Penguins are not mammals, even though they are warm-blooded animals. Penguins are one of only a few species of flightless birds left in the world. Many people mistakenly believe penguins have fur instead of feathers because of the extremely tight packing of the feathers on their bodies.
Birds lay eggs and are not mammals. When penguins mate, the male watches the eggs while the female gathers the food. With the notable exception of the Galapagos Islands, penguins live in cold areas in the Southern Hemisphere. Most birds could not survive the frigid temperatures, but penguins store ample fat reserves that protect them in the water. They also have the tightly-woven feathers that protect them on land, and they stand in huddles to block cold winds and share body warmth.