The Fascinating Hummingbird

The hummingbird has fascinated both naturalists and engineers.  A video of the Black-chinned Hummingbird  (also shown in the picture) that visits our backyard feeder is now available on Youtube at http://youtu.be/ljXb8siXI-Q

In the video, if you carefully observe you will notice the tongue of the bird sticks out after it has withdrawn its beak from the feeder.  This observation prompted me to investigate the role of the tongue in feeding.  Surprisingly, it was not until 2011 that the mechanics of hummingbird feeding was elucidated and some misconceptions removed. It was thought that the hummingbird drew the nectar by capillary action through a fine tube.  Today we know that the hummingbird has a forked tongue that allows the nectar to be aggregated on thin hair-like structures along the length of the tongue.  The nectar trapped on the hair-like structures is consumed when the tongue is withdrawn into the beak.  These structures are discussed in detail in a paper published in the Proceedings of the National Academy of Sciences (June 7 2011) downloadable for free at http://www.pnas.org/content/108/23/9321.full.pdf+html.   When designing micro-aircraft, we also learned that the hummingbird flying at 30 kmph ( a typical flight speed)  dissipated about 4 Watts of metabolic power.  A typical hummingbird weighs less than 3 to 4 grams.  The power-to-weight ratio is 1000 W/kg an enormous value comparable to that of a V8 diesel engine in a car.   Thus, the hummingbird’s heart beats at the rate of 500-1000 times a minute and the bird needs to feed every fifteen minutes to keep up with its metabolic requirements. As a result, hummingbirds are always at the brink of starvation. I am sure that this hungry creature will appreciate a feeder in your backyard. I recommend using just plain cane sugar solution ( 1 cup of sugar  plus 4 cups of water) with no fancy additives.