Would a lorry carrying a flock of birds change weight if the birds were flying? This is a riddle that has perplexed scientists until now.
Thanks to a newly developed device, researchers have demonstrated that the weight of a container fluctuates as the birds inside flap their wings. The tiny device measures the force as a bird's wings flap. Results showed that whilst hovering, birds create double the lift during the downstroke of the wings so that during an upstroke they don't need to lift their weight.