bird的复数形式怎么写

　　例句：

　　1、This species of bird is decreasing in numbers every year.

　　这种鸟的数量在逐年减少。

　　2、 The area has a wealth of bird life.

　　这个地区栖息着大量的鸟。

　　3、The lake is noted as a home to many birds.

　　这个湖作为许多鸟类的栖息地而闻名。

　　4、Huge numbers of birds had flocked together by the lake.

　　成群的鸟聚集在湖边。

　　5、 The male and female birds take turns in sitting on the eggs.

　　雄鸟和雌鸟轮流伏窝。