I was watching a skein of geese flying south for the winter, individuals arranged in a typical V-shape, each bird pumping its wings up, down, up, down, hour after hour after hour. Just watching them, knowing how many hundreds, thousands, of miles they had to go before they reached their destination, made me exhausted.
Then there are the songbirds, who migrate so high that we don’t even notice them. How do they travel such long distances, exerting themselves where the air is so thin? Even more, they can fly and vocalize at the same time. (When I’m hiking at high elevations, it’s all I can do to gasp for air; I can’t even talk, much less sing!)