How to weigh a bird in flight

Scientists at Stanford University in the US have developed a device that can measure the weight of a bird in flight by measuring the force produced by every wing flap.

The invention, described in the Royal Society journal Interface, will enable researchers to carry out tests of miniature drones, to assess more precisely their flight performance.

To record such tiny forces from the birds' wings, the team trained two pacific parrotlets (named Gaga and Ray) to fly inside their specially designed chamber - shown in this clip with the force recordings shown underneath.

The footage is slowed down 100 times; the bird actually beats its wings 20 times every second.

The birds would receive a food reward "and we get its aerodynamic forces in return", explained team leader Prof David Lentink.

Footage courtesy of Lentink Lab