Something Wild hosts Dave Anderson, of the Forest Society, and Grace McCulloch, of NH Audubon, both admit that the Eastern bluebird is their favorite songbird. With nesting season just around the corner, the Something Wild team has some advice for hosting bluebirds in a nest box.
“Having a pair in your nesting box is amazing to watch,” McCulloch said. “After the eggs hatch, the adults are constantly flying back and forth with food like caterpillars and grasshoppers, bringing meal after meal to those hungry chicks.”
Bluebirds can be picky. Historically, they nested in tree cavities. As those natural nesting spots disappeared, along with added pressures from habitat loss, pesticides and competition from non-native species, Eastern bluebirds declined.
Putting up a box requires some effort, and don’t be discouraged if you put up a nest box and find nothing moves in.
The box itself matters. Bluebirds require a particular entrance hole size. Cornell Lab of Ornithology recommends up to 2 ¼ inches, so it's important to use a design specifically made for bluebirds. Project Nestwatch has a great plan online to build your own.
Bluebird boxes should be placed in open areas like fields, orchards and parks where birds have a wide view and can easily spot insects. Mount them on a pole four to six feet above the ground and face the entrance east to avoid harsh weather.
And if you’re putting up more than one nest box, give them some space. Bluebirds are territorial, so boxes should generally be spaced about 300 feet apart.
You can also help the parents out by providing food. Bluebirds feed their chicks almost entirely insects. “I added a dried mealworm tray feeder to my bird feeder array just for bluebirds this winter,” Anderson said.
A bird bath can provide water for busy parents feeding young later in spring.
Planting native plants in your yard can make a big difference. Planting native plants isn’t just about pollinators, it's good for songbirds as well because native plants support far more caterpillars and other insects than many ornamental plants.
Don’t worry if they don’t immediately take up residence. It can take time for bluebirds to find your box, even a couple of years in some cases.
And of course, other birds can benefit from bluebird boxes. At N.H. Audubon’s Massabesic Center, volunteers have been running an annual NestWatch monitoring program since 1999. They have had species from Tree swallows to Black-capped chickadees using their nest boxes.
House sparrows compete with bluebirds
Another challenge that bluebird landlords sometimes face is the House sparrow, another reason for the decline of Eastern bluebirds. House sparrows were introduced from Europe in the 1800s. They aggressively compete for tree cavities and nest boxes and sometimes destroy eggs, kill chicks, and even can attack adult birds.
Don’t get a nest box with a perch; they attract sparrows.
It also helps to not feed birds in the summer. That’s recommended for many reasons, but it also means a steady food supply isn’t attracting House sparrows and they may move on.
If sparrows keep taking over a box, sometimes the best solution is to move it or even plug the entrance hole for the season and try again next year. Male sparrows can be extremely territorial and fierce when guarding a box in their territory.
If you are lucky, you might see the same bluebird pair raise two families in one summer, one after the other, and suddenly, your backyard becomes a little wildlife refuge.
Something Wild is a partnership between NH Audubon, the Forest Society, and NHPR.
