Readers’ wildlife photos

We have a post-Thanksgiving treat today: reader and evolutionary ecologist Bruce Lyon has sent some great photos and information about turkeys and their dancing relatives. His notes are indented.

Many of us have a culinary appreciation for turkey—I thought it would be nice to increase biological appreciation as well by presenting a bit about the behavior of the bird we eat, at least for its wild relative, the Wild Turkey (Meleagris gallopavo). And, while I am at it, I will also describe a couple of other interesting species in the taxonomic order in which turkeys reside, the Galliformes.

One of the more interesting aspects of turkey behavior is their mating system. Males display to females in groups. Below, a photo of two males displaying together (unattributed photo from the web)

A striking part of this group display is that the same males always display together—might these displays be a form of male cooperation? Groups of males are more successful at attracting females (and copulations) than are solitary males—by quite a margin. Paradoxically, the males in each group have a clear dominance hierarchy, and only the single most dominant male ever gets to copulate with the females.

This raises the obvious question: why on earth would the losers participate in a cooperative display, since they help increase the mating success of the dominant male but gain no direct benefit themselves because they don’t get to mate? It turns out that groups are composed of close relatives—subordinates are helping their close relatives, likely a brother, increase their mating success. Due to this discovery, the turkey mating system has become a textbook example of kin selection. With kin selection, an altruistic behavior like helping a relative obtain matings is favored because the subordinates enhance the success of identical copies of their same genes residing in a close relative. Just as parents favor copies of their genes by having babies, kin selection works through favoring genes found in close relatives. Some people consider having kids a special case of kin selection since our offspring are closely related to us.

The turkeys are an interesting example of kin selection because researcher Alan Krakauer (now at the University of California, Davis) was able to estimate the specific mating cost and benefit values needed to show that this altruism makes evolutionarily sense. Kin selection can be stated mathematically as Hamilton’s Rule, after William D. Hamilton who first fully developed kin selection theory. Hamilton’s Rule simply looks at the tradeoff between the direct Darwinian fitness that a helper loses by helping (in the turkey example it is giving up breeding on your own and losing your own offspring) compared to the indirect benefits gained by helping genes in a relative. The indirect benefit gained is the increased success of the helped relative scaled down by the degree of relatedness between helper and recipient (scaling by relatedness is a simple way to assess the probability that the genes in the helper also occur in the recipient).

Amazingly, Krakauer was able to estimate all of these parameters: what the helpers give up by helping, what the dominant male gains from being helped, and the average relatedness in groups. Putting it all together, Krakauer showed that helping leaves more gene copies than not helping and displaying alone. As far as I know, this is one of few studies that has been able to directly test Hamilton’s Rule. The conclusion—that helping pays—raises the question why everybody doesn’t help. It seems that some males may not have any relatives to help; without relatives to help, displaying alone would be the best option.

Below: I observed displaying turkeys a couple of times in Arizona. The southwest birds differ from wild turkeys elsewhere—their white-tipped tails in particular are distinctive. Here, a male struts his stuff at the Southwest Research Station near Portal Arizona. Note the gorgeous iridescence on the body feathers.

Below: Another male not displaying. Note the tuft of feathers, or ‘beard’, hanging from the center of the breast. Beard length and tip color is apparently a very good indicator of whether or not a male is older than two years. Males also have pretty large spurs on their legs which they presumably use in fights.

Another interesting feature is the ‘snood’, the erectile, fleshy protuberance on the forehead. According the Birds of Cornell species account, the “colors and extension of the snood change rapidly with mood”. After fights, the loser apparently retracts its snood.

Below. What a face! Lots of colorful bare skin and wattles, also referred to as ‘carunculated’. Sexual selection produces some pretty crazy traits. Some accounts claim that these colors change during the display.

There is a second species of turkey, the Ocellated Turkey (Meleagris ocellata), found in the Yucatan region of Mexico and adjacent Guatemala. The species is tame and often easily seen at the spectacular Mayan ruins at Tikal, Guatemala, where I photographed this bird. This species is quite different in appearance from its northern cousin: the naked powder-blue skin on the head and neck is decorated with conspicuous orange-red nodules and the tail is very different (see below). These nodules almost look like engorged ticks! I wonder if these birds suffer from tick infestations and whether females pay attention. On a different topic, there appears to be no evidence that Native Americans ever domesticated this species, even though it was regularly eaten. In contrast, Wild Turkeys have been domesticated for at least 1500 years and perhaps much longer.

Below: I don’t have photos of Ocellated Turkeys displaying so I pinched one from the web. The males have beautiful copper and blue eyespots (ocellations, hence the species name) on the tail feathers. I seem to recall from seeing the bird many times at Tikal that males often display in groups, like the Wild Turkey. (Photo by Gary Kramer).

Another species that has grouped male displays, the Sharp-tailed Grouse (Tympanuchus phasianellus), shown below at a ‘lek’ display site at one of my coot study wetlands in British Columbia. Lek is a Swedish word used to describe grouped male displays in birds (hard to find a clear translation for lek but ‘play’ comes up; perhaps a Swede can educate us). Lekking has evolved independently in various bird groups, including turkey and grouse relatives, hummingbirds, birds of paradise, manakins, and sandpipers, among others.

Biologists have long been interested in leks for a couple of reasons. In lekking species, males provide females only matings but no material benefits like food, territories or parental care. Given this, leks provide good study systems for trying to understand the genetic benefits females get from mating with particular males (good genes? sexy genes for sons?). Biologists have also been interesting in understanding the evolution of lekking as a mating system. Why display in groups? In leks, mating is often very highly skewed so that very few males get most of the matings. The ‘hotshot’ hypothesis for leks proposes that males group around the very sexy hotshots in the hopes of parasitizing some of the matings from the females attracted to the hotshots. The ‘hotspot’ hypothesis proposes that leks form in areas with high female traffic for reasons unrelated to mating: lek sites are just good areas where males can increase their encounter rate with females. Finally, displaying males might be more vulnerable to predation and there might be safety in numbers by displaying close to each other (this has been shown for lekking frogs).


Below: A male Sharp-tailed Grouse in a mating dance. In the dance, the male maintains a standing posture with his wings outstretched and tail upturned, he extends his head with the yellow eyebrow combs showing and exposes his sexy purple esophageal air sacs, and then very rapidly stamps his feet. The dancing males seem to vibrate across the prairie. Several accounts I read claim that this dance inspired some of the dances of Native Americans.

Below: Another dancer. The pose reminds me of a plane about to taxi down a runway.

Below: Dancing is social—when one male began dancing, others soon started dancing as well. We noticed an interesting pattern that may connect to this social inducement of dancing. We observed the lek using our Toyota Four Runner as a blind, and noticed that revving the engine seemed to cause the birds to start dancing after they had stopped. To make sure it was a real pattern we did a little experiment and the pattern seemed very clear—each rev induced dancing. Our guess is that the noise or vibrations from car revving somehow mimicked the noise or vibrations produced by the stamping feet. Instead of a real male starting a stamping episode, our car triggered the dance.

Below: The lek was not all peace and harmony: there were a fair number of threats and chases. Here two males face off and threaten each other.

Below. I did not get any videos of dancing but a video shows the dance better than still photos so below is a video from YouTube of grouse dancing at a lek. (Video filmed by daughter of Peder Stenslie in North Dakota).

 

22 Comments

  1. Andrea Kenner
    Posted November 25, 2018 at 7:50 am | Permalink

    You gotta have a wing man!

    Great photos!

  2. davidintoronto
    Posted November 25, 2018 at 8:09 am | Permalink

    Good post. The kin selection stuff was especially interesting.

  3. Randall Schenck
    Posted November 25, 2018 at 8:21 am | Permalink

    Wild turkeys were introduced in parts of the Midwest several years ago. The Pheasant and Quail population has gone down since in these areas and some speculate this was caused by the turkeys?

    • Posted November 25, 2018 at 8:29 am | Permalink

      Shouldn’t that be “re-introduced”? Turkeys were native in the Midwest. Pheasants were introduced from China, so it is a nice healthy change to see turkeys replacing them.

      • Randall Schenck
        Posted November 25, 2018 at 9:14 am | Permalink

        I cannot speak for earlier times but there were no turkeys in Iowa (southern Iowa) all the time I remember – from 1950 forward. It was the number one place for quail hunting in the 60s and 70s. The turkeys were brought in much later. I do not know for sure what caused the reduction in quail and pheasants but some have said the turkeys go after the nests of the other birds. I know that back in 30s and 40s, if you wanted to hunt Turkeys you went to Arkansas.

        If you say turkeys were in Iowa earlier, I would have to check it out. But health is a consideration for all the birds.

        • Posted November 25, 2018 at 10:13 am | Permalink

          Randall, turkeys were native throughout the midwest, with the possible exception of expanses of treeless open prairie (which might describe much of Iowa). They were eliminated in Wisconsin already by the 1870s.

          Non-native birds often cause unexpected problems for native ecosystems (see for example the damage done by starlings, causing the near-extinction of bluebirds). Generally speaking it is a good sign of ecological health if native species are returning to their former range. The loss of the pheasants is sad for pheasants but will likely have only a neutral or positive effect on ecosystem health.

          Having said that, the main reason for the decline of pheasants is today’s more ruthlessly efficient agriculture, which eliminates hedgerows needed for nesting and shelter. That is not good for anything wild. Especially in Iowa where there isn’t much undisturbed wild land.

          • Randall Schenck
            Posted November 25, 2018 at 10:35 am | Permalink

            Yes, and I am sure the demise of turkeys in this area was due to the introduction of people. However, when the DNR (humans) decide to reintroduce they sometimes do so without considering some of the negative side. Maximizing revenue from the licensing of hunters for their own existence comes to mind.

    • rickflick
      Posted November 25, 2018 at 10:06 am | Permalink

      The kin selection aspect reminds me of Dawkins’ emphasis on selection seen from the gene’s point of view. The helper turkey gets no benefit at all, but his genes, which are present in his kin, do.

  4. Posted November 25, 2018 at 8:25 am | Permalink

    Very interesting post, as usual.

    In some lekking manakin species, I think a particular perch in the lek is special. Males of some species participate in group displays, but as in turkeys, the same individual always does the mating. In these cases the theory is that the “wingmen” help because doing so give them a better chance of inheriting the sexy perch when the dominant male dies.

  5. Michdevilish
    Posted November 25, 2018 at 8:26 am | Permalink

    ‘Lekker’ in Afrikaans means pleasurable/candy/fun. Also ‘to lick’.

    • Michdevilish
      Posted November 25, 2018 at 8:27 am | Permalink

      Or ‘to leak’!

  6. Posted November 25, 2018 at 8:53 am | Permalink

    Deliciously wonderful cooperation.

  7. Posted November 25, 2018 at 9:08 am | Permalink

    Very interesting!

    I saw a funny tee shirt on Hamilton’s rule once. It said:

    “If r < C/B, don’t bother to ask”

  8. CAS
    Posted November 25, 2018 at 10:07 am | Permalink

    Thanks! Interesting information.

  9. Mark Sturtevant
    Posted November 25, 2018 at 11:06 am | Permalink

    Wonderful stuff! I had recently seen lekking in a group of turkeys near my home, but did not understand the underlying kin selection aspect of it.

  10. Joe Dickinson
    Posted November 25, 2018 at 12:39 pm | Permalink

    Very interesting (and nice photos). I had not heard of that example of kin selection.

  11. Mark R.
    Posted November 25, 2018 at 1:01 pm | Permalink

    Great post.

    Interesting that the Native Americans of the Yucatan/Guatemala region didn’t domesticate the Ocellated turkey. I do know that Mexican/Central American Natives did domesticate the Wild turkey (Meleagris gallopavo). Maybe the Ocellated were plentiful enough that they didn’t need to, or were more difficult to domesticate. Or maybe they taste bad…

  12. Nicolaas Stempels
    Posted November 25, 2018 at 1:08 pm | Permalink

    Never knew about turkeys cooperating in lekking, fascinating!
    And that Mayan Ocellated Turkey, never knew.
    A wonderful post with wonderful photos.

  13. danfromm
    Posted November 25, 2018 at 2:44 pm | Permalink

    Interesting. Birds aren’t the only creatures that lek. In particular, some maternal mouthbrooding cichlid fishes in the great lakes of East Africa lek. There have been quite a few studies of their behavior. If I recall correctly, the usual pattern is for a female to mate with more than one male.

  14. Posted November 25, 2018 at 3:31 pm | Permalink

    Fantastic birds!

  15. Posted November 25, 2018 at 8:46 pm | Permalink

    Thanks for a wonderful post, photos and all, Bruce!

  16. Posted November 26, 2018 at 12:08 pm | Permalink

    What’s the etymological connection between “Turkey” and “turkey”?


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