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Chickens, 2012

The views expressed are those of the author and are not necessarily those of Scientific American.


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I spend a lot of time looking at chickens. Try looking at them yourself. They’re incredible.

You've heard of combs and wattles. That flap posterior to the cheek region is called an ear lobe.

Transylvanian naked-necked chicken, photo by Lily15.

I don’t want to say too much about chickens as I’ll be here all day (drat, semi-failed). Must say a few brief things though. The history of chicken domestication is complex (though the Red junglefowl Gallus gallus is the primary progenitor), as is the story of how people took chickens (from a centre of origin in or near south-east Asia, perhaps in Thailand) west to Asia Minor, Europe and Africa, as well as east across the Pacific. Some Asian chicken breeds (often used primarily as fighters) were and are gigantic and strikingly long-legged, and some people have suggested that a now extinct, mysterious giant species or form of chicken – dubbed Gallus giganteus – contributed to the domestic chicken gene pool. By crossing several large Asian breeds, the American Jersey giant was created – a breed where cocks can weigh about 6 kg. Debate continues over whether Polynesians took chickens to South America prior to the time of Columbus. Polynesian chickens had key roles in entertainment (fighting) and ornamentation (on Hawaii, their feathers were used to indicate the sovereignty of kings on decorative poles termed kahilis) as well as in providing edible protein.

People have bred featherless – yes, naked – chickens, and there’s also a highly distinctive Romanian breed (sometimes unofficially dubbed a turken or churkey on account of a vague similarity with turkeys) with a naked neck. Japanese Yokohama cocks can have tail feathers measuring anything up to 10.6 m (this is the record-holder, reported in 1972 from Shikoku). Silkies are famously weird in having hair-like plumage (rendering them flightless) as well as five toes on each foot and blueish-blackish skin, flesh and bones. Black meat and bones are also present in the Indian Kadaknath and Indonesian Ayam Cemani. Birds in general typically possess white or black skin, yet many domestic chicken breeds have yellow skin. There’s a ton more that could be said, but consider this a teaser.

And, finally, for those who have never seen it before…

The accompanying paper (available as a free pdf) is available here. For more on gamebirds at Tet Zoo, see…

Darren Naish About the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at darrennaish.wordpress.com. He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at tetzoo.com! Follow on Twitter @TetZoo.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. Hai~Ren 6:44 am 04/12/2012

    In Chinese cuisine, ‘black chicken’ (probably Silkie or some other breed with similar black-tinged skin, flesh, and bones) is usually cooked in herbal soups and tonics, and is believed to have some sort of medicinal value lacking in typical domestic chickens. (Supposedly carnosine)

    I live in a part of the world where wild red junglefowl (or in some areas, possible first-generation hybrids between red junglefowl and domestic chickens) are not uncommonly encountered in some of our parks, and even in suburban neighbourhoods close to forest and secondary scrub. For the urbanites who tag along on my guided walks, it’s always quite surprising to see ‘chickens’ in the forest.

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  2. 2. SRPlant 7:08 am 04/12/2012

    I often see a race of naked-necked chicken here in Burgundy, France. Presumably it’s a temperature regulation adaptation to help the birds cope with the baking heat of the courtyard after soaring at great heights.

    BTW I’ve just been reading about a feral chicken population in Los Angeles (i.e. at the Burbank turn-off) on Wiki. I wondered why there weren’t more feral populations in the western world – maybe there are…

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  3. 3. llewelly 8:08 am 04/12/2012

    ” Debate continues over whether Polynesians took chickens to South America prior to the time of Columbus. ”

    Has any genetic analysis been done?

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  4. 4. Christopher Taylor 8:20 am 04/12/2012

    Some Asian chicken breeds (often used primarily as fighters) were and are gigantic and strikingly long-legged

    Case in point. Malays can apparently reach a little shy of three feet in height.

    there’s also a highly distinctive Romanian breed with a naked neck
    Apparently the so-called ‘Transsylvanian naked-neck’ really came from Hungary.

    People have bred featherless – yes, naked – chickens
    But is there any truth to the persistent rumour that the proprietors of KFC have bred a chicken with four drumsticks?

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  5. 5. llewelly 8:29 am 04/12/2012

    SRPlant, here’s an article about a related population:
    http://en.wikipedia.org/wiki/Hollywood_Freeway_chickens

    (thanks to Heteromeles; it was linked off of the Reggie the Alligator article.)

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  6. 6. naishd 8:33 am 04/12/2012

    llewelly (comment 3): yes, DNA work has been done. Initial results supported affinity between an ancient Chilean chicken and those from Asia/Polynesia, later analysis seemed to show that the Chilean bird came from Europe (that is, its ancestors were transported across the Atlantic). I’ll compile the refs later – there has been an to-ing and fro-ing about this issue in PNAS. Two of the key papers are…

    Storey, A. A., Ramírez, J. M., Quiroz, D., Burley, D. V., Addison, D. J., Walter, R., Anderson, A. J., Hunt, T. L., Athens, J. S., Huynen, L. & Matisoo-Smith, E. A. 2007. Radiocarbon and DNA evidence for a pre-Columbian introduction of Polynesian chickens to Chile. Proceedings of the National Academy of Sciences 104, 10335–10339.

    Gongora, J., Rawlence, N.J., Mobegi, V.A., Jianlin, H., Alcalde, J.A., Matus, J.T., Hanotte, O., Moran, C., Austin, J.J., Ulm, S., Anderson, A.J., Larson, G. & Cooper, A. 2008. Indo-European and Asian origins for Chilean and Pacific chickens revealed by mtDNA. Proceedings of the National Academy of Sciences 105, 10308-10313.

    Chris (comment 4): Transylvania was part of Hungary until after WWI, so saying that Transylvanian animals “came from Hungary” is perhaps misled by the fact that Transylvania itself has ‘changed countries’. This is still a slightly sensitive topic in Transylvania (I was there last year).

    Darren

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  7. 7. SRPlant 8:48 am 04/12/2012

    Thank you, llewelly.
    “The Hollywood Freeway chickens are a colony of feral chickens that live under the Vineland Avenue off-ramp of the Hollywood Freeway”
    You couldn’t make it up.

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  8. 8. llewelly 9:28 am 04/12/2012

    Old joke:

    Once there was a man, driving down a lonely country road. After a time, he noticed a chicken running alongside the road, matching pace with his car. And there was something strange about this chicken, but he couldn’t quite put his finger on it. The man looked down at his speedometer and saw that he was doing about 40 mph. “Wow” he thought, “that’s a fast chicken”. So he decided to see how fast this bird could go. Gradually he increased speed, up to about 60 mph. The chicken kept pace with him all the way. The man shook his head in amazement. Then he stomped on the gas, and sped up to 90 mph. Unbelievably, the chicken put on a burst of speed, and not only kept with the car, but pulled ahead, and left the car in its dust.

    But when the chicken had pulled ahead, the man noticed something: It had four legs.

    Far down the road, he saw the chicken turn and run into a farm. When he got to the farm, he saw a farmer outside, so he pulled up, got out, and said:

    “You might not believe this, but I saw a four-legged chicken running along the road, and it out ran my car, even at 90 mph. It ran into your farm.”

    “Ayup”, said the man, “that’s one of ourn.”

    “Wow. Where did you get a four-legged chicken?”

    “We love drumsticks around here, so we bred ‘em special, so’s we’d have more to go around.”

    “Really? How do they taste?”

    “Dunno. Never caught one yet.”

    My grandfather claimed to have heard a version of this joke as a child. I’ve heard it told for 3 legged and six legged chickens as well, and there’s an alternate ending, which I can’t recall, involving a KFC factory farm.

    I suspect, but can’t prove, this is the origin of the rumors that KFC has bred four legged chickens.

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  9. 9. Heteromeles 10:42 am 04/12/2012

    What’s to make up? Those LA chicks are tough. And smart.

    I grew up in the LA hills, and one year, we ended up with a “rescue” chicken, a large black hen, after a brush fire. She’d apparently been in Topanga, ran away from the fire, crossing about 10 miles of chaparral with at least one other bird (a hiker found the remains of another black hen in the hills). She lived with us for years, chasing rats out of her coop, yelling for the dog when a coyote showed up outside the fence, and “naming” the bugs that my mom dug up as she weeded the garden. Her “names” were clucked variations on the theme of “yum” and “yuck,” but she had a different name for each bug type, and she’d comment on them before she ate the ones named “yum.”

    On a different topic, as I recall, there was some interesting thoughts about chickens in the NOVA “Rat attack” episode (http://www.pbs.org/wgbh/nova/nature/rat-attack.html). If I remember rightly, both chickens and (Norway) rats were proposed to have co-evolved with bamboo, in the sense that they could reproduce explosively to take advantage of a bamboo mass fruiting. This trait was supposed to make them useful (in the case of chickens) or dangerous (in the case of rats). Is this generally accepted?

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  10. 10. naishd 10:55 am 04/12/2012

    Neat anecdotes, Heteromeles. There are many tales of bold, plucky chickens that have fought off (and even killed) rats, foxes and other predators. But, then, if you’ve ever been attacked by an angry cock, nothin’ will surprise. A Californian game cock with knives attached to its spurs killed a man last year by cutting his throat.

    Hens teach their chicks which food items are acceptable and which are not by titbitting/tidbitting – tossing bits of the food in the direction of the chick(s) while making a special feeding call (though some titbitting is done silently). And there has long been debate and interest over whether the different vocal signals used by chickens have different meanings. I think it’s pretty obvious that they do.

    The bamboo thing is new to me.

    Darren

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  11. 11. Zoovolunteer 11:36 am 04/12/2012

    I am not sure if chickens have distinct calls for different food types but it would not surprise me. I attended a lecture once by someone who kept Cheer pheasants Catreus walichii and they had distinct alarm calls for terrestrial and avian threats. I suspect most if not all social animals have calls which define specific threats or opportunities in the environment.

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  12. 12. Jerzy Again 5:14 pm 04/12/2012

    I see this is evolving into a new type of an entry: Darren supplies an animal and we make a story about it themselves. ;)

    So, my turn: in Sri Lanka, there is even more beautiful Sri Lanka Junglefowl. It doesn’t hybridize with free-roaming domestic chicken, one reason is that male doesn’t crow but produces metalic hink-honk remarkably like a call of Bearded Bellbird from Venezuela.

    Anybody knows of other examples where two animals from totally different places have very similar call?

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  13. 13. Heteromeles 5:29 pm 04/12/2012

    Make up? Um, no, I actually got to see that Black hen do all those things. At the time, I didn’t think chickens were very intelligent, and I learned a lot from her.

    Besides, it doesn’t take a huge intelligence to name foods as yummy, meh, wow, yuck, eww, ooo, and so on. Household pets will do pretty much the same, just by differential begging behaviors. Try giving a cat a parsley garnish when it’s begging for the tuna on your plate, and you’ll see the cat’s “name” for parsley quite clearly, if only in body language.

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  14. 14. Christopher Taylor 7:18 pm 04/12/2012

    Anybody knows of other examples where two animals from totally different places have very similar call?

    See:

    Henry, C. S., M. L. Martínez Wells & C. M. Simon. 1999. Convergent evolution of courtship songs among cryptic species of the carnea group of green lacewings (Neuroptera: Chrysopidae: Chrysoperla). Evolution 53: 1165-1179.

    In the lacewings studied, species from China and North America had identical mating calls. The authors suggested that such convergence would be more likely among geographically separated species because there would be no selection pressure to keep them divergent.

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  15. 15. Mark Robinson 3:37 am 04/13/2012

    When I was a kid we had a Chinese Silky rooster with 6 toes on one foot and 7 on the other. One toe on each foot was basically just a claw but the others looked like proper toes.

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  16. 16. John Harshman 12:14 pm 04/13/2012

    I recall a talk a few years ago at an AOU meeting (I think; could have been Evolution) to the effect that there are no remaining wild populations of red junglefowl that don’t have strong introgression from domestic chickens. One genetic trait of interest was the willingness to be held in the hand without struggling, most interesting because it was easy to assay. And it was widespread in “wild” populations.

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  17. 17. David Marjanović 9:19 am 04/14/2012

    Presumably it’s a temperature regulation adaptation to help the birds cope with the baking heat of the courtyard after soaring at great heights.

    …Soaring?

    Chickens?

    Case in point.

    Isn’t that actually normal for adult chickens? The fully ossified skeleton in the paleontology teaching collection of the University of Vienna looks like that.

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  18. 18. naishd 5:59 am 04/15/2012

    David (commment 17): it’s the temperatures that were described as soaring to great heights, not the chickens.

    Long-leggedness and height in domestic chickens: you might be being fooled by the fact that all chickens look samey as skeletons, with (of course) long necks and long legs. However, in living form, many breeds (certainly those typically farmed in the west) have so much bulk in the body and so much feathering that they certainly don’t exhibit this gracile, very leggy appearance. Instead, it’s special to fighting breeds like the various aseels (or asils).

    Darren

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  19. 19. David Marjanović 7:58 am 04/15/2012

    I was talking about the height and, well, the length of the skeletal legs. I’m a paleontologist, I don’t care about soft tissue all that much ;-)

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  20. 20. naishd 8:33 am 04/15/2012

    “I’m a paleontologist, I don’t care about soft tissue all that much”

    Herein lies part of the reason why palaeontologists are typically so terrible at providing advice on restoring the life appearance of fossil animals :) I’ve given up telling dinosaur palaeontologists about the musculature that extends along the anterior face of the tibia in dinosaurs.

    Darren

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  21. 21. SRPlant 9:58 am 04/15/2012

    Re “soaring”; Unfortunately David M’s suspicions were correct. I was making facetious reference to bare-necked vultures. I blame Gary Larson.

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  22. 22. Hai~Ren 10:08 am 04/15/2012

    I happened to hear (and glimpse) a red junglefowl cock yesterday. One of the identifying features that local birders use to distinguish red junglefowl from domestic fowl is that the red junglefowl’s crowing ends abruptly, like it got strangled, instead of a domestic rooster, which tends to drag out the final note. It’s interesting that domestic chickens would sound different from their wild relatives; it’s almost like how domestic dogs bark, unlike wolves or dingoes. I wonder if such difference in vocalisations comes about due to subtle changes in anatomy.

    Also, what I’ve noticed is that in domestic chickens, hens possess a comb and wattles, which are absent in hens of red junglefowl. I wonder what happened during domestication that led to females taking on such masculine traits.

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  23. 23. Heteromeles 10:53 am 04/15/2012

    @Hai-Ren: how does the behavior of female chickens differ from the behavior of female jungle fowl? If hens are more “masculinized” in their behavior, in a way that favors their domestication (perhaps being bolder around humans than their wild counterparts are) that might explain it.

    As for the longer crow of a rooster, that’s fascinating. It would be fun if someone runs a domestication experiment on wild fowl similar to the Russian fox experiment, so that we could see whether such changes arise spontaneously as a result of selection for docility around humans.

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  24. 24. Christopher Taylor 1:00 am 04/16/2012

    Isn’t that actually normal for adult chickens?

    Unfortunately, I couldn’t find a good photo of one of the really big Malay cocks that contained a really good indication of scale, which is why I also referred to the maximum height. Take my word for it, they are absolute monsters.

    That said, not all the giant chicken breeds are Asian game cocks. According to this page, the largest breed is the Jersey Giant, with hens about 4.6 kg in weight. In contrast, a Malay hen is about 3.2 kg (but, being so leggy, their apparent size would belie their actual weight). Jersey Giants are apparently not very common because they are simply too big to be economical (they take too long to grow to maturity).

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  25. 25. naishd 5:53 am 04/16/2012

    Thanks for that, Chris. Just want to note that the article above specifically refers to Jersey giants.

    Darren

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  26. 26. Hai~Ren 9:21 am 04/16/2012

    Heteromeles: Behaviourally, hens of red junglefowl are pretty much the same as domestic hens (besides being more shy of humans, and having no problems flying). You can view short videos of red junglefowl hens at the following YouTube links: http://youtu.be/MVa90VQAm6g http://youtu.be/Yfy9-xUaTZQ Note the lack of any comb or wattles.

    You can hear examples of the ‘strangled’ crowing of the red junglefowl rooster at Xeno Canto, and in these YouTube videos: http://youtu.be/IrxkL2ICqfs http://youtu.be/RdyS4ngyN2s

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  27. 27. David Marjanović 2:49 pm 04/16/2012

    Herein lies part of the reason why palaeontologists are typically so terrible at providing advice on restoring the life appearance of fossil animals :-)

    Bingo!

    Now please stop me before I rant about the term “rodlike stapes” and tympanic ears.

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  28. 28. HowardRichards 2:59 pm 05/6/2012

    The existence of “Chinese” breeds of chicken in South America was one piece of evidence used in “1421: The Year China Discovered America”. (I know, I know. If he had just said some Chinese ships may have reached the Cape of Good Hope, I’d have said, sure, maybe. If he had said some Chinese ships may have touched the New World, I’d have said that it was technically feasible. But what he did say was painful to read — the Chinese apparently fundamentally revolutionized basic aspects of life in the Americas, but were somehow totally forgotten by the time Europeans arrived: less than a century later.)

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