Maintaining a bluebird nest box isn't a time-intensive hobby, but it does involve consistent monitoring. It's imperative that you check on your nest box at least once a week to monitor the progress of your bluebird nest and address any problems.
How to monitor your bluebird nest box
Monitoring a bluebird nest box can be a quick process and doesn't need to take longer than a minute or two. It's important to remember that bluebirds are very accepting of human interaction and will never abandon a nest because of monitoring. However, it's usually best to monitor a nest when the adult male and female are not inside. If you're not sure of the location of the bluebirds in your nest, you can make a whistle or call to alert them to your presence.
There are two primary functions of monitoring: checking for problems and hazards and recording the progress of your bluebird nest. For this reason, you'll want to have a log book to record things such as when bluebirds arrive, lay their eggs, hatch, etc.
Monitoring in early spring
In the spring, before bluebirds arrive, you want to check and make sure your bluebird nest box is ready for the upcoming breeding season. Look for holes, cracks or other damage. It's also a good idea to make sure that the size of the entrance hasn't been altered by other birds. Lastly, make sure that wasps haven't built a nest on the ceiling of your nest box, as their presence will prevent bluebirds from nesting.
Bluebird courtship and nest building
Male bluebirds will arrive before females to establish territory. Their arrival dates depends on geography, as bluebirds arrive at warmer destinations earlier, but the general range is between mid-February and June.
Once the male arrives, he will attempt to attract the female through a courtship flight. This will often occur around the nest box. If the female likes the male and the nest box, they will begin building the nest immediately. Nest construction takes on average 4-5 days.
Monitoring egg laying
Eggs are laid in the morning, between 7:00 a.m. and 9:30 A.M., and you should avoid monitoring around this time. The female will lay an egg a day, sometimes missing a day if it's cold or rainy. The number of eggs laid varies by bluebird species, but will usually be no more than eight. The female will spend time away from the nest during the egg laying period, but if you do open the nest box while she is there, you should be able to lift her off the eggs and count them without incident.
The female will not begin incubation until she has laid her last egg, after which the incubation period will last approximately 14 days. During this period, you want to make sure that the nest box remains warm and dry. If a nest gets wet, it will aversely affect incubation, possibly preventing birth. If you find that your nest has become wet, you can construct one on your own and switch it out with the nest in your box.
During the first few days after young birds are hatched, the father brings them food, while the mother continues to remain on top of the nest to keep the nestlings warm; this is called brooding. You may notice the adults departing the nest with a white blob in their bills. These are fecal sacs, which the adults remove from the nest to keep it clean.
During the nestling stage, the most important function of monitoring is to ensure that the nestlings aren't attacked by predators. House sparrows, raccoons, cats and even snakes will all prey on newly-born bluebirds. If you find an injured bluebird, you can take it to a wildlife rehabilitation clinic to be tended to.
After approximately 20 days, the nestlings will become fledglings and leave the nest. If you make it to this stage, you will have successfully raised a new brood of bluebirds!
Ready to purchase a bluebird nesting box? Check out our bluebird house collection. Want to learn more about bluebirds? Check out the other articles below.