One way they do that is by having evolved special energy conservation mechanisms. For example, at night, they can lower their body temperature as much as 25 degrees to nearly match the ambient temperature. Since Newton's Law of Cooling ensures that heat flows from warmer to cooler regions, and at a rate determined by the degree of the difference, they give up almost no heat at night to the surrounding air.
Different species have evolved equally astounding abilities.
- Some live as high as 12,000 feet where the air is too thin to support fast flight. They hop-fly along the ground instead, feeding off flowers close to the Earth.
- One species build their nests near Cooper's Hawk nests because the Coopers prey on the hummingbird's predators, but leave the hummers alone. That's particularly odd, since the hawk loves to eat small birds and their eggs.
- Those nests are built of leaves, lichen, and — get this — spiderwebs to hold it all together.
- Most of the species in the U.S. and Canada migrate from Central America, flying 3,0000 miles north — including 500 miles over the open water of the Gulf of Mexico (an 18 hour flight) without rest.