Aug 18, 2021 | Featured in: Watching Backyard Birds, August 2021

Ask Birdsquatch: One Female and Two Male Western Bluebirds Tending One Nest?

Western bluebirds occasionally have nest helpers. The term for this is cooperative breeding, and it has been well documented.

Dear Birdsquatch:

This sounds crazy, but I swear there were two daddy bluebirds in my nest box this summer. I saw only one female, but two males regularly brought food to the nestlings. Do you think Mrs. Bluebird had two husbands? Did she lay eggs from both males? The nest was in a hole in a tree in my yard, so I couldn't peek inside. I don't mean to be judgmental, but what the heck was going on in there?

—Elza B., Mill Valley, California

Dear Elza,

Western bluebirds occasionally have nest helpers. The term for this is cooperative breeding, and it has been well documented. Those helpers can be juveniles (usually males) from a previous brood, adult pairs (presumably after their own nest has failed), or adult males.

While western bluebirds do form pair bonds—one female and one male pair up to raise young for one season—genetic testing shows that nearly half of western bluebird nests contain young that are not fathered by the paired male. Mama bluebird gets around, and the young ones in the clutch often have multiple fathers. So, you're right: There probably was hanky-panky going on. But don't feel sorry for Mrs. Bluebird's husband: Western bluebird nests with helpers tend to fledge more chicks than nests without helpers, which is why cooperative breeding is generally a peaceful affair.

About Birdsquatch

Birdsquatch is WBB's tall, hairy, and slightly stinky columnist. He is a bigfoot who has watched birds all his life. His home range is unknown.

What do you think? Tell us!

New On This Site

The Latest Comments

  • 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
  • This breaks my heart. God strengthen your spirit and comfort your heart.I am fortunate to be taking a vacation next month, hopefully before sky high inflation hits and I can no longer afford it.
    by Ironweeds, Fri, 27 Aug 2021