Monday, December 27, 2010

Gannets and boobies

When I saw photos of blue footed boobies in Dawkins' latest book (color page 24), my first thought was that these birds were excellent examples of signal selection.  Then I learned more about their natural history and behaviors and was even more impressed.  Birds make excellent photographic subjects.  Take a look at this gannet in the photo at left, a member of the Sulidae family with the blue footed booby, diving into the ocean, its wings are stretched out behind it, and its whole body is straight as an arrow before it plunges into the water.  It makes a very dramatic impression, falling like a meteor to the Earth, transforming to kinetic energy that which was only potential moments ago.  Many questions come to mind upon seeing this.  When it dives, why does it arrange its wings in this way, instead of say the way a falcon folds its wings when diving?  My guess is that a falcon must be ready to apply the air brakes quickly and slow down once it reaches its target, whereas a gannet's speed is slowed simply by the water friction after it enters the ocean, affording it the freedom to adopt this more streamlined position.  (I also wondered why there are no seabats, whereas there are numerous seabirds.  There are fishing bats, at least.  I think beaks and feathers are significant adaptations for an ocean going lifestyle allowing birds to out compete bats in this ecosystem.  But then, whence pterodactyls?)  Another interesting fact about gannets is that they have occluded nostrils.  The opening is inside their beaks instead of on the surface, so they breathe through the corners of their mouths.  This prevents water from going in their noses when they dive at speeds of up to 100 kph from 100 feet up.  I am convinced that there are some excellent videos of gannets and other members of the Sulidae family of diving seabirds online, but I haven't seen any yet due to my 40 kbps connection speed.  Will update if I find some.


  1. And Happy New Year to you too! I am cautiously optimistic about the potential of 2011 to bring welcome changes into our lives. (While simultaneously preserving the changes we already enjoy and have grown accustomed to.) Yep, that's evolution for you! :)