I have a couple of birdhouses in my yard that have families nesting in them every year. I try to remember to clean them out in early spring before nesting season begins, or late fall after I’m sure the birds are done using it. I’ve discovered some of them keep very messy homes.
Robyn Bailey is the project leader of “Nest Watch” within the Cornell Lab of Ornithology. She says many birds will clean out their own nest boxes, but some don’t so it’s up to us to be their helpful maid.
"Just so that that box doesn’t fill up and eventually become unusable to those specific birds. Now some birds will clean out a box on their own using their bill to remove material through the entrance hole," says Bailey. "But, bluebirds and chickadees and a lot of our favorite birds won’t do that, so the reason we’re cleaning it out is to help them out and keep that box being useful for the 10 or 15 years that you should get out of it."
Bailey says there is research that shows leaving the nest in there is a visual cue to the birds that another bird has been there successfully. Leaving it there for a year is ok, but eventually you’ll need to clean the birdhouse so it doesn’t fill up with debris.
"Scraping out the nest box is the first step you want to do. There should be some leftover nest material, perhaps an unhatched egg, those are things you want to scrape out first. And then, using soapy water you can clean out a nest that’s been soiled by the youngsters that were in the nest the previous breeding season," she says. "If you had something else in there, like mice, that can really have a real odor that sticks to the nest box. So, I might use something stronger like one- part bleach to ten parts water."
Scrub it out with a toothbrush and the cleaning solution. Rinse it well and leave it open in the sun so it dries completely.