This is a male magnificent riflebird.
He’s got this incredibly clear, powerful whistle that just carries great distances
through the dense lowland forest where he lives.
And here’s a male black sicklebill.
He also makes an incredibly powerful sound from his courtship display territory.
In both cases the males are using these calls to advertise to females a great distance that
this is their courtship display area.
But they’re also announcing their presence to other males who have territories nearby.
And clearly, as you can see, both of these sounds are vocal, meaning that they are created
with the same vocal apparatus that all birds use to produce sound – their bill, their
trachea, their syrinx.
Another thing these two species have in common is that they both produce nonvocal sounds,
that is they make sounds with parts of their body that we don’t typically associate with
sound production.
Let’s check out how they do it.
This is the male black sicklebill again.
His nonvocal sound is a knocking, it sounds like a distant machine gun.
From this view you can tell he’s not making that sound with his mouth.
His bill is closed.
But it’s a little bit hard to tell where it’s coming from and what’s going on.
Fortunately on this day we had two cameras recording at the same time.
What you can see from this other camera is that as he does this display and he comes
upright, he actually opens his wings across his back.
It’s a little hard to see what’s going on there, but those are his wings and those
primary feathers are spread across the back and as he lunges forward he closes those wings
across his back and somewhere there either between the feathers rubbing against themselves
or perhaps against the base of the tail, that’s where he’s creating that nonvocal sound.
So now we’re looking at the male magnificent riflebird.
He makes his nonvocal sound in courtship display somewhat like the black sicklebill, but he
does it in a very different way.
As you can see, he’s opening his wings up and he’s moving his head from side to side.
And when he’s doing that he’s moving his wings.
That sound that you hear is being produced by the opening and closing of the wings.
It sounds like a pronounced rustling.
Another really cool aspect of this nonvocal sound is how directional it seems to be.
Notice when he turns around the sound gets louder.
And that’s because he’s directing that sound towards the female, and in this case
it also happens to be directed towards our microphone, so it’s picking up the sound
as well.
Although there’s never been any good research on this, it’s possible that the shape of
his wings would have something to do with projecting that sound in the direction of
where the female is; almost like it’s an amplifier or like a megaphone.
What’s cool is, is when we think back to the black sicklebill, he also seems to have
this curved kind of megaphone aspect to his courtship display.
And we know that the female, just like on the magnificent riflebird, she also sits right
in front of the male when he makes his knocking sound.
So it’s possible that both of these species have this directional element, directing that
nonvocal sound right where they want it to be, where the female is when she’s watching
their courtship displays.
Clearly both these species have extraordinary vocal sounds.
But it’s these nonvocal sounds that they make in their displays that really sets them
apart from other birds-of-paradise.