Migrating ospreys have problems - they have to catch fish every day to keep going. They are superbly equipped for the job. They have eyesight so sharp that they can see a fish underwater from 30 metres up. Split second calculation of the target speed, depth, size - and they dive. Talons open. Hip joints swing the weapons forward into strike position. Young ospreys have not been taught to fish - they learn through practice. Learning fast is a matter of life and death.