Every other Friday, the Outside/In team answers one listener question about the natural world.
This week, Brittany asked: "Do birds prefer birdhouses that are natural wood or painted? All four of my birdhouses are painted, and they never seem to have a problem with attracting birds or being filled year after year."
Outside/In’s Catherine Hurley looked into it with host Nate Hegyi.
Transcript
This has been edited for length and clarity.
Catherine Hurley: Any guesses, Nate?
Nate Hegyi: I would imagine they don’t care what it looks like. They’re just like, “Hey there’s a shady hole I could go hang out in. I will go there.” Whether it’s yellow or fluorescent pink, or just regular old brown. That’s what I think.
Catherine: I think you’re on the right track. There actually hasn’t been conclusive research about whether birds have a preference for things like paint or color, or whether residual fumes are harmful to birds.
There are a handful of studies looking at really specific circumstances — like whether hummingbirds have a color preference for artificial feeders, whether you see one that’s red or one that’s blue. But it’s hard to draw wide conclusions, and so guidance I’ve heard for best practices is to leave birdhouses unpainted.
Nate: So boring birdhouses — they’re the best birdhouses.
Catherine: Well, I did also learn that ornithologists don’t necessarily use the word “bird house” at all in their research. They refer to them as nest boxes — because birds really only use them for nesting, not a year-round home.
Nate: Ok, so I shouldn’t be calling it a birdhouse. I should be calling it a nest box. I have a really nice nest box outside my garage.
Catherine: There is one thing I learned birds do care about.
Nate, imagine you’re trying to buy a house. House #1 is designed perfectly, it passes the inspection, but it’s painted a really hideous lime green color. House #2 is the exact color you’re looking for, but it’s completely falling apart. Which house do you buy?
Nate: Definitely lime green color! Easy to repaint — not so easy to rebuild an entire house.
Catherine: That’s a good answer, and it’s safe to say that birds are thinking something similar.
I talked to Robyn Bailey. She works at the Cornell Lab of Ornithology managing the NestWatch Project, which is a nationwide program that tracks trends in the reproductive biology of birds.
Robyn Bailey: Birds do ultimately choose nest boxes that are safer and higher quality and longer lasting.
Nate: So it doesn’t matter the color, just so long as it’s a good, quote, “nest box.”
Catherine: And like I said earlier, birds’ preferences aren’t super clear, per se. But there are a few things you can do to make sure your nest boxes are as safe as possible.
Robyn told me the worst thing for birds is shoddy construction.
Robyn Bailey: Anything that is stapled together or just simply glued together is not going to hold up and may not survive a nesting season.
Catherine: NestWatch recommends using untreated, unpainted wood held together by screws to build your nest box. Cedar, spruce, and white and yellow pine are all good options to prevent rotting.
Your box should be large enough for birds to build a nest and raise a clutch of eggs into young birds.
Nate: Okay, but what about the actual door to a nest box, the hole? Don’t birds need to be able to go in and out?
Catherine: That’s a must. Robyn says you definitely don’t want an entrance that’s too large.
Robyn Bailey: What this is doing is allowing predators to enter the box, or to perch in the entrance hall and reach through the entrance hole to grab the eggs or young.
Nate: Okay, so not big enough for, I dunno, a fox to climb up and stick his head in there — but still big enough for the bird to get in.
Catherine: Exactly, and it’s good to clean out the box at least once a year. If you want to build your own nest box this summer, you can check out NestWatch’s website for floor plans and construction guides.
Nate: We should send those out to the shop classes throughout the country, because I feel like that’s where half of the birdhouses are built.
Catherine: Make sure those middle schoolers are building really safe nest boxes!
If you’d like to submit a question to the Outside/In team, you can record it as a voice memo on your smartphone and send it to outsidein@nhpr.org. You can also leave a message on our hotline, 1-844-GO-OTTER.
