It’s Prime Bluebird Nesting Season Now.

In most areas of North American, it’s prime bluebird nesting season right now. Male eastern bluebird The only exceptions might be in some of the high elevation areas of the west where it can still be quite cold.  But whether you have Eastern, Western, or Mountain bluebirds, the #1 these gorgeous birds are looking for that we can provide is a nesting box.

All bluebirds are what’s known as secondary cavity nesting birds.  That means they prefer to nest in hollowed out cavities in trees AND can not create the cavity themselves.  They depend on natural decay in the wood or other species of birds like woodpeckers to make the cavities.   A nesting box imitates a natural nesting cavity and bluebirds are always actively looking for new place to raise their young in early spring.

Bluebirds prefer wide open, grassy habitats like farmland, pastures, meadows, golf courses, and open subdivisions.  So, if you live in an open habitat with lots of fields and grassy areas, you may be able to attract “America’s Favorite Bird”.

The easiest way to attract bluebirds is to put up a bluebird house (or nesting box) on a metal pole in a very open grassy area of your property.  The pole should be about 5 feet high after installing it in the ground (which may need to be around 12 to 18 inches more depending on how loose your soil is.

You can make a bluebird house or buy it.  They come in a lot of varieties and shapes.  But, the most critical features are:

  • At least a 1 1/2″ diameter entrance hole – 1 9/16″ is better for Western and Mountain bluebirds.
  • Thick wood construction – at least 3/4″ cedar or pine is best.  Also, recycled plastic is becoming a more popular material.
  • Ventilation gaps or openings at the top.
  • A side or front panel that can be swung open for nest checks and cleaning out.
  • An overhanging roof in the front of at least 2-3 inches for cooling and shelter from wind-driven rain.

Once you put up the nesting box, you’ll also want to protect the pole from climbing predators like raccoons or snakes.  A metal predator baffle like the one shown in the picture work well.  You can also try waxing or greasing the pole to prevent easy climbing.

Another important task to ensure greater nesting success of your bluebirds is to periodically opening the box to monitor what’s going on.  This can be done once or twice a week and involves quickly checking inside the box to see if birds are nesting, what species is nesting, and whether there is any evidence of problems from predators or insects.  Also, you need to check if house sparrows are attempting to nest in the box.  House Sparrows are common across much of North America and are very aggressive, non-native invasive birds that will kill bluebird adults and young sometimes.  Remove their nests if you find them in the box.

Bluebirds build a tighly woven nest out of grass and/or pine needles.  The female will lay 3-6 pale blue eggs (sometimes white though) and sit on them for about 12-14 days.  Then, the young hatch and will take another 16-18 days before they are ready to leave the box.  After that, they will stay with their parents for at least two weeks while learning to feed on their own.

You can also attract bluebirds by putting out birdbaths, feeders, and planting shrubs and trees they’re attracted to.  But that’s a topic for an entire other article!

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Cornell Lab of Ornithology