One in five of all known mammals and one in three amphibians are at risk of extinction, according to the latest update of the so-called "Red List" of endangered species.
The annual report, prepared by the International Union for Conservation of Nature, says nearly three quarters of plants and a quarter of reptiles assessed so far are also under threat.
The BBC reports that out of the 47,677 species in the IUCN Red List of Threatened Species, 17,291 were deemed to be at serious risk.
These included 21% of mammals, 30% of amphibians, 70% of plants and 35% of invertebrates.
Conservationists warned that not enough was being done to tackle the main threats, such as habitat loss.
