It’s officially summer, and we’re not the only ones noticing that things are heating up! Wild birds are also looking to beat the summer heat, especially as many are nesting and raising young. And nest boxes, meant to keep vulnerable eggs and young birds warm and protected, can also cause them to overheat in high temperatures. Here are a few things you should know, and solutions for keeping your nest boxes cool in hot summer weather:

How Hot is Too Hot for Nest Boxes?

A Western Bluebird flies into the entrance hole of a nest box, with a forest of trees in the background.

Climate change has caused temperatures to soar around the globe, and wild birds are feeling it. (In fact, there is evidence of some birds nesting earlier in the year to prevent their chicks from overheating.) Here in Southern California, Chirp’s “headquarters,” we are no strangers to hot and dry weather. And while it rarely gets higher than the low-80s here in Big Bear Lake, the temperature in nest boxes can run at least 10 degrees hotter, so it’s good to keep watch on them. So how hot is too hot for nestlings? A nest box temperature of 107degrees or hotter can be lethal to eggs and young birds.

How to Keep Your Nest Boxes Cool in the Heat

Relocate your nest box to a shady spot

A wooden nest box mounted on a tree trunk in the shade.

This is only recommended if the nest box is empty, since moving a full nest box is stressful, and can be harmful, to nesting birds and their young. It’s always a good rule of thumb to mount a nest box in an area that’s not in direct sunlight, particularly afternoon sun. Placing a nest box in a shady spot can reduce its internal temperature significantly. You can mount or hang them under a tree limb or in a place with dense shrubbery. (And for birds, like bluebirds, that prefer nesting out in the open, just be sure that the shaded nest box has a clear line to an open space.)

Add some shade over your nest box

If you already have birds nesting in your nest boxes, or if moving your nest boxes isn’t an option, you can always create shade. Hang a sunshade or some type of fabric to block the nest box from the sun (particularly in the afternoon, the hottest part of the day). Some have even attached an umbrella over their nest box with good results.

Give your nest box some ventilation

More airflow means less heat, so get ready to overhaul your nest boxes! It’s not as difficult as it might seem at first. You don’t have to be a DIYer to do it; simply drill a few small holes in the top side of the box. You can also use something to prop open the top of the nest box so that there’s a small gap where hot air can escape. Just be sure to keep the gap small, to prevent predators from getting in.

Add a second roof to your nest box

A bird peeks out of the entrance hole of a nest box with an added roof that creates more shade.

Adding a temporary “double roof” to your nest box adds a second layer of heat protection from the blazing sun. And, since you’ll only need it for extremely hot weather, you can make this second roof layer as permanent or as temporary as you like. For instance, if you want a “set and forget” layer of sun protection, you can use a small piece (18” x 24”) of wood and screw it on top of the nest box roof. This creates a new roof with a larger surface area, providing more shade from the overhang, and a thicker layer for heat protection. You can do the same with a piece of Styrofoam and tie it down with elastic or use push pins for a more temporary solution.

Place a birdbath near your nest box

A sparrow seems to skip along the edge of a concrete birdbath.

You’d be amazed at what adding a birdbath can do for your wild birds. A clean, cool water source is essential for wild birds, who use it for drinking and bathing. Particularly in the hot weather, birds—like us—need to cool down, and a nearby birdbath is a godsend! Just be sure to keep the water clean, refreshing it every few days. And make sure your birdbath is in the shade to prevent the water from heating up.

Paint your nest box a light color

In places with extreme heat, painting the exterior of your nest box white, or a light color, can help deflect the heat. In some cases, white nest boxes are up to 8 degrees cooler than unpainted nest boxes. Just be sure to keep the inside unpainted, as the paint may be toxic to birds and their young.

Your Free Summer Reading List

A Western Bluebird perches on the top of a birdhouse, seemingly basking in the summer sun.

From attracting birds to your feeders this summer to keeping them safe from extreme heat, Chirp is your trusted source for caring for wild birds in this (and every!) season. Here are some of our favorite summer resources: