Wildlife: Backyard homes for cavity nesters
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Last week, a day after the morning low temperature plunged to 9 degrees, the sky cleared and the thermometer rebounded to 45 degrees. That balmy afternoon, bluebirds, chickadees, titmice and Carolina wrens sang with spring-like enthusiasm. It reminded me to get my nest boxes ready because all four species use boxes within 100 yards of my house.
Though only about 85 of 700 species of North American birds nest in cavities, many of those that do are welcome in backyards. Because natural cavities are a limited resource, the best way to attract cavity nesters is to place nest boxes in suitable habitat. For example, pastures, hay fields, cemeteries and golf courses are ideal for bluebirds. Forest edges attract chickadees and titmice, and Carolina wrens often stay close to homes and sheds.
Cavity-nesters have already begun searching for and exploring cavities, but nest building usually doesn't begin until late March or early April. Hanging nest boxes now makes them a part of the natural landscape so birds are more likely to use them.
Hang nest boxes 4 to 5 feet above the ground on a post protected from below by a predator baffle. The baffle is essential because unprotected nest boxes eventually become raccoon and rat snake feeders.
A basic nest box for cavity-nesting song birds measures 4 or 5 inches square (inside dimensions) and is 10 to 12 inches high. The entrance hole should measure precisely 1 1/2 inches in diameter and be placed about 1 inch from the top. This hole size prevents bigger-bodied starlings from using the boxes. The front or side should flip open for easy cleaning.
For detailed nest box plans for a variety of species, visit www.birds.cornell.edu/nestinginfo/nestboxref/construct. If you lack tools and a workshop, look for nest boxes at wild bird stores, nature centers or the Pennsylvania Game Commission. The agency's boxes are surprisingly affordable; a set of two bluebird boxes costs just $30, delivered. The PGC also sells nest boxes for kestrels, screech owls, wood ducks, mergansers, squirrels and bats. To order, call 814-355-4434 or visit www.pgc.state.pa.us and click on "Howard Nursery" from the "General Store" drop down menu and then select "Wildlife Homes Order Form."
First Published February 24, 2013 12:00 am