They are a group of viruses that cause diseases in mammals and birds.

它们是一组引起哺乳动物和鸟类疾病的病毒。

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And as most mammals and birds experience REM sleep, it's presumed that they do, too.

同时大部分的哺乳动物和鸟类都做过REM类型的梦，我们姑且推测它们都会做梦。

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It can infect mammals and birds, but scientists know little about its effects on its victims.

它可以感染哺乳动物和禽类，但是科学家们对其影响受害者知之甚少。

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He says they are part of the genome of the last common ancestor of all birds,frogs, dinosaurs and mammals.

VOA: special.2010.06.29

From a psychological point then, animals have evolved to be nice to their kin, particularly their children, and particularly in birds and mammals.

从心理学角度看，动物进化趋向于对自己的亲人有益，特别是自己的孩子，以鸟类和哺乳类为代表。

耶鲁公开课 - 心理学导论课程节选

Birds and mammals invest in quality and not quantity, as opposed to fish and reptiles.

鸟类和哺乳类靠质生存,而非以量取胜，这与鱼类和两栖类不同。

耶鲁公开课 - 心理学导论课程节选

According to the Northwest Marine Conservation Initiative, the nets are responsible for killing tens of thousands of marine life, mammals and birds every year.

CNN: Stimulus money pays fishermen to snare lost nets

Plants also provide habitats and food for mammals, birds and invertebrates around the globe.

CNN: STORY HIGHLIGHTS

And, while copia and its close relatives are not normally found in anything with more backbone than a reptile, its activities may hold clues about the behaviour of some of the other, more complicated, transposable elements that are found in those more complicated vertebrates, the mammals and the birds.

ECONOMIST: Truly selfish genes