383. Other animals, it is true, communicate with one another by means of cries: for example, many birds utter warning calls at the approach of danger; monkeys utter different cries, such as expressions of anger, fear and pleasure.

译文

其他动物通过叫喊声相互沟通，这确有其事：例如，许多鸟在危险临近时发出警告的叫声；猴子发出不同的叫喊声来表示愤怒、恐惧和高兴。

点睛

it is true为插入语。
communicate with意为“与……沟通，交流情况”。如：
The police communicate with each other by radio. 警察通过无线电相互联络。
by means of意为“以……方式，通过……的手段”。如：
The theory is illustrated by means of Power Point. 该理论以PPT的形式进行讲解。
utter此处意为“发出（声音）”。如：
Why do you utter a sign? 你为什么要发出叹气声呢？
at the approach of意为“在……将到的时候”。如：
A bird has to give way at the approach of an elephant. 大象走过来，小鸟要让路。