Bluebirds begin scouting for nest sites in mid February to mid March. Timing also depends on weather. But if it’s late spring or even early summer, is it too late to set up a bluebird box?
Even in late spring or early summer, it’s not too late to set up a bluebird house. Spending on the species, bluebirds have multiple broods a year between March and August. Furthermore, nest boxes give bluebirds an important roosting haven at winter time.
Eastern bluebirds usually have 1-4 broods from a time period spanning April – August. In southern regions of the US, eastern bluebirds may even lay eggs in march.
While there is record of western bluebirds having up to 3 broods in a year, this is rare. Usually western bluebirds will have 1-2 broods per year. But the number of broods depends a lot on weather, location and timing.
The breeding season for mountain bluebirds is between April – September. However, this can also depend on weather and environmental factors. Usually mountain bluebirds will have at least one brood, but if successful, there is a chance they’ll have a second.
| Bluebird species | Number of Broods | Nesting Period (Breeding Season) |
| Eastern Bluebird | 1-4 | March – August |
| Western Bluebird | 1-2 (3 rare) | May – July |
| Mountain Bluebird | 1-2 | April – September |
Just to define what we mean by broods, a brood is like a round of egg laying. They’ll lay their first brood, the eggs in that clutch (number of eggs laid in a session) will hatch. Bluebirds will feed and care for their nestlings, and then they fledge the nest. Even after fledging, bluebirds will care for their young and teach them how to get food of their own.
After this first brood fledges, bluebirds, especially eastern bluebirds will have another brood. They’ll lay their eggs, and go for another round of raising young. Rinse and repeat.
As mentioned, western bluebirds can have up to two broods, and mountain bluebirds, if successful, may have up to two broods also.
Setting up a bluebird house late in the nesting season
Consider the table above, what this means is that if you feel a little late in setting up a box, you still have a chance of attracting bluebirds to your nest box and getting them to nest.
There are a few things to keep in mind if you’re wanting to attract bluebirds to your nest box.
- Make sure your bluebird box is away from a lot of brush. Grassy areas and meadow are attractive spots.
- Do not mount your bluebird house on a fence post or tree trunk where predators can easily get to them.
- If you have house sparrows in your area do not set up a bluebird house. House sparrows are invasive, and will kill bluebirds for their nest boxes. Adding an extra box for the house sparrows will not stop them, and will likely attract more. Allowing house sparrows to nest causes conservation issues and habitat loss for bluebirds.
Managing heat when caring for late nesting bluebirds
Bird eggs are more sensitive to heat than they are cold. We have a great article about how eggs hold up to the cold weather. But we want to provide some tips when it comes to the heat of the summer.
One of the most important things is to protect the nest box from heat. The insulative nature of the box alone will provide some assistance. Thicker wood provides better protection against heat penetration.
Some other considerations to minimize heat are:
- Ensure your nest box is a light colored wood or white. Do not use a black painted box, dark painted box, or boxes with a dark top to them.
- Do not install skylights into your nest box.Some have promoted installing skylights as a sparrow deterrent (which has not worked in our experience), but this allows heavy light penetration which can kill embryos in the eggs and nestlings.
- Ensure your birdhouse has proper ventilation. You can drill vent holes on each side of the nest box if the nest box doesn’t have good ventilation.
- You can build a heat shield which will shade the nest box and allow airflow
What supplies do I need to get started with my bluebird house?
Obviously the first supply item is a bluebird house. We recommend ones that are built according to North American Bluebird Society’s guidelines.
These birdhouses are easy to find on Amazon (see recommendation below) or at Home Depot. Here are a few things to look for when shopping for your bluebird house:
7 Things to look for in a bluebird house
- Side or front access to allow proper monitoring. Top-hatches are not recommended for a number of reasons listed in this article.
- Ensure the wood is made of a light color, and that the top of the nest box is not a dark color.
- Look to see if it is constructed according to the North American Bluebird Society (NABS) guidelines.
- Check for ventilation. You may need to add more, but that’s as easy as drilling a few extra holes.
- Check for bast drainage (gaps at the corners of the bottom to allow drainage.
- Check the inside just below the entry hole for slits in the wood to form a ladder for fledglings.
- Make sure there is an overhang over the nest box.
Our best recommendation, found here, is the Ultimate Starter Bluebird Nest Box. The only drawback is that the ventilation may not be sufficient enough during the high heat of summer. The easy fix is to drill extra ventilation holes up at the top of each sides to allow better airflow.
Additional supplies needed for a bluebird house
The other immediate supplies you’ll need to get started with your bluebird house is a pole and a baffle. You can use EMT conduit reinforced with rebar. This is easily found at any hardware store (Home Depot, Lowes, Menards).
But if you’re not quite up for the total DIY required for this mounting system, we recommend a pole with an auger and mounting bracket – also easily found on Amazon.
A stovepipe style baffle is going to offer the best protection from predators. We have a really detailed article about how to choose a baffle, but will also provide some quick tips here. At the very least, your baffle should be 8” in diameter by 24” long.
These are commercially available and easy to mount. You can also DIY this using duct piping from a hardware store.
The upside to the DIY route is that it allows you to control the size and if you have all the tools and know-how, it can save a lot of money.
Here is a list of the additional supplies, some of which are found on Amazon*
- Bluebird house – $26 – $65
- Pole kit with auger and mounting bracket – $50 – $55
- 8″ x 24″ Stovepipe baffle – $55- $60
Winter time is still a good time to put up a bluebird house
Winter can be fatal to bluebirds, cavity nesters and other native song birds. Several days of below freezing temperatures, heavy winds and precipitation with little shelter annihilates bluebird numbers.
One of the best ways to offer protection from the elements is to provide a nest box, even add some pine needles at the very least. This can serve as an overnight roosting box for several birds at a time.
Other bluebirders will take added measures to winterize their nest boxes, which requires greater detail to explain. But at the very least, putting up your nest box as a roost box can help ensure their survival.
If you’re new to bluebirding, a winter box can give you some extra time to learn more about the importance of monitoring and caring for your bluebirds.
Be sure if you are providing winter shelter that you do not prevent any other native cavity bird from roosting in these boxes. At the same time, take extra care to prevent invasive house sparrows and starlings from occupying these boxes. As a want-to-be bluebird landlord, enthusiast or student, putting a box in your yard obligates you to an important responsibility to help conservation efforts and not hurt them.
In summary, even if it’s already June, you might still have a shot at getting some bluebirds, so go for it. And if it’s in the middle of winter, adding a properly mounted bluebird box to your yard can be a matter of life or death for these native cavity nesters.
