I know it seems like this winter will never end, but days are getting longer, and just a few days ago, I finally saw blue sky and felt the warmth of sunshine.
With longer days and bright sunshine comes hope in the form of bird song. And no voices sound better on a cold February day than those of eastern bluebirds, Carolina chickadees, tufted titmice and Carolina wrens.
It will be at least another month before these birds start building nests and another few weeks until they lay eggs, so there’s still time to build a few nest boxes for these cavity-nesting backyard birds. Few backyard projects are more rewarding.
The supply of dead trees and natural cavities limits the number of cavity-nesters that inhabit any area. Providing nest boxes is a simple solution to this nest site shortage.
But only cavity-nesters, not open nesters such as robins and cardinals, use nest boxes or birdhouses. Only cavity-nesters have the strong feet and fearless curiosity required to explore deep, dark nooks and crannies.
The birds that use nest boxes vary with habitat. Eastern bluebirds prefer open country with a few scattered trees. Hay fields, pastures, cemeteries, and golf courses are ideal bluebird habitat, and if there’s a pond or wetland nearby, tree swallows may also use nest boxes in these areas.
If you live in a wooded area, don’t expect bluebirds. Chickadees, titmice, wrens, and maybe even white-breasted nuthatches use nest boxes in more wooded settings.
A simple four-inch by four-inch by 10-inch box with an inch-and-a-half hole is all bluebirds and these other small cavity-nesters require. Build a bigger box (8-inch by 8-inch by 18-inches high with a three inch hole), and you might get an eastern screech-owl or American kestrel.
Any untreated lumber will do, but exterior plywood is relatively inexpensive and ages well. Use stock that’s three-quarters to one inch thick. It insulates nests from spring chills and summer heat.
The actual design and appearance of the box are unimportant to cavity-nesting birds. They simply require a secure site that protects the nest from foul weather and predators.
Here are a few basic tips to keep in mind.
• Assemble with galvanized screws to increase the life of the box.
• It’s not necessary to paint or stain nest boxes, but use light colored earth tones if you do. They absorb less heat and are less conspicuous to vandals.
Put a shingle or several coats of water sealer on the roof; it receives the greatest exposure and weathers faster than the sides. Do not paint the inside of the box.
• Be sure the box can be opened from the front or side for easy monitoring and cleaning. A box that can’t be opened and cleaned is worthless after just one nest.
• Place the top of the entrance hole an inch below the roof. Keeping the hole high makes it more difficult for raccoons and cats to reach in and grab the contents of the nest.
And because raccoons and cats are so common, protect the nest box from below with a metal predator baffle. A good baffle costs $25 to $50, will last a lifetime, and prevents a nest box from becoming a predator feeder. I prefer to have fewer predator-proof boxes than many predator feeders.
• Extend the roof at least five inches over the front of the box to protect the hole from wind-blown rain and marauding paws. Drill four quarter-inch holes in the floor so the box drains well if it does get wet.
• Never put a perch on the outside of a box. Cavity-nesters have strong feet and easily cling to vertical wooden surfaces. A perch only invites house sparrows to use and defend the box.
• Finally, boxes should be in place by mid March. Use plastic coated number 12 or 14 electrical wire to strap boxes to posts. Hang boxes so they will be shaded during hot summer afternoons, and orient the hole to avoid prevailing winds and driving rain.
For more information and detailed nest box plans, visit www.nestwatch.org and click the “Learn” button. Then teach a child about cavity-nesters this spring.