German researchers say a couple of barn owls named Happy and Tesla, tracked by a moving camera system, are helping them learn about the secrets of bird flight.

The scientists have collected data from Happy, the older of the two, recording how an owl moves during gliding flight. They are now conducting studies with both Happy and Tesla of what happens as the birds beat their wings, said Thomas Wolf, a researcher at the German Aerospace Center's Institute of Aerodynamics and Flow Technology.

Owls were chosen as study subjects because they begin flying slowly, making tracking them with the moving camera system easier, LiveScience.com reported Tuesday.

However, figuring out how a bird's wing changes shape during flight and during different flight patterns can be difficult, Wolf said, since the bird's path can't be predicted, even in a closed area as the bird flies toward food as a motivation.

"In some of the tests, the owl may fly slightly higher, or slightly lower; it all depends," Wolf Said. "Although this may cause difficulties, the owls should not be influenced in any way, since we want to ensure that the flight is as authentic as possible."

Eight video cameras record the owls' flight from above and below using a frame that moves along with the birds as the fly.

In addition to providing date about bird flight, Wolf and his colleagues said, the research may be applicable to small, unmanned aerial vehicles.