1.Syrinx is sound producing organ of the birds .This is
unique to birds. It is made up of expanded tympanum.
2.Birds
have a single left ovary. This is an adaptation to reduce the unnecessary weight, which is not required during flight.
3.Bones of birds are
unique. They are strong but weigh very little because of air cavities (pneumatic bones). There are 9 air sacs in pigeon.
4.Leveret is the young one of hare(a mammal).
5.The base of wing quills are covered by the small
feathers which are similar to the quill feathers .These are known as underwing coverts
6.Apteeryx is the zoological name for kiwi. It belongs to the order apterigiformes