• Cowbird nestling among the thrushes, note the very red gape (read below).

Brood Parasitism

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Photo #3

According to Cornell Ornithology (link above), Wood Thrush are susceptible to Cowbird parasitism.
I noticed one nestling above had a gape of a different color than the others. According to Sialis: A cowbird nestling has a deep pink or cherry red mouth. Apparently an indicator that a nestling has not been fed recently is blood collected around the mouth. After the baby is fed, blood is drawn to the digestive area, and the color of the mouth fades. Thus having a bright red mouth, and the ability (due to earlier hatching and larger size) to reach higher when gaping results in Cowbird nestlings receiving priority for feeding. (www.sialis.org/cowbirds.htm)
In subsequent photos, it's clear that the nestling with the red gape reaches higher than its nest mates and receives first attention. Sadly.

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Activists for birds and wildlife

lightloverLori, maryalley904, and 10 other people added this photo to their favorites.

View 14 more comments

  1. 1F Photos 100 months ago | reply

    Someone once told me that the Brown-headed Cowbird is a native species and therefore protected. I never verified that, but I doubt that prosecution would be as severe as say with a bald Eagle chick ;-). Apparently the species once followed the Bison herds to obtain food and since constantly on the move adapted the behavior of leaving their eggs in others' nests for raising. It was a practical means to perpetuate the species. I'm not saying I like it!

  2. Laney Bird 100 months ago | reply

    Kelly, fantastic photo and information. I despise cowbirds as well, and have noticed a pair at my feeders, which of course concerns me greatly because that means nest parasitism is going on nearby. But like you also mentioned, they adapted a technique that obviously works well for them, and I guess it's hard to begrudge them that. I just can't think about it too much.....

    Fantastic Image!
    Seen in: "Winged Wonders" Post 1, Award 2

    You deserve another "Winged Wonders" award!

  3. Maureen Sullivan. 100 months ago | reply

    Fantastic shot! While I know about Cowbird parasitism this is the first image I've seen showing it.

    Fellow member of the Flickr Bird Brigade
    Activists for birds and wildlife

  4. juleen57 100 months ago | reply

    Great capture, well done!!
    Awesome Capture!

    Thank you for adding this wonderful image to The Neighborhood Ecologist.

  5. Christian Hunold 100 months ago | reply

    I watched a house wren feed a cowbird fledgling this evening, which was amusing because of the size difference. I watched a song sparrow do the same thing last week. Cowbirds are not a threat to wrens, thrushes, and so on, though I gather they have decimated a rare species of warbler or two whose numbers have already been decimated by large-scale habitat loss in N. and S. America. But they're native to North America. Brood parasitism is a sustainable survival strategy as long as only one or two species do it, and we don't destroy the target species' habitats. Which we're doing handily, of course, just having added a chunk of the Gulf Coast to lost habitat status.

  6. Kelly Colgan Azar 100 months ago | reply

    Interestingly, as I was shooting the above nest, a group associated with the parks service was removing invasive cray fish from a nearby water way. I agree that if the damage being done by brood parasitism is not threatening the long term survival of a target species, we ought to take a hands off approach. However, I have more trouble with the native/alien species concept as it seems to draw an arbitrary dateline in the sand. Our short lives make a thousand years seem significant, but natural selection takes a longer view.

  7. maia bird 100 months ago | reply

    Very thoughtful discussion, and like Maureen, I have never seen an image of it like this! I'm afraid I would be directing my husband with his cherry picker, even if it were on public property! Although it is easier to remove an egg, much harder with a live bird. Tough dilemma!

  8. Kelly Colgan Azar 100 months ago | reply

    That's very funny, Maia :-) :-) Does your husband take long range direction? Perhaps a bird rehab would raise the cow bird; there's one not too many hundreds of miles distant. I am not looking forward to chronicling the failure of this nest, but perhaps the stronger of the thrush nestlings will fledge. The Sibley Guide to Bird Life and Behavior cautions birders to no more than stop briefly in nesting areas so that predators won't be attracted to the nest. With that in mind, I may avoid the area entirely.
    Thanks so much all, for the interesting, thought provoking comments!

  9. Bertrando© 100 months ago | reply

    Fantastic Image!
    Seen in: "Winged Wonders" Post 1, Award 2

    You deserve another "Winged Wonders" award!

  10. Gnaturalist 100 months ago | reply

    Excellent image (even though I’m still not convinced that the Wood Thrush actually exists after hearing them but never seeing one in fifteen years of looking).

    Seen in: "Winged Wonders" Post 1, Award 2

    You deserve another "Winged Wonders" award!

  11. Gnaturalist 100 months ago | reply

    I do find the animosity towards Cowbirds and other bird species disturbing, particularly from people who would declare themselves as bird lovers or "activists for birds and wildlife". Cowbirds are a native species which did follow the bison herds. Once we eliminated the bison herds and removed much of the continuous forest in this country, their range has greatly expanded. Evolution led to their breeding strategy which is obviously successful. I wonder why the European Cuckoo which uses the same breeding strategy is a loved and admired bird. If it is any consolation, Cowbirds sometimes parasitize the American Goldfinch which doesn’t feed their nestlings any insect matter and the Cowbird chicks in those cases always die as the vegetarian diet is insufficient.

    In any event, animosity against this and other bird species leads people to think it is okay to control them, shoot them, etc. with perhaps unintended consequences – such as Rusty Blackbirds being in peril as a side effect of attempts to control other black bird species (Crows, Starlings, etc). Barred Owls which are"naturally" expanding to the northwest are now being “controlled” to help save Spotted Owl populations - I am sure as I’m standing that will backfire.

    The Red-bellied Woodpecker robs eggs and nestlings - should we despise that species? Wrens routinely break other birds eggs - another species to hate? Of course hawks and eagles eat other birds - and some people hate them for doing that. Cormorants are supposedly eating all the fish - so many people want them to be controlled. Birds are here and behave according to their nature. You either appreciate them for what they are or you don't. Human meddling and overpopulation and squandering of resources has led to an unnatural imbalance. Sometimes and with a lot of consideration beforehand, it may be prudent to try to restore some balance (e.g., eliminating cowbirds around Kirtland Warbler nesting areas).

    Now let me jump off my soapbox and go mow the grass.

    Member of the Flickr Bird Brigade
    Activists for birds and wildlife

  12. Kelly Colgan Azar 100 months ago | reply

    Please! Accusing others of "hate" has become entirely too common these days. On whatever the topic, it seems one can score moral points by accusing those with different ideas of "hate". It's the all purpose bludgeon.
    If by hate you mean the theoretical removal of the cowbird chick from the nest in the photo, a simple human moral equation was applied: if the several thrush chicks in the photo appear to be starving to death as the cowbird thrives, the cowbird chick might be removed to an alternate site - a bird rehab. It's not policy and it's not hate, it's an expedient to save the lives of the thrush nestlings which I have observed struggling to be fed.

  13. Gnaturalist 100 months ago | reply

    You are righ and I apologize. The word "hate" was not used in any of the previous comments and I should have been more careful with my choice of words. However, the words "cowbird chick is grotesque," "revulsion at the unnatural sight," and "I despise cowbirds as well" were used in previous comments in this thread which suggested to me a level of animosity towards these birds which might lead someone reading this thread to take action against these "sneaky, lazy, nasty" birds (more words which were previously used) in a similar situation. I recently read a similar thread on another bird related photography forum which escalated to someone chiming in that they had shot fifty pesty birds that day and some of the follow up commentors, including the moderator, were happy to hear that. I wasn't happy with that and stopped using that forum.

    I trust that you and most people involved in birds and bird photography care deeply about birds. I also realize that we sometimes encounter situations like this which create a dilemma as to the right thing to do. I'm not always sure of the right thing to do. I'm fascinated when Coopers or Sharp-shinned Hawks visit my yard and in the process they have occasionally picked off a Mourning Dove or chased away a Grackle (perhaps to its doom). It's kind of interesting to watch, but I also realize that I've created the situation by putting out bird feeders which allows this to happen. I also am disturbed when I visit a National Wildlife Refuge in winter to observe / photograph ducks on the days when ducks aren't being hunted at the same refuge - are the hunters bad people? I don't think they are, they just see the world differently than I do.

    I am kind of sorry I made my comment. I just started posting bird photos to Flickr yesterday - I had been following Maia's stream for awhile and was energized by her new group which seemed like a way to do something positive about the tragedy in the Gulf. Perhaps I'll reconsider. Take care and I do hope that some of the Wood Thrush chicks make it to fledge (they can then come and hide in my trees and taunt me to try to find them).

  14. Kelly Colgan Azar 100 months ago | reply

    Oh no! Greg, I hope you will continue to post bird photos on Flikr. It's a wonderful place to see others' work and learn something, even about ourselves.
    I cannot speak for the comments of others, but I can for my own. Through the viewfinder, I saw what I thought at the time was a single thrush nestling elongate its neck a good inch above the heads of its fellows and I was repulsed by the naked, rapacious, self preservation of the feat. I thought the response was grotesque at the time and I still do. Now I know, however, that these are not siblings sharing genes that might moderate their behavior, but two entirely different species. Still, that long, long neck is imprinted on my memory along with the Tree Swallow in the road covering the dead body of its mate with its wings and other unforgettable sights.
    Anyway, Greg, you are a quality man to have joined the discussion as you have. You will make valuable contributions to our photo and thought stream. I hope you keep posting. I look forward to seeing, more difficult than a thrush to photograph, an ovenbird!

  15. Cymry Flood 100 months ago | reply

    Wow nice shot!

  16. Harlene2007 100 months ago | reply

    Excellent capture!

    Fantastic Image!
    Seen in: "Winged Wonders" Post 1, Award 2

    You deserve another "Winged Wonders" award!

  17. TusharKumar 100 months ago | reply

    A great moment captured. Thanks for the information.

  18. tereliyesajjan 86 months ago | reply

    Apart from a good shot, very interesting explanations. Thanks for sharing

  19. Cornell Lab of Ornithology 76 months ago | reply

    NW Flickr badge This photo appears on NestWatch.org, a free citizen science nest-monitoring project from the Cornell Lab of Ornithology. Thank you for Birdsharing, and for helping people learn about birds.

  20. michaelm853 3 months ago | reply

    Just found one of these in my back yard now I know what it is tanks

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