Birdhouse Building Tips
› Qualities and construction: A bird box should have a sturdy back and be made of inchthick untreated wood (this will end up a little smaller than an inch once planed, Zoller notes). He recesses the base and cuts off its corners so water doesn’t gather inside the house, and ensures the box has vent holes so its residents don’t overheat. Accordingly, inch-thick sides insulate birds against extreme temperatures. “You want a roof that’s angled and that sticks out,” Zoller says. This keeps water from getting in, but also provides protection from predators. Door holes are different sizes for different birds: an inch-and-a-half hole, for instance, allows bluebirds in but is narrow enough to keep more aggressive starlings from entering and pecking the bluebirds. Nuthatch boxes need an inch and a quarter holes. Squirrels can chew up door holes to get into bird boxes, so you may need to add a second block or a metal plate with a hole as well.
Inside and below the hole there should be a “ladder” of grooves so nestlings can climb out.
› No perch necessary: Birds don’t need perches on their houses. These simply give predators easier access, Zoller says.
› Cleaning: Birds are going to use the bathroom in their bird boxes, and these should be cleaned, both for smell and to keep parasites under control. If you pre-drill holes in the side walls and top of the front panel and then attach that panel with galvanized deck screws, you can open the front to clean your bird box. (Wear gloves for cleaning, Zoller recommends, and leave the panel propped open to air out for a few days.)
“A raccoon is smart enough to know how to open it,” Zoller notes, so he drills a hole at an angle and rests a nail in it to lock the panel shut. › Placement and protection: Boxes need to be placed where the birds won’t fry on a hot day or be exposed to predators like cats, raccoons, snakes or other birds. A baffle on the post can keep animals from climbing to the bird box, though pre-made posts like this run at about $60, Zoller says. His budget-friendly homemade solution is a metal fence stake with a baffle made of a 2-inch PVC pipe and cap. A stainless steel bolt centers the pipe.
“We’re not responsible for the birds that are flying around, but we are responsible for the birds we put in a box,” he says. People can also be responsible for birds by keeping their cats indoors, Zoller says.
› What birds need: Bird boxes are not just used for nesting, which is a relatively brief time in the bird’s year. “They’re also used for roosting in the winter when it’s cold,” Zoller says. “They’re warm-blooded animals, so they’ll actually pile in together and share the warmth and that’s their roost.” Birds who use bird boxes are species who typically nest in cavities in dead trees; people tend to cut these down, so bird boxes serve a similar function.