Eg tigers should have a relatively spacious place they can mate, but narrow piece of land of the zoo did affect their proliferation.

Lots of birds during proliferate, males need to charm the female by the beautiful feathers often "dance performances," but after we left the zoo in "formless voiceless".

Birds have adapted in a quiet place, but in noisy places such as zoos do not get it. There are many animals at the zoo are included in sexual maturity is not good, nor to death is birth.

That's why the world today, the protection of nature and environment have tried a lot in the construction environment in the zoo wild race to conserve the endangered animals.