大象传媒

David Attenborough is with peacocks which are displaying on the lawn of a stately home. The peacock has some of the largest feathers in the world and some of the most spectacular, but they are a bit of a mystery.

Darwin himself, for instance, confessed that he was baffled by the sheer perfection of the feathers. Were they really developed just so the males could compete with other males and impress the females?

Crouched by a peahen's nest and eggs, David explains that egg production is a reptilian characteristic that birds have never lost.

Every other vertebrate group has some members that bear live young, but no birds do. The reason is that it would be a real handicap for a female bird to fly with the weight of a whole clutch of young inside her for as long as they take to hatch.

So birds lay the eggs in a nest as soon as they are formed. But that makes eggs vulnerable, so birds go to a lot of trouble to protect their eggs and nests.

A peahen, for example, makes a nest in a secluded place in the undergrowth and foregoes the attention-catching display feathers of her mate so that she is well camouflaged.

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