Invite bluebirds with proper habitats

Published 2:12 pm Monday, March 11, 2019

Getting your Trinity Audio player ready...

Joni Carlson

I don’t know if it is the “Turalee” call, happy chatter or a brilliant flash of blue that makes me pause, but there isn’t anything better than seeing and hearing an Eastern Bluebird (Sialia sialis) or even better, a pair! I greet them back with, “Bluebird, bluebird, bluebird!” We have learned to show our appreciation for one another in more intimate ways thank just a quick hello.

Providing a great habitat, a predator-protected nesting box and access to water are key on my part — that certainly draws them to my yard. Live mealworms? Certainly, a bonus but not necessary, and it seems to build trust during our spring and summer romance. They have had population declines in the past, but careful monitoring and correct mounting of nest boxes have shown that bluebirds are making a strong comeback.

Now is the perfect time to start thinking of the bluebird season. Do I buy a box or build one? What materials do I need? How far apart should I space the boxes? Are there times I shouldn’t interfere with a nesting box? How can I keep that raccoon or black snake out of my box? Do I clean the nest between broods? How can the community be involved in establishing and monitoring a bluebird trail? All great questions.

Understanding critters in their natural world means educating yourself on their behavior. Once you know the simple facts of their lifecycle, you will gain confidence in the elements needed to help attract them to your yard.

Eastern bluebirds are year-round native birds who breed east of the Rockies from southeastern Canada south to the Gulf of Mexico and stay in the southern regions during winters. They build their nests in natural cavities or in nest boxes or other artificial refuges. Males begin scoping out nests at the end of February and into March. The female starts building the nest usually in the first part of April (takes 3-4 days) preferring shed pine needles almost exclusively for nest.

One egg is typically laid per day after the nest is complete (she makes a cup shape with her bottom to receive the eggs). First nest of the season usually yields five eggs — blue in color and 0.9 inches in size, and the pair can have up to three clutches in a nesting season. Females sit on eggs for 12-14 days with babies all hatching on the same day. The chicks grow quickly eating spiders, grubs and worms both parents are providing. Babies fledge 18-21 days after hatching. The nest box should be completely cleaned out with a brush for the female to build the next nest sometimes as early as five days. The male tends to feed the fledglings for two weeks, and then returns to guard new nest.

You can spot eastern bluebirds in the wild in old woodpecker holes of oaks or dead pine trees, or you can build a house that simulates that cavity environment using wood (we use cedar for our nest boxes) or dried garden gourds with a good placement of a 1.5” access hole.

I have found that bluebirds like to nest and lay eggs in “birdhouse” gourds, but predation (those black snakes and racoons) is hard to control if not properly mounted with baffles and guards. The “Carl Little” bluebird houses we have built following the Virginia Bluebird Society guidelines ( are easy to follow and give great results. Don’t forget to mount nest boxes correctly with predator guards (baffle for snake and Noll guard — hardwire around entry hole to keep cats and raccoons in check).

Keep in mind that other cavity nesting birds like Carolina Chickadees (Poecile carolinensis) and House Wrens (Trogloytes aedon) may adopt your house so know the materials they like to use. Chickadees use moss bottoms and animal fur nesting cups, and house wrens tend to twig it to the top, so you can identify the species and enjoy their lifecycle up close. “Nest and Eggs of North American Backyard Birds” from the NestWatch Project at the Cornell Lab of Ornithology is a great field guide that will build your skills in this.

One problem bird that trail watchers try to deter is the non-native House Sparrow (Passer domesticticus). They are an aggressive species and will kill bluebirds to steal their nesting box. And bluebirds need their space. Make sure to have close to 300 feet of space between the boxes on your property or trail. Open field spaces with some tree or bush edging is ideal for gleaning food and providing protection for fledging birds.


JONI CARLSON is Virginia Master Naturalist with the Historic Rivers Chapter.