competition

House Wren Competition

After our blog about “dealing with predators and problems” appeared last week we received a couple of comments about House Wrens (HW). One comment referred to the HW as a predator. Technically the HW is not a predator but a competitor, and has been known to pierce eggs and even kill baby birds in the nest box. They also have the unique behavior of filling up several available boxes with their nest material with no intention of using those nests. These are known as “dummy nests”. This is an interesting dilemma because the HW is a native songbird and must be treated as such.

House Wren

House Wren

Carolina Wren

Carolina Wren

The House Wren is not a year round species, like the Carolina Wren, and tends to first appear in this area around mid-April. They are fairly common but many of you will never see one in your yard. In 28 years at my home I have never included the House Wren on my “yard bird” list.

House Wren nest is comprised of course sticks.

HW’s use almost exclusively sticks for nest building so when monitoring your nest boxes this is an easily identified nest. Any advice we can offer to help keep HW’s from doing what they do may “backfire”. Offering more choices of nest boxes can alleviate “pressure” on the one or two already present but may encourage more HW activity. Spending a little time monitoring your boxes can help. For instance, if you find sticks in a nest box where Bluebirds have been building a nest you may remove the sticks. Don’t just drop them on the ground because HW’s will just retrieve them and put them back. Or as we suggest with House Sparrows plug the entrance hole to a box for a while if you see HW activity.

Wren guard diagram.

Bluebird using box with wren guard.

An interesting strategy to try if you have experienced HW issues is the wren guard. The wren guard disguises the entrance hole. (Click here for a more in depth look at the wren guard). The wren guard is best used after a Chickadee or Bluebird, for example, have already fully committed to a nest by laying eggs.

It’s good to remember competition among birds for nest sites can reveal some difficult things about nature.

We hope this helps some of you and next week we will spend a little more time on monitoring Bluebird boxes. Please keep the questions coming. We enjoy being able to address things you want to learn about backyard birds.