Zoos may be good or bad for animals, depending on the cleanliness of the facility, quality of the establishment, knowledge of zoo staff and other factors. Arguments supporting keeping animals in zoos argue zoos save animals from high risks of extinction. Arguments opposing housing animals in zoos cite the lack of replicating true environmental conditions, which jeopardizes the health and happiness of resident animals.
As technology and understanding of animals and their habitats emerge, zoos adapt a more natural setting for animals. Once confined to small cages of wood and metal, animals in zoos typically enjoy a larger living space often with water and accessories simulating those in their native environments, such as posts and small trees for birds and other tree-dwelling creatures.
Many zoos engage in special breeding programs, which zoo advocates believe enhance the survival rates for certain species. Zoos also provide research facilities, letting professionals study animals for improving their living conditions and likelihood of species survival in the future. They also incorporate educational and outreach campaigns into their programs, generating an understanding of the animals and awareness of their plights among members of the public. However, others argue raising animals in zoos reduces the likelihood of animals' chances of successful recovery in the wild. Animals become dependent on zoo handlers and trainers. Captive breeding produces high costs and only retains a small portion of the wild population's gene pool, resulting in inbreeding and health issues.