who are understandably         distressed when house wrens destroy a family they’ve been watching. House wrens are a protected species, so it is illegal to harm them or destroy their nests. Some people leave alone active nests, but remove sticks from a hollow that does not yet contain eggs. 

      Some bluebirders have better success by allowing house wrens to nest undisturbed. Interesting, male house wrens peck other birds’ eggs and nestlings only until they secure a mate. Female house wrens stop destruction as soon as they lay their own first eggs.

      After a pair of house wrens has started a family and is no longer harming the nests of other birds, the person monitoring a bluebird trail can remove unused dummy nests without pitching the house wrens back into the destructive phase of their breeding cycle.

- Diane Cooledge Porter,

Bird Watcher’s Digest

Tiny and energetic, the house wren is one of the most familiar backyard birds of North America. Because Troglodytes aedons are charming and easy to attract, enormous numbers of nest boxes go up for them (like the one pictured on this page in Lloyd Grotjan’s photograph).

      Not everyone thinks it’s a good idea to offer so much assistance to this species. House wrens sometimes enter birdhouses and natural cavities where other birds are nesting and pierce the eggs or peck and kill nestlings.

      Birds who suffer such attacks from house wrens include members of their own species as well as other cavity nester such as bluebirds, tree swallows and prothonotary warblers.

      Both male and female wrens push eggs out of open nests or plunge their needlelike bills into eggs and nestlings. They don’t eat the eggs they peck, but carry out the shells after they break the eggs. Some researchers theorize that wrens are following an instinctive pattern of cleaning out a potential nest for their own use. Others feel a likely explanation is that wrens destroy other birds’ offspring to reduce competition for food resources they need to raise their own young.

      This behavior presents a conundrum to bluebirders,