Saturday, June 11, 2011

Seeing birds in a new way

     Did you know that hummingbirds drink with the backs of their heads?  I didn't either until I shot this video.  It's a fine example of the sorts of subtle behaviors, plumages, and details of a bird's life that only video (or motion pictures) can capture.  I have been doing this for a lot of years, and decided it's finally time to put some of this stuff out where others can see it.

     As a first entry to this blog, here is a hummingbird.  This is a White-necked Jacobin, a bird common in Central and South America.  It was filmed at the Rainforest Discovery Center in Soberania National Park, Panama.  You may wonder, as do I, what is a Jacobin?  The term refers to a political group, active during the French Revolution.  Since this bird was first described in 1758, it is easy to see why a French Revolutionary name might have been ascribed to it, after it became known outside of scientific circles.  The best-known Jacobin, the infamous and deadly Robespierre, presided over the french Reign of Terror.  Since this rather large bird easily takes over whenever it appears at a feeder, one can see why it might have been named after that feared lopper of heads. There is also a breed of fancy pigeon called Jacobin.  Anyone know the real reason for these names?

     Anyway, watching this video, one is struck by the pulsation of the birds head as it feeds.  Is this some kind of suction device?  Turns out that it isn't.  Hummingbirds do not drink nectar like through a straw. They lap it up, like a dog or cat when there is plenty (at a feeder), or let it ride up the tongue by capillary action when ther isn't much (at a stingy flower). To feed, the tongue has to be extruded, and this is why the head pulsates.  A hummingbird's tongue is attached to muscles that run from the mouth, around the base of the skull, up the back of the head, over the top and finally end somewhere near the eyes.  These long muscles allows the tongue to stick out far enough to get at the nectar.  The pulsations you see are simple the flexing of the muscle.  Nectar is not sucked up into the rear of the head, like it may at first appear.

video
                                          For higher definition: http://vimeo.com/25437544

        This clip has been slowed down 8 times.  You can see that for each flex of the muscles at the back of the head, the bird actually swallows as the tongue is brought back in with its load of nectar.  The rate in real time is 7 per second.

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