Endangered species, any species that is at risk of extinction because of a sudden rapid decrease in its population or a loss of its critical habitat. Roughly 99 percent of threatened species are at risk because of human activities alone. By the early 21st century it could be said that human beings (Homo sapiens) are the greatest threat to biodiversity. The principal threats to species in the wild are:
Habitat loss and degradation
Spread of introduced species
The growing influence of global warming and chemical pollution
Unsustainable hunting
Disease
'Endangered species' 2019, Encyclopaedia Britannica.