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Roadkill Forcing Cliff Swallows To Evolve

sciencehabit writes "Cliff swallows that build nests that dangle precariously from highway overpasses have a lower chance of becoming roadkill than in years past thanks to a shorter wingspan that lets them dodge oncoming traffic. That's the conclusion of a new study based on 3 decades of data collected on one population of the birds. The results suggest that shorter wingspan has been selected for over this time period because of the evolutionary pressure put on the population by cars."

31 of 387 comments (clear)

  1. Re:first by pecosdave · · Score: 5, Insightful

    That will be the downfall of your species. Those who march in front are merely the meat-shields for the warriors that follow, the first torn down by the musket balls and horse mounted cavalry while those behind remain to actually fight.

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  2. Tricky EIRs by Anonymous Coward · · Score: 3, Interesting

    This could be tricky, if this gets classified as a new species, how do we factor in the need for persistant traffic in environmental impact reports? If we cut traffic this species would lose its competitive edge and thus habitat and could become extinct!

    1. Re:Tricky EIRs by Luckyo · · Score: 3, Informative

      No. The change is likely morphological rather then genealogical. As a result they will stay the same species, just like dogs do.

    2. Re:Tricky EIRs by cusco · · Score: 3, Informative

      Depends on which definition of 'species' you use. Grizzly bears and polar bears can physically interbreed, but they don't. Are they the same species? Some biologists will say yes, others will say no. Species is one of the messier words in science.

      BTW, **NINE** digits of years? 100 million or more? Only three million years ago we were Australopithecenes, do you actually think Homo Sapiens haven't made 'long term' changes in the interim? 70 million years ago we were rat-sized egg-laying insectivores, are you really sure that we haven't changed significantly since then?

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    3. Re:Tricky EIRs by Zalbik · · Score: 3, Informative

      Just wondering how long it will take you to realise that none of these changes make them different species.

      That's what I thought too, but then I actually looked it up and found the GP is actually right. Two groups of animals can be morphologically the same, but still considered different species due to natural inhibitions against interbreeding.

  3. excellent! by arekin · · Score: 4, Funny

    Now if only humans would evolve that fast...

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    1. Re:excellent! by foreverdisillusioned · · Score: 3, Interesting

      Err, that's nothing to do with the evolution of sexual desire, that's only because we've become so incredibly good at making cheap food. Haven't you ever seen those stone fertility idols? Or heard of societies where obesity is/was a sign of the aristocracy? People have gotten extra sex because they were fat for far longer than they've been denied reproductive opportunities for the same.

  4. Does this mean by NEDHead · · Score: 5, Funny

    If I keep on smacking my kids, their arms will get shorter?

    1. Re:Does this mean by pecosdave · · Score: 4, Funny

      Their skulls may become thicker.

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  5. You're Welcome by Anonymous Coward · · Score: 5, Funny

    ...And this is yet another proof that God exists. My prayer circle has spent the last 10 years asking for Divine intervention to halt the senseless deaths of road-adjacent animals. Thanks to our unceasing intervention, He knew to trim a wee bit off the tip of every bird's wings (gradually, of course, so that mommy birds would still recognize their babies - and left longer wings on the sinner birds so that they would die and serve as a warning to others). Praise Jesus!

    1. Re:You're Welcome by Anonymous Coward · · Score: 3, Funny

      That is a really tough story to... Swallow...

  6. lies, all lies by spongman · · Score: 4, Funny

    these evolutionists are just trying to force these lies down your throats.

    how can the birds be changed by the overpasses? the bible tells us that the overpasses have existed since the creation of the universe, 3 decades ago.

    1. Re:lies, all lies by Anubis+IV · · Score: 4, Insightful

      The funny thing, at least to me as a Christian, is that none of the other Christians I know would take issue with anything said in the summary, other than the use of "evolution" to describe natural selection and adaptation: principles with which they have no problems.

    2. Re:lies, all lies by X0563511 · · Score: 3, Insightful

      ... even though that's exactly what evolution is?

      I think they have a hard time understanding what the Theory of Evolution really is. If they did, they'd suddenly find it's compatible with faith as-is.

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    3. Re:lies, all lies by Anonymous Coward · · Score: 5, Informative

      http://www.gallup.com/poll/155003/hold-creationist-view-human-origins.aspx

      "Forty-six percent of Americans believe in the creationist view that God created humans in their present form at one time within the last 10,000 years. The prevalence of this creationist view of the origin of humans is essentially unchanged from 30 years ago, when Gallup first asked the question. About a third of Americans believe that humans evolved, but with God's guidance; 15% say humans evolved, but that God had no part in the process."

    4. Re:lies, all lies by LordLucless · · Score: 4, Interesting

      Evolution and abiogenesis are frequently conflated. Many Christians have no problem with the former, but do not agree with the latter.

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    5. Re:lies, all lies by Anubis+IV · · Score: 4, Insightful

      Hmm...yes and no. When people talk about "evolution", they're generally talking about the creation of new species via the combined mechanics of random mutation and natural selection. Natural selection is something that everyone I know is fine with. Random mutation is something that everyone I know is fine with. But the creation of new species? Not so much. And in this case, we're merely seeing natural selection at play, which is not evolution, in and of itself, any more than a motor by itself should be considered a car.

  7. Bridgekeeper by Anonymous Coward · · Score: 5, Funny

    What is the new air speed velocity of an unladen cliff swallow?

    1. Re:Bridgekeeper by pecosdave · · Score: 4, Funny

      The one impaled on the antenna of a passing vehicle or not?

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    2. Re:Bridgekeeper by Grayhand · · Score: 4, Funny

      The one impaled on the antenna of a passing vehicle or not?

      I don't know but the little fucker dropped his coconut and cracked my windshield.

  8. Maybe birds with shorter wings don't fly as much by Leuf · · Score: 4, Interesting

    The article says it's because they are more maneuverable, but what if they just sit on their asses a lot unlike their easier flying longer winged relatives? Fly less, get hit less.

  9. Saw a Chipmunk Up In the Mountains by Greyfox · · Score: 5, Interesting

    I was driving up in the mountains a year or so ago and saw a chipmunk run out into the road between me and the car coming the other way. Now normally this is pretty much certain doom for the chipmunk, but this one stopped calmly on the yellow line, stood up and waited for us to pass before continuing. I've always wondered if the evolutionary pressure of traffic combined with their short generation cycles would lead to critters less likely to become roadkill. Guess I have my answer.

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    1. Re:Saw a Chipmunk Up In the Mountains by DigiShaman · · Score: 5, Informative

      Squirrels. They used to zig-zag back and forth (can't make up their mind) and get crushed. Now, they either wait patiently or bolt across the road when everything looked all in the clear.

      But yes, it would seem the indecisive critters got weeded out.

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  10. Re:not evolution by Nadaka · · Score: 3, Insightful

    The definition of evolution existed for over century before genetic material was discovered.

    Keep changing the goalpost because the facts don't match your dogma, kinda like "climate change"

  11. Evolution? Maybe... by camperdave · · Score: 5, Insightful

    Yes, this may be due to evolution, not of the birds, but the automobile.

    To generate increased fuel economy, today's automobile is a lot more streamlined than ones of the past. So there is less air disturbance. It may be that the birds with smaller wings are not affected by the turbulence as much as the larger winged birds are now, and can thus survive an encounter, whereas in the past, there was enough turbulence to affect the birds regardless of wingspan. Also, changes in traffic patterns and vehicle types changes the exhaust, which changes the local plant life, which changes the insect life, which ultimately changes the birds.

    While it is simple to observe that long winged birds are being disproportionately killed and that the population's wingspan is growing shorter, and conclude that some sort of selection (Is it natural selection when birds are hit by cars?) is taking place, the reality may be quite different.

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    1. Re:Evolution? Maybe... by Vreejack · · Score: 3, Insightful

      Um, what? Are you trying to suggest that bird wings are shrinking because automobiles produce less turbulence than they used to?

      I have seen some really stupid write-ups in Science, but this one was concise and accurate. Roadkill birds have longer wings and the average wingspan has decreased over the decades of the study. It is known that birds with shorter wingspans are more agile in the air. The conclusion is that roadkills are placing a selection pressure on the birds for shorter wingspans. Turbulence is not actually believed to play much of a part, as death is caused when the birds are struck by cars, not when they get caught in their wake.

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    2. Re:Evolution? Maybe... by camperdave · · Score: 3, Interesting

      Um, what? Are you trying to suggest that bird wings are shrinking because automobiles produce less turbulence than they used to?

      No, I am suggesting that bird wings are shrinking because the automobiles are using a different blend of fuel than they used to.

      Further, I am suggesting that turbulence inducing vehicles might be harder to avoid. The wake could cause a bird to hit the side or rear of a vehicle, or whip it into the ground, or just be violent enough to snap the wing altogether without the bird even hitting anything. Who knows? If the types and sizes of vehicles, the frequency and distribution of traffic, and even the fuel composition of the vehicles travelling through the underpass were the same, then the conclusion would have been a slam-dunk. However, the traffic now is not the same as it was thirty years ago, so there is another variable in the scenario; a variable that could cause the same observed phenomenon (unlikely though it may be).

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  12. Kinda Related... by SuperCharlie · · Score: 5, Interesting

    I had to go through a set of lights by a couple truck stops back in the day more than once a week. I noticed grackles (crowish kinda birds) that would wait on the posts or nearby for the lights to turn red. Then they would jump down and pick the grasshoppers and bugs out of the 18 wheeler grills. When the light turned green, they all flew back up and waited. They were quite well fed.

  13. Re:How come no animals have evolved 4D by Zordak · · Score: 3, Interesting

    I'd say that the Book of Genesis was part of Christian tradition, and that explicitly states that God created animals and man from scratch, in direct contradiction to the Theory of Evolution.

    What Bible are you reading? From Genesis 1:

    11 And God said, Let the earth bring forth grass, the herb yielding seed, and the fruit tree yielding fruit after his kind, whose seed is in itself, upon the earth: and it was so.

    12 And the earth abrought forth grass, and herb yielding seed after his kind, and the tree yielding fruit, whose seed was in itself, after his kind: and God saw that it was good.

    I'm missing the part where it "explicitly" says "from scratch with no evolution involved." It just says God said, "Make it so," all Captain Picard like, and then it was carried out through some unspecified agency.There are literally no details about how it was done. Likewise with the animals:

    20 And God said, Let the waters bring forth abundantly the moving creature that hath life, and fowl that may fly above the earth in the open firmament of heaven.

    21 And God created great whales, and every living creature that moveth, which the waters brought forth abundantly, after their kind, and every winged fowl after his kind: and God saw that it was good.

    22 And God blessed them, saying, Be fruitful, and multiply, and fill the waters in the seas, and let fowl multiply in the earth.

    23 And the evening and the morning were the fifth day.

    24 And God said, Let the earth bring forth the living creature after his kind, cattle, and creeping thing, and beast of the earth after his kind: and it was so.

    25 And God made the beast of the earth after his kind, and cattle after their kind, and every thing that creepeth upon the earth after his kind: and God saw that it was good.

    Even the word "day" could better be rendered "time period." A "day" might be 1 billion years. In any case, evolutionary theory neither proves nor disproves God. In fact, if you read Origin of Species, you'll find that Charles Darwin was not the atheist demigod smarmy atheists like to make him out to be. He speaks quite openly about God and pontificates that "Hey, maybe this is how God speciates animals." (Also, he wasn't particularly concerned with the ultimate origin of life. He was specifically concerned with speciation.)

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  14. Re:How come no animals have evolved 4D by gsslay · · Score: 4, Insightful

    A "day" might be 1 billion years.

    And "seed" might be asteroids, "fowl" might be spaceships, "creeping thing" might be nanotech bots and "blessed" may be "provided a 1 billion year support contract". If you like to provide your own translation of every word and concept in the Bible, you can make it anything you want it to be, prove anything you like and be infinitely update-able.

    If we were to accept this, it must be very comforting that Genesis can seem to be more than simplistic myth. But it doesn't stop it being fiction.

  15. Re:How come no animals have evolved 4D by yurtinus · · Score: 3, Insightful

    I'm pretty sure any non-idiotic *anybody* simply says the Bible is a collection of stories and parables with valuable life lessons for the place and time in which it was written. As with all old stories, they're usually rooted in some factual event that occurred at the time. Christians take it a step further claiming its writing was guided by God. Idiotic Christians take it even one step further claiming every word as a literal truth, but luckily there are very few of those.

    I know it's fashionable to assume everybody who believes in Christianity takes every kernel of the Bible as an absolute truth, but most take the book as a whole. You talk about ignoring the details - with all of our modern science, we *still* can't grasp the details of how the universe was created.

    Hell, I'm not even a Christian. Why do you jump to inflammatory conclusions and make me take their side?

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