The Cowbird Conundrum
My head cold is starting to subside. Non Birding Bill and I are hangin' at Mr. Neil's this weekend to keep an eye on the newly installed bees and to prep for banding on Sunday. The rain is making for some interesting feeder watching. Outside the kitchen window I can see a pine warbler and a black and white warbler going for the suet feeder. On the one hand this is exciting to see. On the other hand, I know these insect eating birds are desperate on their migration if they are eating peanut butter suet.
Thanks to a note left by Minnesota BirdNerd in the comments, my mind has been totally blown by the brown-headed cowbird theory. For years many of us have spouted the reasonable sounding defense of the brown-headed cowbird: they followed herds of bison on the prairie in North America, eating insects that were kicked up and evolved over time to deposit their eggs in the nests of other birds since their traveling lifestyle meant that they couldn't stay in one place long enough to build a nest, incubate eggs, and raise young. However, nomadic herds of bison are no longer in existence, brown-headed cowbirds follow sedentary humans and wreak havoc on nesting birds.
However, Alvaro Jaramillo who wrote the book about blackbirds (literally, he wrote the book on blackbirds) has this theory:
"This cannot be true. If you look at the evolution of the cowbirds (the entire genus Molothrus) you will find that they most likely arose in South America where there are no bison. As well, the Shiny Cowbird and Brown-headed Cowbird appear (based on the phylogeny developed by studying variations in mitochondrial DNA sequence) to be the most recently derived species in the cowbird clan. Thus, by the time that the Brown-headed Cowbird arose as a species it was already part of a lineage of brood parasitic birds, it was not the first. Cowbirds were 'pre-adapted' to a nomadic lifestyle due to their brood parasitism, but this behavior did not evolve due to a 'need' to follow Bison."
So, what does this mean? Are cowbirds just downright evil? No, they are just trying to find their way in this world like the rest of us. Although, now I have to think back to all the articles I've written and my already-at-the-printer-book City Birds Country Birds that has the bison theory in it. Sigh. Curse you brown-headed cowbirds and everything you stand for!
Thanks to a note left by Minnesota BirdNerd in the comments, my mind has been totally blown by the brown-headed cowbird theory. For years many of us have spouted the reasonable sounding defense of the brown-headed cowbird: they followed herds of bison on the prairie in North America, eating insects that were kicked up and evolved over time to deposit their eggs in the nests of other birds since their traveling lifestyle meant that they couldn't stay in one place long enough to build a nest, incubate eggs, and raise young. However, nomadic herds of bison are no longer in existence, brown-headed cowbirds follow sedentary humans and wreak havoc on nesting birds.However, Alvaro Jaramillo who wrote the book about blackbirds (literally, he wrote the book on blackbirds) has this theory:
"This cannot be true. If you look at the evolution of the cowbirds (the entire genus Molothrus) you will find that they most likely arose in South America where there are no bison. As well, the Shiny Cowbird and Brown-headed Cowbird appear (based on the phylogeny developed by studying variations in mitochondrial DNA sequence) to be the most recently derived species in the cowbird clan. Thus, by the time that the Brown-headed Cowbird arose as a species it was already part of a lineage of brood parasitic birds, it was not the first. Cowbirds were 'pre-adapted' to a nomadic lifestyle due to their brood parasitism, but this behavior did not evolve due to a 'need' to follow Bison."
So, what does this mean? Are cowbirds just downright evil? No, they are just trying to find their way in this world like the rest of us. Although, now I have to think back to all the articles I've written and my already-at-the-printer-book City Birds Country Birds that has the bison theory in it. Sigh. Curse you brown-headed cowbirds and everything you stand for!
posted by birdchick at 8:02 PM
14 Comments:
Why those brown-headed cowbirds are as wiley as Rabbits.
Enjoyed the Upper Midwest accent in the bee saga!!! And the education as well. It was obvious men were not doing the reload ... I heard directins being read!
Some sort of management seems needed for the cowbird problem. And by management I do not mean a cull as so many have tried with the canada goose, which is senseless killing. Either make the nesting areas less appealing or as you suggested, when banding these birds, sterylize them in some way. It's sad that the cowbird must pay the price for our neglect of the planet because its just doing as nature intended.
It's hard to hate a bird native to N. America that is doing what they are hard-wired to do. At least in my opinion...
Never thought about them in that way, that theory is quite interesting!
I always marvel at the hatred for cowbirds, blue jays and the like by birders. These birds are incredibly well adapted and are marvels of evolution. People ascribe human traits to them such as "mean" but they are just adapted to best survive.
In there case of the cowbird, we've made changes to the habitat to favor their evolutionary adaptations but that's our fault not theirs. We are an edge species and so are they so it is not surprising that our changes help them.
Interesting stuff on the history of parasitism. It has always struck me as a smart (meaning beneficial) adaptation regardless of whether or not the species is nomatic.
Interesting theory about the cowbird. I'd have to agree that native plants and animals doing what they do best can't be all that bad. Even when it comes to species that we've introduced, I can't really blame them. It was human intervention that caused problems.
Kirk Mona - I couldn't agree more. Giving human characteristics to an animal just doesn't make sense. The cowbird is just doing what it does to survive. Humans have more choices and the intelligence to make ethical ones - birds don't.
Some cuckoos are brood parasites also, so it really is not a nomadic behavior. It doesn't make the cuckoos or the cowbirds evil – it's just what their instinct tells them to do. I think it only becomes a problem when the target is a rare or threatened species.
I don't see how this differs from 'Hoodies' laying eggs in 'Woodie's' nest boxes. If the Cowbirds were yellow or red we would love them! My only problem is that they are usually bigger than their nest-mates.
I want to kill the squirrels for eating all my black oil seeds, but, why should I select who eats and who doesn't?
I'm conflicted about the cowbirds - I just wish they would "evolve" and start taking care of their own babies.
If I remember my college Evolution class - we discussed the Cowbird. Turns out not all birds will accept their eggs....over time some birds have figured it out. Eventually, the current birds that accept their eggs will figure it out too and the cowbird will have to pick new bird species to move on to.
[Perk] Did you say BOOK? When...WHEN???
Cowbird control (killing) in the Kirtland's Warbler nesting area in MI, is probably the MAIN reason KIWAs have increased in number. The sad truth is that we are the dominant player in 'nature' today, and there will be species we HAVE to manage intensively if WE want them to continue to survive (Whooping Cranes, and California Condors to name two additional species). If 'nature' is left to her own devices we will lose species we enjoy having around. "Nature" doesn't really care what species survive, only we do. Even if the whole system unravels, there will be some life forms to take advantage of the new wholly out of balance ecosystem. We just may not be dominant anymore or we may not like whats left.
All that said, indiscriminate killing of any native species is never warranted, but sometimes if we want to help a species on the brink, we may have to control a different species.
Ever since I started birding, I've had a problem with disliking parasitic/non-native species; I just can't dislike any bird. They're just trying to survive the best way they know how; it's not really their fault. Still--I do prefer bluebirds to house sparrows, yellow warblers to brown-headed cowbirds, etc.--but I'd never hurt the parasitic/non-natives. I just don't have it in me.
I am conflicted on the parasitic birds too. I have bluebirds nesting in a box and panic everytime I see a House Sparrow. The real BB aficiandos kill the House Sparrows. I don't like them, but I just can do it. Some of them even gas them with car exhaust. I know they aren't native, but still....
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