The main component of feathers is keratin, a flexible protein that also forms the hair and fingernails of mammals. Feathers provide the strong yet lightweight surface area needed for powered, aerodynamic flight. They also serve as insulation, trapping pockets of air to help birds conserve their body heat. The varied patterns, colors, textures, and shapes of feathers help birds to signal their age, sex, social status, and species identity to one another. Some birds have plumage that blends in with their surroundings to provide camouflage, helping these birds escape notice by their predators. Birds use their beaks to preen their feathers, often making use of oil from a gland at the base of their tails. Preening removes dirt and parasites and keeps feathers waterproof and supple. Because feathers are nonliving structures that cannot repair themselves when worn or broken, they must be renewed periodically. Most adult birds molt — lose and replace their feathers — at least once a year.
- keratin [ˈkerətin] n.角质
- flexible [ˈfleksəbl] adj. 柔韧的
- mammal [ˈmæməl] n.哺乳动物
- aerodynamic [ˌɛərəudaiˈnæmik] adj.空气动力学的
- insulation [ˌɪnsjuˈleiʃən] n.绝缘，绝热
- trap [træp] v.捕捉
- conserve [kənˈsə:v] v.保存
- texture [ˈtekstʃə] n.质地
- social status [ˈsəuʃəl - ˈsteitəs] n. 社会地位
- blend in [blend - in] v. 与(环境等)协调
- camouflage [ˈkæmuflɑ:ʒ] n.伪装
- predator [ˈpredətə] n.捕食者
- beak [bi:k] n.喙
- preen [pri:n] v.(鸟)用嘴整理(羽毛)
- gland [ɡlænd] n.腺
- tail [teil] n.尾
- parasite [ˈpærəsait] n.寄生物
- waterproof [ˈwɔ:təpru:f] adj. 防水的
- supple [ˈsʌpl] adj.柔软的
- worn [wɔ:n] adj.用旧了的，磨破了的
- periodically [ˌpiəriˈɔdikəli] adv.周期性地
- molt [məult] v. 换毛
