The first day of spring always reminds me that it’s nest box season. It’s time to build and place a few more nest boxes for my favorite birds — the cavity-nesters. This group includes bluebirds, chickadees, titmice, house wrens, tree swallows, screech-owls, kestrels and wood ducks.
Most people love bluebirds, but they nest only in open areas with few scattered trees. Cemeteries, golf courses, and pastures are ideal.
Hang bluebird boxes four to five feet above the ground on a post protected from below by a predator baffle. The baffle could be a piece of large diameter PVC pipe, an inverted sheet metal cone, or a piece of eight-inch stove pipe. The baffle is essential because, without it, a nest box eventually becomes a feeder for raccoons, cats, and rat snakes.
Space nest boxes about 50 to 100 yards apart to minimize territorial squabbles. A bluebird nest is a simple cup of grass or pine needles. Sometimes it’s just a couple inches deep; sometimes it extends up to the entrance hole.
The eggs, typically four or five per clutch, are sky blue (though one in 20 is white) and not quite an inch long. Incubation takes about 14 days. Young bluebirds leave the nest 16 to 21 days after hatching. Bluebirds typically raise two broods and sometimes three, so it’s not unusual to have active nests from April through August.
Advice on building bluebird boxes is often needlessly complicated. A basic box measures four by four inches inside and is 10 to 12 inches high. The entrance hole should measure precisely an inch-and-a-half in diameter and be placed about an inch from the top. This hole size excludes bigger-bodied starlings from using the boxes.
Extend the roof at least three inches beyond the front of the box to protect the entrance from driving rain. The front or side should flip open for easy cleaning.
Though many people don’t have access to bluebird habitat, that doesn’t mean they can’t attract cavity-nesters. Along the edge of the woods, a bluebird box will attract chickadees and titmice. In shrubby old fields and forest edges, wrens are easy to attract. And near ponds in open country, tree swallows abound.
A bluebird box makes a perfect nest box for any of these smaller cavity-nesters. The foundation of a chickadee nest consists of several inches of fresh green moss; the cup is lined with animal fur. A titmouse nest is more a collection of loose dried leaves.
Wrens invariably fill a cavity with twigs before constructing a small cup in a back corner of the box. And tree swallow nests are always lined with feathers — often white feathers from domestic chickens or ducks.
Bigger cavity-nesters require larger nest boxes. A screech-owl/kestrel box has an 8-by-8 inch floor and is 18 inches high. The round entrance hole should be three inches in diameter. Hang a screech-owl box on the edge of the woods. A box for kestrels should be placed in open country — farmland is perfect.
Wood ducks require an even bigger box — 12-by-12-by-24 inches with a 3-by-4-inch oval entrance hole. Ideally, a wood duck box should be placed on a post about three feet above the water. Wood duck boxes can also be hung in trees within sight of a swamp or beaver pond.
Plans for a variety of cavity-nesters can be found at www.ducks.org (search “nest box”). If you’re way ahead of me and already have some nest boxes in place, clean them out soon. Remove old bird nests, and be wary of deer mice nests.
Hazard. Use a stick to remove old nesting material and be careful to not inhale the dust. Cover your mouth and nose with a dust mask. Dust from deer mice nests might contain the hantavirus, the agent of a potentially serious disease. Given this risk, slight though it might be, cleaning nest boxes is a job for adults, not children.
Cavity-nesters began searching for and exploring cavities in January and February, but nest building doesn’t begin until late March or early April. Therefore, now is the perfect time to put up a few nest boxes. Providing nest boxes is as simple as conservation gets, but its impact is profound.
(Send questions and comments to Dr. Scott Shalaway, RD 5, Cameron, WV 26033 or via email at his website, http://scottshalaway.googlepages.com.)