Bluebirds are Back!

Bluebird entering box

Welcome back the bluebirds with a nest box on your property. Here are some pointers for correct placement of your box:

  • Ideally the box should be installed by mid-February, but you can still install one throughout the month of March and as late as early April when breeding begins. Because bluebirds begin their seasonal movements in February and male bluebirds begin establishing territory by mid-March, the box should be up as early as possible to increase the chance that it will be used. Once the female has arrived and chosen the nest site, it may be several weeks before the pair actually begin nestbuilding.
  • Don't be discouraged if a bluebird pair does not choose your box right away or if you get the box up a little late in spring. Because of the shortage of suitable nesting sites, there's still a chance that a pair may come along in early summer that has been unsuccessful elsewhere. Also, you might get a tree swallow, chickadee or wren using your box instead. That's okay! These are native species, and they're using your box because there are not enough tree cavities in your area to go around. Put up more boxes!
  • Face the opening of the box away from prevailing winds and in the direction of a distant tree if possible. The tree will become a landing point for young bluebirds when they first leave the box; they'll need a safe haven to avoid landing vulnerable on the ground.
  • Mount the box on a sturdy pole between three and six feet off the ground; eye-level is usually fine and makes it easier to monitor the box. Avoid placing the box near shrubby areas where wrens may dominate. Do not install the box on a tree where black snakes can easily access it.
  • Construct or install a predator guard over the entrance and also on the pole below the box, to discourage raccoons and snakes. There are several types of predator guards to choose from-conical, stovepipe, Noel, etc. (see handouts listed below).
  • Since bluebirds are territorial, you will need to space bluebird boxes at least 300 feet apart from each other. When boxes are spaced too close together, bluebirds will divert energy defending territory that would be better spent on reproductive success.
  • Do NOT allow HOUSE SPARROWS to use the box! The house sparrow (weaver finch) is a non-native, aggressive species that will drive bluebirds away. House sparrows are known to kill parent birds on the nest as well as their young, if given an opportunity. Since house sparrows tend to prefer nesting near buildings, you can deter them in part by locating the bluebird box away from buildings and out in an open field instead. Also, you can try removing the sparrow's nesting material as it tries to build a nest. (Since the house sparrow is legally defined in Virginia as a nuisance species, it is legal to remove and/or destroy house sparrow nests and eggs.) Although fairly persistent, the house sparrow may give up and move on.
  • Bluebirds generally breed between April and the end of July. They may lay from three to six pale blue eggs per clutch, with an average of four or five. (Bluebirds often have at least 2 clutches and sometimes even 3 over the course of the breeding season.) The female incubates the eggs for 12 to 16 days, while the male assists in feeding her.
  • You can check on the eggs and the nestlings once a week until the young are about 12 days old. Contrary to popular opinion, human "scent" does not cause the parent birds to abandon their young, because birds have a poor sense of smell. Take notes about what you find! After the birds are 12 days old, it will be best to observe the box from a distance, because disturbing the young later than this may cause them to "fledge" or leave the nest prematurely, which might reduce their chance of survival. Young bluebirds generally leave the nest between the 17th and 20th day after hatching.
  • Once the young have left the nest you may clean the box out. Bluebirds typically re-nest a second and sometimes a third time during one season, and they frequently use the same box over. If you do not clean the old nest out in time, they will either build a new one on top of the old or they will look for an entirely different nest site. This is why having more than one box up in the vicinity can be beneficial.

Additional Resources

Here are some resources to help you learn more about attracting bluebirds:

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