House Sparrows. ... The male sparrow is particularly nasty and will often kill not just the young bluebirds but even the adults and eggs too. House Sparrows MUST be controlled in the habitat your nest boxes are placed in to ensure the nesting success of bluebirds.

How do I protect my bluebirds from sparrows?

There are several ways to discourage them from using nest boxes, ranging from boxes specifically designed to dissuade sparrows to traps to eliminate them. Monitor nest boxes every day. If you see evidence of house sparrows, discard their materials. Bluebirds make nests of fine grasses, woven together in a tidy cup.

What birds destroy bluebird nests?

Unfortunately for nesting birds here in mid-TN there are a number of predators and pests that can deter, disrupt, or destroy an attempt to nest. It's no different for Bluebirds. The most common problems are the House Sparrow, Raccoons, and Rat snakes.