Flying is something that we dream about, that
is without standing in line to get on an aircraft, but we’re not built for imitating
the birds. The closest we’ve got so far is imitating flying squirrels as
demonstrated this week by Gary Connery who hopped out of a helicopter at 2,400
feet (1).
Both
birds and bats have been flying about the sky for a very long time and are very
proficient. Until now I had just admired their expertise, but Muijres et al haven’t been satisfied with simple
admiration (2). They have been checking out their relative aerodynamic
efficiencies and have tossed three pied flycatchers, a blackcap, two Pallas’
long-tongued bats and finally two lesser long-nosed bats into a wind tunnel to
check the disruption in airflow behind the victims.
The
combination of photography and airflow velocity measurements enabled the team
to estimate their relative flight efficiencies from such factors as
lift-to-drag ratios and mechanical cost-of-transport.
The
conclusion for birds versus bats? Well, both species have evolved optimum wings
and flight efficiencies for their preferred flight patterns, but on balance
they conclude that birds have the edge as flying machines. Hence birds migrate
over longer distances and fly faster.
Could
be that they have had rather longer in the evolutionary game and maybe bats are
generally more laid back, preferring to sleep the winter away rather than
having to fly halfway around the world following the sun.
- http://news.discovery.com/adventure/connery-plunge-120523.html
- http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0037335
