What are reasons that lead to endangering of many species of plants and animals? How can we save those?

The last 20 years have seen the loss of 27 species. Some of the causes of this loss are: 
1. Habitat loss and fragmentation: This is the major cause of loss of biodiversity. Habitat destruction is caused by human activities such as deforestation and increasing pollution, leading to the loss of many plants and animals. Habitat fragmentation is the breaking up of the habitat of a particular species into fragments. 

2. Over-exploitation: Humans, because of their greed and increased exploitation of natural resources, have contributed to the endangerment of commercially important species of plants and animals. Species such as the Steller's sea cow and passenger pigeons have become extinct as a result of over-exploitation by humans. 

3. Co-extinction: When plants or animals become extinct, other plants or animals that are dependant on it in an obligatory way also become extinct. 

Endangered plant and animal species can be saved by adopting methods that do not disturb their environment. We need to protect the habitats in which they survive and also protect them from poachers and hunters. A lot of steps are being taken at personal and public levels to ensure their protection.