Have you ever seen a Brown Headed Cowbird nest?

Probably not.  They don’t build nests.  They deposit their eggs in the nests of other wild bird species for the host species to raise their young.

Brown Headed Cowbird Eggs

Brown Headed Cowbird Eggs In Eastern Bluebird Nest

Don’t the hosts know they have a “foreign” egg or nestling?  Evidence suggests they do.  Some species will dispose of the cowbird egg, others incubate, hatch and rear the cowbirds along with their own.  Evidence also exists that cowbirds watch over their eggs and may retaliate if the host birds don’t accept them.

Male Brown Headed Cowbird

Male Brown Headed Cowbird

So, what did I find on my Eastern Bluebird monitor route walk today?  Something I’ve never found before.  Two Brown Headed Cowbird eggs in a nest with 3 lovely bluebird eggs.  The adult bluebird pair was in the area perched above its nest-box guarding it as usual.  In spite of the cost to their own young (they will have a difficult time finding enough food to feed the additional mouths with very large appetites) they will likely be good parents to the cowbird nestlings left in their care.

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16 Responses to Have you ever seen a Brown Headed Cowbird nest?

  1. Anonymous says:

    I have a robin nest with cow birds hovering near by. Thought about removing the cow bird eggs. Guess I will just leave it up to nature. Robin may desert nest if I interfere.

  2. Just Rod says:

    Fascinating information. I knew that about cuckoos but not Brown Headed Cowbirds.
    Thanks for looking at my blog and the foll

    • I was heartbroken to find Mr. and Mrs. Bluebird ultimately abandon this nest. They likely knew their own would suffer and perhaps perish because they would not be able to feed all those mouths. Thank you for stopping in and commenting!

  3. I love that you take time to enjoy birds! My oldest son, Caleb, is legally blind, yet a major nature-lover. When he was little, we did a lot of bird-watching, which was very difficult for him, but really rewarding. He is now is his senior year at CSU with a major in natural resources, recreation, and tourism. (He tried forest biology, but it was too difficult.) I sometimes forget how wonderful birds are, so I appreciate stopping by your blog!

    • Wow, Mollie! First, thanks for the wonderful compliment and for stopping in.

      Second … I am trying to build a birding website (it’s slow going … not ready to unveil it yet) and my longer-term goal, once I flesh out the basics like birdbaths, bird houses, bird feed, binoculars, etc., is to include something of interest to those who are physically challenged. I don’t know what kind of audience there would be, but I eventually want to make it into a mega-site to make information available for birders of all ages, all interests, all around the globe and wildlife tourism.

      I’m so happy your son is enjoying studies involving his passion!

  4. Interesting… In the Bahamas the shiny cowbird does the same with smaller birds – yellow warbler and blue-gray gnatcatcher for example. If the host bird notices and takes action (turfs out the alien eggs or covers them with nesting material) the cowbirds may attack the nest, as you note. [Not sure how you came to call in at Rolling Harbour, by the way, but welcome!]

    • The Brown Headed Cowbird used to follow buffalo herds on the American plains. They could not linger to incubate their nests as the buffalo herds moved on, so they left their eggs in the care of others. I don’t suspect there are buffalo herds in the Bahamas. I had the pleasure of visiting once, and didn’t see any. 😉

  5. Deb Platt says:

    Later in the summer I usually see a foster parent teaching his / her cowbird baby how to use the bird feeder. They are very attentive to their foster child, but I typically don’t see the same parent feeding any of its own, genetic children. I think the genetic offspring often don’t survive.

    • That is true. Many times the host species raises the cowbird at the expense of its own young. Nature has strange ways, doesn’t she?

    • Rebecca says:

      Deb Platt, you are so correct. And what is the best action to take when one discovers cowbird eggs in the next of a much smaller bird?

      • Deb Platt says:

        There’s no good alternative. I tried removing a cowbird’s eggs from a house finch nest, and the mother cowbird came back and killed the finch chicks. I then read about this online. It’s literally called “mafia” behavior on the part of the cowbird.

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