From underneath, the white belly is difficult to detect against the shimmering sun filtering down from the ocean's surface. Wings have become flippers that are stiff, strong and narrow. Unlike other birds, which have hollow bones, the penguins' bones have become solid and fused for rigidity. Feathers are very small with approximately 70 per square inch. They are coated with oil for waterproofing.
Special glands remove salt from water and food.
It is dissolved in water and flows down grooves in the beak to drip off the end. Bare skin, forming pink patches around the eyes, aids in heat dispersal when the birds leave the cold water to rest on the relatively hot shore. Humboldt penguins are SSP animals. Over-hunting of bat guano has greatly reduced available breeding areas. Roger Williams Park Zoo is a participant in the Species Survival Program, a cooperative effort by zoos to manage the population of rare and endangered animals.