As the rich, biodiverse, tropical forests disappeared, so did habitat for indigenous animals. Uniform grassland has poor habitat diversity compared to the complex, multi-layered tropical forest. As a result, the number of bird and mammal species living in sprayed areas declined dramatically. Most of the forest animals are adapted to living in a specific habitat and are unable to survive in the post-herbicide grassland. Wild boar, wild goat, water buffalo, tiger, and various species of deer became less common once the cover and food resources of the forest were removed. Domestic animals such as water buffalo, zebu, pigs, chickens, and ducks were also reported to become ill after the spraying of Agent Orange.
The defoliation and destruction of the mangrove forests had other consequences to wildlife. The number of coastal birds declined dramatically, since their habitat had vanished. Fish and crustacean populations also suffered, since their former breeding and nursery habitats in the web of channels winding beneath the mangrove trees were destroyed. Additionally, the wartime spraying of mangrove forest is thought to have contributed to the post-war decline in South Vietnam's offshore fishery.