimes enter a bluebird nest box, puncture bluebird eggs and may even eject the eggs from the nest. They have been know to remove nestlings from the box as well and simply drop them to the ground. To minimize house wren competition, locate the nest box in open areas, as far as possible from stands of trees, shrubs, and other underbrush. Although it is unlawful to remove a completed House Wren nest, you may remove the male wren’s uncompleted or dummy nest.
