'Flap-running' in birds studied

MISSOULA, Mont., June 27 (UPI) -- "Flap-running", where birds furiously flap their wings while running on the ground, may have been a key step in the evolution of flight, U.S. researchers say.

Experiments with pigeons by researchers at the University of Montana have shown the technique helps birds ascend slopes and suggests the earliest flightless birds might have used the same technique, the BBC reported Monday.

Researcher Brandon Jackson and colleagues said they wanted to find out why birds completely capable of flight would continue to use the "flap-running" technique.

They suspected birds might be using the technique to save energy, they said.

The researchers implanted electrodes in the flight muscles of pigeons, birds that often flap and run despite being excellent fliers.

Measuring energy use as the birds used "flap-running" to ascend a 65-degree incline, they found that running and flapping up the ramp "required about 10 percent as much power from the flight muscles," Jackson said.

"The birds seemed to be using hardly any power to flap their wings as they ran up the slopes."

The technique is also an essential developmental step for fledgling chicks, the researchers said.

"Flap running ... lets young birds that cannot yet fly -- because of small muscles, small wings, weak feathers, etc. -- get off the ground and away from some predators," Jackson said.

"And if baby birds can perform these behaviors, benefit from them, and transition gradually to flight in their life-time, we think it's probable that dinosaurs with [similarly small wings] could have performed these behaviors, benefited from them, and transitioned towards flight over evolutionary time."