Skip to content
August 24, 2013 / Leslie

Weekend Birding: Who’s Your Daddy?

This is a Northern Cardinal feeding a recently fledged Brown-headed Cowbird. Why? Because a female Cowbird substituted one of her eggs for a cardinal egg when no one was minding the nest.

The cardinals raised this chick as one of their own and didn’t seem to notice that it doesn’t remotely resemble a young cardinal. (While Mr. Cardinal was feeding the cowbird his own son/daughter was hiding in my apple tree and then emerged to sit on the back fence.)

Cardinal feeding Cowbird

Brood Parasites

Cowbirds do not build nests or raise their own young. Instead, they lay their eggs in the nests of other species hoping that bird will rear their young. Over 144 species have been documented as cowbird foster parents.

Female cowbirds spend their days stalking other birds to locate their nests. When they find one they will toss out one of the host’s eggs and quickly replace it with one of their own. Many birds never notice the difference. Some birds do notice and will abandon the nest or build a new nest on top of the old one, and others may eject the offending egg.

Female Brown-headed Cowbird

Adult Female Cowbird

The female cowbird remembers where she has deposited her eggs and periodically returns to check on them. If her egg is missing she may lay another one or, if the host’s eggs are too close to hatching, or perhaps in a fit of revenge, destroy the nest forcing the host to build a new one. This mafia-like behavior was actually documented in a scientific study.

Cowbird young have a short incubation period usually hatching a day or two before the bird’s own young. They also have a voracious appetite and grow quickly often to the detriment of the host’s young. We like to think that the parents provide the same amount of food to each of their nestlings, but that is not the case. They feed the baby who opens his mouth the widest and this is often the large cowbird. The cardinal host parents in my yard were also able to raise one cardinal, however a normal, non-parasitized, nest would have produced three or four cardinals.

Male Brown-headed Cowbird

Adult Male Cowbird

Interesting Facts:

  • Cowbirds are promiscuous, there is no pair bond. Males and females have several different mates within a single season.
  • A female can lay 35 to 40 eggs per nesting season.
  • Cowbirds will lay eggs in the nests of more than 220 species of birds.
  • It is theorized that cowbirds became parasitic because at one time they followed roving herds of bison and had no time to stop to nest.
  • Cowbirds can be found across most of North America.
  • Cowbirds do not “imprint” on their foster families and will join up with a flock of other cowbirds after a few months.


Saturday Snapshot was originated by Alyce at At Home With Books. For the summer it will be hosted by Melinda of West Metro Mommy. Visit her blog to see more great photos or add your own.

© 2013 Under My Apple Tree. All rights reserved.



Leave a Comment
  1. Arti / Aug 24 2013 9:51 am

    I learn something new every time I visit your blog. Now this is most interesting. I can understand the reactions of those birds that would ignore or build another nest on top of their own, but I’m really surprised to see birds raising a different species, esp. one that looks so different from their own… like this Cardinal. Impressive photo that first one!


  2. Marie / Aug 24 2013 9:58 am

    Great post, Leslie. I love the title. Last year we had a cowbird invade a Eastern Phoebe’s nest. All of the phoebe eggs were thrown onto the ground, so no phoebes were raised. They probably wouldn’t have survived anyway. The nest was barely large enough for the cowbird that hatched. I was really looking forward to seeing the babies and was so disappointed when I saw it was a cowbird.

    The phoebe’s returned this year, but nested further away and I didn’t get to peek into the nest. I’m hoping they had better luck. The cowbirds also returned so there’s a chance that someone is raising a baby cowbird.


    • Leslie / Aug 27 2013 12:31 am

      That’s the biggest problem, the host’s young often don’t survive. I watched a webcam of a Phoebe nest a few years ago and it had two cowbird eggs and one Phoebe egg. Those cowbird chicks were huge in comparison. Fortunately they fledged quickly and the baby Phoebe survived.


  3. BermudaOnion / Aug 24 2013 11:09 am

    What a fabulous photo! I’ve heard of cowbirds and their nesting habits but don’t think I’ve ever seen a photo like this.


    • Leslie / Aug 27 2013 12:34 am

      I’ve been trying to get this shot for years!


  4. Beth Hoffman / Aug 24 2013 11:39 am

    Wonderful and informative post, Leslie! The pic of Mr. Cardinal feeding the cowbird chick warms my heart.


  5. Suko / Aug 24 2013 11:44 am

    Truly fabulous photos, Leslie! And thanks for the bird info. Their behavior is interesting and fun to learn about.


  6. readerbuzz / Aug 24 2013 12:05 pm

    That is fascinating! I hope you are working on a book about birds….

    Here’s my Saturday Snapshot!


  7. booketta / Aug 24 2013 12:11 pm

    Beautiful cardinal 🙂


  8. MarthaE / Aug 24 2013 12:18 pm

    What good images and great information you shared! Thanks.


  9. laurelrainsnow / Aug 24 2013 12:23 pm

    First of all, love that catchy title to your post! And the story of cowbirds is completely new to me, like most of the facts you share each week. Those cowbirds are like some people I’ve known…lol

    Thanks for sharing…and for visiting my blog.


  10. postingfornow / Aug 24 2013 2:24 pm

    Amazing photos and story!


  11. Diane@BibliophilebytheSea / Aug 24 2013 5:22 pm

    Interesting info and great pics – thanks


  12. Christine Harding / Aug 24 2013 6:01 pm

    Presumably they are like are cuckoo then. Fabulous photos, and some fascinating informayion to go with them.This week I’ve shifted my Snapshot on to my other blog


    • Leslie / Aug 27 2013 12:42 am

      Yup, the cuckoo is another bird that lays its eggs in another species nest.


  13. Louise / Aug 24 2013 7:19 pm

    Another stellar post Leslie. That first picture is amazing. You’ve told us about cowbirds before, it’s an incredible story- amazing that they have a shorter incubation so get out before the host chicks. I think the most extraordinary point is that last one that they don’t imprint and go join cowbirds. I’ve never thought about what cuckoos do, but I suppose that they must do a similar thing as they grow. They break what seems to be every strong bird behaviour and use it to their advantage.


    • Leslie / Aug 27 2013 12:45 am

      That’s the fascinating part… how does that chick know it’s a cowbird and not a cardinal? And I have seen small groups of juvenile cowbirds with an adult male, so somehow they are rounding them up after the breeding season ends.


  14. irene / Aug 24 2013 8:20 pm

    I wish I knew enough about birds to recognize these birds, my son and I watched a dad feeding a small bird and it was amazing, the patience. Great info.


    • Leslie / Aug 27 2013 12:47 am

      One of the most common birds to see feeding their young after they’ve left the nest is the robin.


  15. Mary / Aug 24 2013 8:38 pm

    The photo made me laugh – interesting info, Leslie!


  16. Susan / Aug 25 2013 6:40 am

    Such an interesting bird … and such a great capture!


  17. sagustocox / Aug 27 2013 4:27 am

    That is fascinating that the Cow Bird relies on others to raise its young….and that the foster parents seem to take to it so well. Wonderful. Thanks for teaching me something new.


Comment are welcome. Thanks for stopping by.

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: