Once a clever magpie was building a nest for herself. All the other birds gathered around her to watch her build it and learn how to make one. However, none of them had the patience to watch till the end, and they rushed away to build their own.
The magpie had nearly finished making her nest and needed to add only one more twig, when a turtle dove asked her to add two instead of one. The dove kept bothering her till the magpie got angry and flew away to another tree. The other birds returned to learn the rest of the craft, but unable to find the magpie each bird had to make their own nest.
Their knowledge remained incomplete and this is why different birds have different nests.