OT I sent your post to a friend who runs marathons. He gave me an interesting reply when I asked about calorie use.
"That's fascinating to read of something new in the world of science that didn't have to come from the depths of the universe to be amazing.
Let's see about the calories. 50% of a 1.5 pound bird is fat at departure. So that's 0.75 pounds which is burned off completely. Now assuming that that's their only source of fuel for the flight, at 3,500 calories per pound of fat, they'd each be burning 2,625 calories.
Interesting number. A 160 pound man burns 100 calories per mile whether walking or running (the latter balances the higher burn rate by getting the mile over with sooner). A marathon is 26.2 miles, so this person would burn, over the course of a marathon, the same number of calories as the godtwit over the 7,000 mile migration.
Now the man weighs about 107 times as much as the bird. So the man running the marathon is like the bird running 2,795 miles. So it appears that while flying the 7,000 miles, the godtwit is about 2.5 times as efficient as a human running."
Norman
