Because they readily accept almost any type of pre-existing cavity as a shelter for their nests, they will use a birdhouse if you provide one. In fact, since female wrens are a little fussy, you might provide several houses from which she can choose. Hang a wren house from a tree limb five to ten feet from the ground and watch for tenants. To see some examples go to Yardener’s Tool Shed for Houses Designed for Wrens
Houses should be about 4 inches square at the base and 8 inches high. The entrance hole must be no larger than 1 1/4 inches in diameter, centered about 6 inches above the floor of the box . Eliminate the perch to discourage predator birds. Wrens will reuse old nests for the second brood and even the following season.
In the North wrens typically lay eggs from the middle of May to the end of July. In more southern areas nesting begins 2 to 4 weeks earlier. They use twigs, grass, moss, feathers and cotton nesting materials. Both parents build the nest, then the female incubates the four to six eggs for 13 to 15 days. The male helps raise the brood but fades from the picture once the task is done for the year. They have two broods per season, three if the wrens do not migrate. Wrens have a lifespan of 5 to 7 years.