5 Tips For Creating Cozy Winter Birdhouses

Learn how to install winter roosts for backyard birds

01-06-2010 // NWF staff

chickadee with gourd
Birds often seek protected places to roost or sleep. Dense vegetation found in thickets or the interior branches of evergreens serve as a windbreak and conceal the birds from night-prowling predators. In winter, a few species of songbirds—the ones that nest in tree cavities or birdhouses in spring—will also use roost boxes to stay warm. Among them: bluebirds, chickadees, titmice, screech owls and some woodpeckers.

Here are five tips for luring them in—and helping them out:

1. There’s not much research on which roost boxes work best, but prefabricated boxes are worth a try. Some look like jumbo nest boxes fitted with interior perches except that the entrance holes are near the bottom of the boxes instead of in the middle or near the top. The idea is that hot air rises, so a low entrance hole keeps warm air from leaking out.

 
Tip: Don’t go with prefab boxes if you want to attract roosting bluebirds. For one thing, bluebirds don’t need the perches because they sleep in a heap on the floor. Bluebird enthusiasts also worry that the low entrance hole creates a draft for floor-sleeping birds and allows predators to reach in and grab a bird.

2. Many people attract roosting birds simply by leaving nest boxes up all winter. Anecdotal evidence suggests roosting birds prefer boxes mounted 10 feet high or more in winter—perhaps because birds feel safer up high.

 
Tip: Nest boxes are usually mounted at eye level, so it’s easy to check on nest progress. Use a telescoping pole to put the box in place and take it down for cleaning and repositioning in spring.

3. Winterize. If you opt for using your spring nest boxes as winter roosting boxes, you may want to block the large ventilation holes—which keep the summer sun from overheating the interior. Foam weatherstripping (the kind sold for air conditioners) works well, and it’s easy to remove when spring rolls around.

Tip: Don’t seal the box up tight. Usually birds like to peek inside a box before entering—possibly to check for danger—and seem reluctant to enter pitch-dark boxes.

4. Try to build  a roost box using plans available on the Internet. Bird enthusiasts recommend a box with a larger-than-usual entrance hole—it’s easier for birds to get a good look inside and also easier to enter and exit.

5. Protect the box from predators. Mount it on a metal pole—cats, raccoons, weasels and rats can climb trees and wooden fenceposts. As heartbreaking as it is to lose a nest box full of chicks to a predator, “it is much more dreadful to think of losing 10 to 20 mature bluebirds in a single winter night,” says Gary Springer, a bird enthusiast who has 35 bluebird boxes on his 50-acre property in Carnesville, Georgia.

 
Adapted from "Providing Birds With Cozy Winter Roosts" by Cynthia Berger, National Wildlife, February/March 2004.

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