So how do they do it?
How if you're a bird do you become something else?
The obvious way to change your shape if you're a bird -- and this is what I think most people
assume is what's going on when you see one of these shape shifters do its transformation
for the first time — is use your wings.
I mean that's the thing that - I think our brains look at the birds and we think, oh,
they're going to make some unusual shape.
It's because they’re lifting out their wings and they’re wrapping it around their head
or they're doing something with their wings.
And in fact some of the birds that are the shape shifting birds-of-paradise, the ones
that transforms themselves — mainly the riflebirds — that's what they use.
But their wings aren't like normal wings.
All the flight feathers are rounded instead of being pointy like they typically are for
flight, so the feathers look different.
And that's how they make this really nice, kind of perfect oval shape, or ovoid shape.
But the other species, they are using not their wings, so they're not using an appendage
but they're using a series of feathers that line their bodies, the same kind of feathers
that all birds have in terms of where they're found on the body.
And they're lining them up into precise ways to create this meta-structure, if you will,
that's a composite of all these little individual parts, all those little individual feathers.
So they're using those special muscles in the skin, lifting them out precisely, putting
them in to the place they need to line up and look like this unusual form.
So it's easy for us to think about how you might do that with your arms, your appendages.
But it's really hard for us to think about how you would do that with your feathers.
We don't have any analog, it would be like trying to figure out, you know, create a Mohawk
without hairspray, basically (laughs).
By this you mean using the muscles in the head.
Using the muscles in your hair.
That's right.
Yeah, the same muscles that we use to move our eyebrows around but somehow doing that
with something like the hair on top of our head and making an unusual shape out of it.
I mean, you know, it doesn't make any sense to us.
Maybe to a bird it makes more sense, but that's pretty amazing.
Shape shifting's not really a technical term.
Is this strategy of turning into a black oval common in birds or found in any of the other
birds?
Certainly there are some other birds that utilize their body parts to modify their shape.
The common one I think that people, at least in North America, are familiar with would
be a turkey.
So a male turkey when he's strutting himself, he fluffs out his feathers and he fans his
tail.
And, you know, basically if you're a bird with feathers and you stick them all out in
some ways you're going to create something that's blob or oval like, so it's not too
much of a stretch to think that, you know, this can happen.
But no bird that I know of do it quite the way that birds-of-paradise do, where the transition
is so extreme and so precise.
And it’s not just the spread tail but it’s a combination of feathers from the tail, the
sides, back of the neck that all line up to make a form that looks so un-birdlike when
it’s done, and it’s so specialized and has been incorporated in a very precise way.
That level of modification, or that level of shape shifting, I don’t think – hasn’t
any precedence in any other birds.
So that black oval, did it just evolve once in birds-of-paradise and that they sort of
got it and everybody has a variation on the theme?
It’s possible although it’s not really clear that the, that the desire to have a
black oval like shape as the thing that’s the object of affection might have evolved
once, meaning that the females have this preference for things that look bigger than the body
of the bird, that are black and are highlighted with colors.
But what’s definitely not the same is that the way different species of birds-of-paradise
males have evolved to present that oval shape.
So some do it with their wings, some do it with feathers of their sides, of their breast
and their flanks that they lift up around their head.
Others do it with a different set of feathers from the breast and flanks they wrap around
their body in another orientation.
The superb bird-of-paradise creates its oval shape by using modified feathers on the back
of its neck that it lifts around its head.
So even thought they superficially look similar at the level of being black ovoids, they’re
fundamentally different in the way that they’ve evolved over time through sexual selection
to be an oval.
One of the things about an oval is that it matters how you look at it.
Once they’ve transformed it’s all about perspective, right?
Yeah.
The transformation into this ovoid shape typically happens when the female is in view of the
male and she’s showing these signs of either coming and flying and landing right where
he’s going to be or he has some expectation that she’s going to arrive.
He’s definitely always presenting and facing her so that she sees the part of the ovoid
presentation that has the highlights and the colored feathers or has their proper shape.
And if the female moves the male just has to move with her so that she can always see
the part that she’s suppose to see.
Because if you look at any one of these shape shifting birds of paradise from the wrong
side it’s not as impressive as it is from the side that the females have selected.
You ask anybody, you can ask a second grader or anybody, an adult to draw a picture of
a bird and you’re basically going to get one of two things.
You’re going to get a line with some wings coming out and pretty much all birds when
they’re flying they have that wing-bird shape.
And then maybe this kind of like sitting perch bird shape.
But you certainly wouldn’t in your wildest imagination, draw a bird that looks like it’s
wearing a ballerina’s tutu or some kind of psychedelic smiley face, right?
I mean, this is outrageous and without precedence and, you know, that’s just cool.
How could you not want to know how on earth birds came to use these kinds of shape for
courtship display?