Saturday, June 11, 2011

Snap, Crackle, Pop

     I hated Rice Krispies as a kid.  You had to wet them with milk for them to do their snapping act, and they got soggy so fast that the audio fun was eclipsed by culinary mush.  Not so with Manakins.  They can snap all day long.
     As is obvious from the two previous entries, development of this blog was inspired by a trip to Panama.  (There will be plenty of North American stuff later). One of the target groups on this trip was the Manakins (Pipridae).  Manakins are sparrow-sized birds, not related to the Nutmeg Mannikin, which seems to be popping up all over the US and elsewhere.  Male manakins are brightly colored, and they "dance" in leks.
You've probably seen video of one or another species doing the Michael Jackson "moonwalk".  I was fortunate to have Carlos Bethancourt of Canopy Tower lead me to where Golden-collared Manakins were displaying.
     The males are pretty, yellow and black, with yellow neck feathers that stick out parallel to the beak when they are in display mode.  But the amazing thing about these birds is the sounds they make.  Golden-collars are pretty basic, with whirrs and snaps, but the snap is so loud that some people jump or gasp when they hear it for the first time.  I sure did.
     Unfortunately my humble video can't show how this snap is produced, but you can tell it is wing-driven. Here is a brief clip of a snapping manakin. These are called "roll snaps". You hear two sets of two rattles.  Each rattle is made up of 8-10 individual snaps.  Individual snaps are 20 milliseconds apart.


video
                                       For higher definition: http://vimeo.com/25436362

In 2003 Kimberly Bostwick and Richard Prum of Cornell University published high speed video of a White-collared Manakin doing it.  http://jeb.biologists.org/content/206/20/3693/suppl/DC1 You can see that the wings are beating against each other at about 50 beats per second.  I was confused when my video (slowed down) showed a snap sound coming from the bird at a time when the wings were obviously not touching.  Turns out that it happens so fast, that the wings were indeed already apart before the sound travelled the 7 meters or so to my microphone.  It's still hard to understand how feathers hitting each other can make such a loud snap.  Even Bostwick and Prum weren't exactly sure if there was something else involved. http://jeb.biologists.org/content/206/20/3693.full.pdf+html.  If these birds' parents aren't around, maybe they're cracking their knuckles. Do old manakins develop arthritis?

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