Animals and birds should never be kept in cages.

Animal welfare has become a hot topic in recent years. Animal lovers have raised their voices many times to defend for the rights of their loved ones. The act of using animals as a commodity for human's purposes has been strongly criticized. Keeping them in cages is also included. While supporters believe that animals and birds should never be caged, I oppose that sometimes animals and birds should be caged for the following reasons.
Firstly, animals and birds bring considerable medical benefits such as bear gall and bird nest. According to scientists, bear bile contains ursodeoxycholic acid, which is believed to reduce fever, protect the liver, improve eyesight and break down gall stones. Meanwhile, edible bird nest is known to have anti-aging and immune-enhancing properties. Therefore, in such cases, they should be caged for experiments and researches, which then contribute to the medical development of mankind.
Secondly, captivity virtually brings them necessary safety at times as some kinds of birds will be protected from their predators once they are in cages. For instance, the baby birds can be easily killed by only one swift bite of the pet dogs, especially in spring and summer. To add on, red and gray squirrels are considered a great menace to the bird houses and the birds themselves. In the case of the chicken, some should be caged so that their eggs can be controlled for agricultural activities. Occasionally, when bird flu is widespread, chicken must be caged so that the disease can be managed so that no serious social impact will result.
On the other hand, the defenders argue that animals and birds should be given freedom. Cages will deprive them of their instinct features. They are unable to move about to search for the food and drink, create their own shelters and enjoy playing in their territories. All they do is sitting in the cages and eating the manufactured food their masters bring. For example, domesticated dogs become less aggressive and less