Wonderful Life: The birds of paradise

September 20, 2014 • 12:02 pm

The Cornell Laboratory of Ornithology has completed its Birds-of-Paradise Project, a veritable paradise for bird aficionados, nature lovers, and especially professors like me who want to show students the most stunning examples of sexual selection on Earth. (Remember that sexual selection is just a form of natural selection: a subset of that phenomenon that rests on differential mate choice.)

You can read about the project’s aims here, but the site is huge and interactive: you can hear and see the birds, and read about their evolution and natural history (there are 39 species on New Guinea, the surrounding islands and [a few in] Australia). Best of all are the fantastic videos: a ton of them, and they’ve put them on YouTube. I’ll show just the introductory video, which displays many of the species, and then a few others. They’ve managed to film all of them, so that will whet your appetite for more.

Evolution educators: this is a site you shouldn’t miss.  Their words:

It took 8 years and 18 expeditions to New Guinea, Australia, and nearby islands, but Cornell Lab scientist Ed Scholes and National Geographic photographer Tim Laman succeeded in capturing images of all 39 species in the bird-of-paradise family for the first time ever. This video gives a sense of their monumental undertaking and the spectacular footage that resulted.

Here are all 39 species:

Carola’s Parotia (Parotia carolae), the “King of the Dance.” Don’t miss this one!

The dance of the Carola’s Parotia is the most complex of all birds-of-paradise. The male has to go through five introductory dance moves before starting the main event, called the “ballerina dance.” All the while, four or five females may be perched above him, examining every detail of his performance before deciding whether to mate.

Imagine sexual selection accumulating genes that make the male do this, with all components of that behavior contributing to the male’s chances of leaving those genes.

The Male Riflebird (Ptiloris victoriae), with a directional iridescence:

Iridescence can be seen only when light hits feathers at just the right angle. By adjusting where they are relative to their audience, males can “turn on” their bright colors. Magnificent Riflebirds seem to use this feature with particular precision, even choosing display sites that put their audience in exactly the right place to see the show in the best light.

Finally, one of my favorite, the King-of-Saxony bird of paradise (Pteridophora alberti), with its amazing cull and impressive head feathers:

Throughout their evolution, male birds-of-paradise have been under immense selective pressure to win the attentions of females. Even the King-of-Saxony’s extraordinary head wires aren’t quite enough. They’ve had to develop a display that includes waving the head plumes, rhythmically bouncing on a perch, and delivering an extraordinary screeching, buzzing, hissing call that sounds like anything but a bird.

Note that only the males have the elaborate colors, plumage, and behaviors: females are generally inconspicuous and dull-colored. That’s one of the observations, consistent among many animals, that led Darwin to propose the theory of sexual selection (1871). Sadly, Darwin never saw these species, as the H.M.S. Beagle didn’t visit New Guinea. Here’s the relevant part of the voyage:


There are many more videos. Knock yourself out!

As for why this particular group of birds was so prone to forming new species—and with speciation probably based on differential sexual selection—who knows?

h/t: Gunnar

25 thoughts on “Wonderful Life: The birds of paradise

  1. I’m thinking part of it is going to have to be an easy lifestyle — abundant food, few predators. First, it’s the only way they’d have the spare resources to devote to this sort of thing rather than just eating and avoiding being eaten. Second…in such an easy environment, there’d be a real danger of a population explosion and crash, unless there was something that kept populations in check. This sort of extravagance is expensive in such a way, I would think.


    1. Your second point sounds like you’re saying that elaborate courtship displays are a way for individual birds to limit their own fertility for the good of the species. Obviously you know that natural selection doesn’t give a hoot about that, so I must be misunderstanding you somehow.

      1. Well, there’s got to be some sort of evolutionary pressure on fecundity, no?

        A species that breeds like…well…rabbits will quickly go downhill due to disease and food exhaustion and all the other maladies of overpopulation unless there’s significant predation to keep the population in check. A species that doesn’t reproduce enough to replace the breeding population goes extinct. One way or another, that balance has to be struck or else the species as an whole is going to succumb.

        So, what are the evolutionary pressures that drive rabbits towards fecundity and, say, many birds that will lay and fledge at most one or two chicks per year?


        1. Why does a balance have to be struck? Boom-and-bust population cycles happen all the time in nature, and species sometimes go extinct as a result. Equilibrium is not an ecological requirement.

          It still sounds like you’re arguing for some sort of foresightful group selection that sees disaster coming and acts to preserve the species. But I know you know it doesn’t work that way. If birds invest a lot in a few offspring, it’s because it’s advantageous to those individual birds to do so, not because they’re conscientiously practicing ZPG for the benefit of future generations.

          (If you want me to guess about the different selection pressures on rabbits and birds, my guess is that it’s like the difference between getting a driver’s license and getting a pilot’s license. The latter takes a whole lot more individualized attention from the instructor.)

          1. Put it this way: a species whose population is stable over the long term is, I would think, be more likely to survive into deep time than one subject to crashes or below-replacement declines. Whatever the mechanism by which effective population regulation methods arise, I’d expect more species to have them than not. And, indeed, that’s basically what we see: environments with significant predator and prey dynamics, such as the African savannah, have prey that breed like rabbits and predators that turn on each other when populations get above a certain size. With these and similar birds not subject to significant predation and with abundant food, mate selection is incredibly picky.

            Are the individuals in any way aware of the reasons for why their reproductive habits are what they are? Almost certainly not. Rabbits bereft of predators still breed profusely, and I don’t think the female birds of paradise would be significantly less picky if they were the last of their species living in a zoo.

            But, left to the environments which they evolved in, their respective breeding strategies generally result in long-term stable populations. In different environments, those same strategies may well be disastrous, and different strategies in their own environments would likely also be disastrous.


            1. So you are endorsing group selection then. You’re saying there’s a selection mechanism operating at the species level that somehow overrides individual reproductive advantage in order to stabilize populations.

              But that’s not what we see. What we see is that the vast majority of species are transient and do not survive into deep time. Lineages survive by evolving into new species, and genes survive by ruthlessly maximizing the number of adult bodies they inhabit. You have yet to show how a gene for population stability accomplishes that.

  2. May I also draw your attention to the Superb Lyrebird of Australia. Whilst it’s not a bird of paradise, it does share the ornate plumage and elaborate courtship behaviour which characterises that group.

    The Superb Lyrebird is remarkable in that its courtship display involves mimicking the calls of other species. The range and accuracy of its mimicry is quite astonishing, and it includes man-made sounds in its repertoire. Words alone don’t do justice, so here is a YouTube clip from an episode of the 1998 BBC television series “The Life of Birds” presented by David Attenborough, in which a Superb Lyrebird mimics a kookaburra, a camera shutter, a car alarm and a chainsaw:

      1. The chainsaw impersonation is truly impressive, with all the crashing branch sounds added in. Rather sad, though, for what it implies about what’s happening to this bird’s environment.
        What a truly stupendous creature!

  3. The entry on the birds of paradise in Wikipedia describes that they belong to the same family, and are divided into several related genera within that family. A few other spectacular species in the region were once considered birds of paradise as well, but they have since been put into other families. What remains is still an interesting problem for evolution. How did several closely related species evolve within a fairly contiguous range with striking differences in sexual selection? That they are closely related is reported by findings of hybrids between several of the species.
    There could be fine differences in habitat (as in different levels of the forest, different kinds of forest, separation by mountain peaks). Differences in diet might also direct different routes of sexual selection, although this seems challenging since they all seem to eat fruits and insects.

    Anyway, an interesting problem!

    1. Rather parallel to the situation of many Dendrobatid (if they haven’t since changed the taxonomy) frogs in the American tropics.

        1. Well, actually I was thinking color morphs. And come to think of it, I may be thinking of variation at the population level, not the species. I’ll have to revisit this.

          Yes, indeed, different morphs maintained w/in Oophaga pumilio. My bad. Still a very cool story, though, hypothesized, last I heard, to be maintained though sexual selection.

  4. Amazing! I just watched all these videos. I’ve always found birds of paradise fascinating and spectacular…thank you so much for posting this.
    It’s a good thing human females aren’t so picky – or are we?

    1. Thinking about it, as per Ben’s point above about environment and conditions – with improved opportunities and a changed social environment, more female humans over time can afford to be more picky.

  5. Amazing male bird testosterone-vibe appealing to the female bird estrogen-vibe. 🙂 What a wonderful project and website and enjoyed the videos! Thanks for redirecting back to these.

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