It is a bird, but it has features more characteristic of a mammal. It has tiny wings, but cannot fly. It has loose feathers that are more like fur and unlike other birds the feathers moult throughout the year. It is the only bird in the world with nostrils at the end of its beak. Its sense of smell is second to none. It has no tail feathers, but does have whiskers, like a cat.It has marrow in its bones, just like a human. The kiwi have one of the largest egg-to-body weight ratios of any bird. The egg averages 15% of the female's body weight (compared to 2% for the ostrich).