<p class="ql-block">鸟，又称作鸟儿。定义：体表被覆羽毛的卵生脊椎动物，鸟的主要特征是：身体呈流线型（纺锤型或梭形），大多数飞翔生活。体表被覆羽毛，一般前肢变成翼（有的种类翼退化）；胸肌发达；直肠短，食量大消化快，即消化系统发达，有助于减轻体重，利于飞行；心脏有两心房和两心室，心搏次数快。体温恒定。呼吸器官除具肺外，还具有多个气囊辅助呼吸，使得鸟类无论在吸气和呼气时，均有氧气通过肺，即双重呼吸。</p> <p style="font-family: -webkit-standard; white-space: normal; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.301961); -webkit-text-size-adjust: auto;">美洲秃鹰</h3> <p style="font-family: -webkit-standard; white-space: normal; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.301961); -webkit-text-size-adjust: auto;">林鹳</h3> <h3>大鹦鹉</h3> <p style="font-family: -webkit-standard; white-space: normal; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.301961); -webkit-text-size-adjust: auto;">黄鹦鹉</h3> <h3>黑天鹅</h3> <h3>白鹭</h3> <p style="font-family: -webkit-standard; white-space: normal; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.301961); -webkit-text-size-adjust: auto;">红翅黑鸟</h3> <p style="font-family: -webkit-standard; white-space: normal; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.301961); -webkit-text-size-adjust: auto;">澳洲银鸥</h3> <h3>白天鹅</h3> <h3>北美红雀（雄）</h3> <p style="font-family: -webkit-standard; white-space: normal; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.301961); -webkit-text-size-adjust: auto;">北美红雀（雌）</h3> <h3>大蓝鹭</h3> <h3>红嘴巨鸥</h3> <h3>海鸥</h3> <h3>褐鹈鹕</h3> <h3>红脚鲣鸟</h3> <h3>纳斯卡鲣鸟</h3> <h3>军舰鸟</h3> <h3>红嘴热带鸟</h3> <h3>漫游鹬</h3> <h3>熔岩鹭</h3> <p style="font-family: -webkit-standard; white-space: normal; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.301961); -webkit-text-size-adjust: auto;">燕尾鸥</h3> <h3>美洲蛎鹬</h3> <h3>黑颈长脚鹬</h3> <h3>蓝脚鲣鸟</h3> <h3>不会飞的鸬鹚</h3> <h3>小海燕</h3> <h3>条纹鹭</h3> <h3>杓鹞</h3> <h3>加拉帕戈斯鹈鹕</h3> <h3>朱砂鹟</h3> <h3>牛背鹭</h3> <h3>达尔文雀（1）</h3> <h3>达尔文雀（2）</h3> <p style="font-family: -webkit-standard; white-space: normal; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.301961); -webkit-text-size-adjust: auto;">玫瑰琵嘴鹭</h3> <p style="font-family: -webkit-standard; white-space: normal; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.301961); -webkit-text-size-adjust: auto;">鸬鹚</h3> <h3>鹦鹉</h3> <h3>鹩哥</h3> <p style="font-family: -webkit-standard; white-space: normal; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.301961); -webkit-text-size-adjust: auto;">鸊䴘</h3> <h3>棕头鹭</h3> <h3>加拿大大雁</h3> <h3>红头啄木鸟</h3> <p style="font-family: -webkit-standard; white-space: normal; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.301961); -webkit-text-size-adjust: auto;">白胸五子雀</h3> <h3>黑眼草鸟</h3> <h3>白喉麻雀</h3> <p style="font-family: -webkit-standard; white-space: normal; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.301961); -webkit-text-size-adjust: auto;">冠形捕蝇鸟</h3> <h3>阿尔巴鸟</h3> <h3>大乌鸦</h3> <h3>雅各宾鸽</h3> <h3>浪漫鸽</h3> <h3>黑头海鸥</h3> <h3>北美歌雀</h3> <h3>高地矶鹞</h3> <h3>角猫头鹰</h3> <h3>蜂鸟（1）</h3> <h3>蜂鸟（2）</h3> <h3>帆背潜鸭</h3> <h3>棕硬尾鸭</h3> <h3>水牛鸭</h3> <h3>黑颈天鹅</h3> <h3>北美鸳鸯</h3> <h3>鸽子</h3> <h3>黑冠山雀</h3> <h3>北方闪鸟</h3> <h3>金翅雀</h3> <h3>美洲鸫</h3> <h3>玫瑰胸松雀</h3> <h3>灰猫鹊</h3> <h3>北美鸭</h3> <p style="font-family: -webkit-standard; white-space: normal; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.301961); -webkit-text-size-adjust: auto;">雪鸮</h3> <p class="ql-block">沙丘鹤</p> <h3>小蓝鹭</h3> <h3>绿鹭</h3> <h3>美洲蛇鸟（雄）</h3> <h3>美洲蛇鸟（雌）</h3> <h3>红肩鹰</h3> <h3>欧洲雏鸟</h3> <h3>火鸡头秃鹫</h3> <h3>鹗</h3> <p style="font-family: -webkit-standard; white-space: normal; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.301961); -webkit-text-size-adjust: auto;">麝香鸭</h3> <h3>白朱鹭</h3> <h3>翠鸟</h3> <h3>白鹭鸶</h3> <h3>海鸠</h3> <h3>角嘴海雀</h3> <h3>北极鼻管鸥</h3> <h3>巴尔第摩黄鹂</h3> <h3>秋沙鸭</h3> <h3>金眼鸭</h3> <h3>火鸡</h3> <h3>鹰</h3> <h3>蓝松鸦</h3> <h3>亚洲鸳鸯</h3> <h3>乌鸦</h3> <p style="font-family: -webkit-standard; white-space: normal; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.301961); -webkit-text-size-adjust: auto;">白鹈鹕</h3> <p class="ql-block">谢谢你的观赏！</p>