Question

why does the mother bird sit on the eggs​

Answer 1

Birds have to sit on their eggs to keep them warm. It's a bit like baking a cake - the warmth from the parent bird makes sure that the chicks inside develop properly. This is called 'incubation'.

To keep the eggs warm, a special warm patch grows on the parent birds' tummies. Some of their feathers drop out so that the warm skin touches the eggs. This is called a 'brood patch

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