Flying birds lost

birds that can not fly,they are said to be flying vigorous birds.
They are primarily dependent on swimming and running for self defense.
There are about 40 species of birds in the world which can not fly. Excessive flying birds have been extinct from the earth.
Most of the nomadic birds are mostly islanders. It is believed that there is no need to fly to protect the ancestors of these birds because there is no predator on the island.

That is, due to the gradual disappearance of their flying power. Large angled birds, such as the ancestors of ostrich, riya, emu, casewari etc., did not need to be strong legs, strong claws, and the ability to swiftly run for self-defense in order to run faster.
Among the living birds of the world, the largest number of inaccessible island membranes (length 12.5 cm and weighing 34.7 grams) are the smallest and ostrich (length 2.7 m and weighing 156 kg).
In fact, ostrich is the world's largest bird.
However, some birds used to run on earth once in a while, which were significantly larger than ostrich in size.

Birds that can not fly, their chests or strains and wings of the wings are much shorter than flying birds. In any species, there is no strain.
The key is to keep the muscles necessary for flying. Some of these species do not need the key. Besides, the feather of these birds is much higher than the birds capable of flying.

The feathers of these birds are spread evenly on the skin. But feathers in the Flying Birds extend into a region-based or sparse area.

Flying birds are noticed in the vulnerability of birds. Poor cocktails and ducks have reduced flying ability. But their ancestors, respectively, have the ability to fly between the Red Forest and Nilshi duck respectively