Читать книгу Skyward - Мэри Монро, Мэри Элис Монро, Mary Monroe Alice - Страница 17

Feathersare marvels of evolutionary adaptation. They are some of the strongest and lightest structures formed of living tissue and do more than merely help birds fly. When fluffed up, feathers form dead air spaces that act as insulators against the bitter cold. When pressed tightly against the body, they help to expel excessive heat. All birds periodically shed their old feathers and replace them with new. This is known as a molt.