how much does a whooping crane eat per day?
To figure out exactly how much they eat you would have to know the exact weight of the bird, the calories in the food, and the condition of the bird. Which is a very long way of saying that I don't know the answer to your question, but there is a mathematical way to figure it out if you are really interested.
The metabolic cost of flight depends on the type of flight (gliding, soaring, flapping, or hovering), wing shape, and speed. Of course, flapping flight and hovering are the most costly types of flight. Laboratory studies of birds trained to fly in wind tunnels (like the one below)
