All birds have most of their body covered with feathers.
And these feathers are important for flight, and for maintaining body temperature, and
they’re used for protection from the elements; it’s like putting on a coat or a rain jacket.
All birds also use feathers for some element of coloration that might be - to be more cryptic
and camouflaged or to be more conspicuous and colorful.
And in birds-of-paradise, feathers are playing all those same roles but then you have this
whole other realm where not only are they colorful, not only are they being used for
courtship display but they’re actually modified into something so unfeather-like in many cases
that they’re without precedence in all of the rest of bird world.
And that’s really incredible to me that all of these feathers that are so unusual
all have their origins back to that same basic feather that we’re familiar with from all
those other birds.
Birds-of-paradise, a lot of their feathers
have been modified to show off color and shape to the extent that those feathers are hardly
useful.
They don’t help with insulation at all, the feathers have a completely different structure.
If you only had those kinds of feathers the bird would probably not survive well if it
was cold and wet.
A tail that’s three feet long doesn’t help with flight; it’s like, you know, an
airplane pulling along a huge streamer.
It looks cool, it might tell us something like, you know, come to the beach or whatever
it might say, but it doesn’t help the plane fly better.
Some birds-of-paradise have feathers that have shapes that when you’re looking at one
individual feather it doesn’t really make sense.
But then they put them together with a bunch of other feathers of unusual shapes and create
these meta-structures.
We think of it as the shape shifters usually the ones that transform themselves into something
very un-birdlike.
And those creations are created with feathers of some sort.
Sometimes they’re feathers of the body, sometimes they’re the wings.
What are the most unusual feathers in the group?
The most unusual feathers in the birds-of-paradise, and they’re some of the most unusual feathers
in all of birds, are the ones where what we think of the typical feather structure has
been lost.
And what’s happened is that the feather which has a central shaft and all these little
smaller branches that come off of it that make the vein of the feather have been fused
together so it actually looks like a plastic tab or a piece of plastic.
And that’s what we see on the king-of saxony which has feathers which come off from behind
the eye which typically should be, you know, very small, and these have been elongated
through the process of sexual selection to being twice as long as the body of the bird
and fused so you have this incredible non-featherlike plastic structure.
But that’s not the only instance where you see that fused plastic like structure.
We actually also see it in the tail-wires or tail-ribbons, because they’re more ribbon
like, in the red bird-of-paradise which doesn’t have the typical wire that we see in some
of the other Paradisaeidaes, but it actually has this long fused plastic curlicue.
They’re very rigid and they hold their shape in a really unusual way, but it’s the same
kind of processes that’s gone on with the fusion of the feathers in the king-of-saxony.
How does a bird control, if it’s just connected to its skin, where that feather goes and how
they move them around their bodies?
All birds have a set of very small muscles that are in the skin of the bird that attach
to the base of every feather and can be pushed and pulled on different ways so that the feathers
move.
And if you think about a bird that’s fluffing itself up or preening, the bird can move its
feathers out away from the body and back down.
So essentially what birds-of-paradise are doing with these really long and very unusual
highly modified feathers, is they’re doing the same thing, they’re using the same sets
of muscles in the skin and they’re able to move them.
But what’s extraordinary is that they have had some evolution going on under the surface
that we can’t see that’s made those muscles much stronger and more robust to give them
more degrees of movement than we typically think and also with an incredible amount of
precision.
A bird like that with those incredible precision, long feathers, they don’t have to grow those
every year, do they?
All the feathers on the bird are re-grown every year so it doesn’t matter whether
they’re just the tiny normal contour feathers or they’re the three-foot long tail feathers
on the ribbon-tailed astrapia.
Somehow all those feathers are regrown every year, as improbable as it seems even when
you see a bird that’s re-growing them.
It’s hard to believe that it can regenerate something so unusual over the course of the
year, and usually it’s only over the course of several months.
So when we think of birds, I think we often think of two things: feathers and flight.
But something the birds of paradise have in their feathers that’s not as common among
most birds is how extremely modified these feathers have become to be used as vehicles
of carrying color or ornaments that can help change their shape and appearance.
So it’s this kind of gross modification of the feathers for no other purpose than for courtship
that really makes the birds-of-paradise stand out among the whole bird world for types of
feathers and how they’re used.