House Wrens were in great number (209 nests) again this year – twice the number (105) of House Sparrows. They are protected by wildlife legislation so we can’t take aggressive measures. The best prevention is to place our boxes well away from trees and shrubs. I had one box where a wren pierced all 6 MOBL eggs and pushed them out of the box before filling it with twigs. I actually observed the normally passive MOBL pair later chasing the wren when he tried to take over another nearby box, which the Bluebirds were using as a replacement nest. Aggressive Bluebirds! What’s next?
Diane Leonhardt observed: Wrens seemed to be more aggressive this year… they destroyed several nests on our other trails.