Habitat destruction, over hunting and exploitation of exotic plants and animals, climate change and inadequate funding for enforcement threaten many species near extinction according to a recent study published in Science Magazine. See the The IUCN Red List of Threatened Species for a breakdown.
International wildlife trade remains a leading threat to biodiversity conservation and is a common vector for infectious diseases and invasive species (4) that also affect agriculture, livestock, and public health. With 175 member countries, the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES) is the most important global initiative to monitor and regulate international trade of plants and animals. CITES regulates trade of nearly 34,000 species and has reduced threats associated with overharvest of imperiled species for international trade.
The United Nations claims the extinction rate for plants and animals is at the highest level since the dinosaurs died off 65 million years ago. Unregulated trade in endangered species is contributing factor.