Apr 15, 2020 | Featured in: Watching Backyard Birds, April 2020

Bluebird Boxes and Spring Housecleaning

A western bluebird flies into a backyard nest box.

To clean or not to clean last year's nest from a bluebird box in preparation for nesting this spring—that is the question.

Research shows that bluebirds, when given the choice, overwhelmingly select boxes with an old nest in it. This goes against a popular thought that bluebirds avoid old nests due to parasitic blowfly larvae. Blowflies lay their eggs in old nests, and the larvae attack the young birds.

However, researchers say that although there is a much greater chance of blowflies in boxes with old nests, there is also a much greater chance that parasitic wasps will lay eggs in the old nests. The wasps prey on the blowflies, limiting the damage they do. The researchers also point out that bluebirds might choose boxes with old nests because the birds spend less time and energy finding nesting material.

But neither of those reasons justify failing to monitor, maintain, and even clean your nest boxes. Removing an old nest removes mites, other parasites, and feces, as well as blowfly eggs. Watching Backyard Birds recommends emptying and cleaning your nest boxes soon—before nesting season starts. Remove the old nest; sweep out residual waste material, and you're done. Do not use pesticides or cleaning solutions in the nest box. Harsh chemicals can leave residue that may harm birds, especially nestlings.

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  • I am excited to have my daughter’s tree this year, since my landlord has removed the lovely yew next to my patio, which was the only shelter for birds at my feeder.
    by pmalcpoet, Mon, 20 Dec 2021
  • Goldfinches will continue as long as Swiss chard is available. I'm watching one eating chard right now (mid-November in Vermont).
    by Brian Tremback, Sun, 14 Nov 2021
  • Birds are on the decline though sunflowers are rarely touched and for weeks hardly .eaten. I'll try a few sparing nuts on the table and a fat ball broken for jackdaws and tits but mealworms were a summer favourite being my go to choice
    by Paul Harabaras, Thu, 04 Nov 2021
  • I’ve been enjoying goldfinches eating coneflower/ echinacea seeds in my new pollinator garden! I will leave the plants out all winter for them if the seeds keep that long? Or should I deadhead and put them in a dry area? Im in CT and thought they migrated, but didn’t know they put in winter coats! What do they eat in winter without bird feeders?
    by Anne Sheffield, Sat, 04 Sep 2021
  • Hi Gary, I will pass your question along to Birdsquatch next time I see him. He knows infinitely more about nocturnal wildlife than I do. Where do you live? That's pretty important in figuring out the answer. But the thief could be raccoons, deer, or flying squirrels. Do you live in the woods? Are there trees near your feeder, or must the culprit climb a shepherd's hook or pole? Dawn Hewitt, Watching Backyard Birds
    by Dawn Hewitt, Mon, 30 Aug 2021