What percent of animals that live on land are endangered?

Approximately 25% of all terrestrial animal species are considered to be endangered or threatened with extinction, according to the International Union for Conservation of Nature (IUCN). This includes mammals, birds, amphibians, reptiles, and plants. The leading causes of endangerment include habitat loss, climate change, pollution, overexploitation, and the introduction of invasive species. Conservation efforts are underway to protect endangered species and their habitats, and to reduce the threats they face.