Birds Versus Bats

 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.


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