While scientists have assessed the status of more than 147,000 plant & animals, there are thousands of species considered too "data deficient" for a full assessment. As a result, those species haven't been included in the listing of threatened or endangered species, updated each year by IUCN.
Monarch Butterflies Are Placed on IUCN Red List
All the world’s freshwater dolphins are now under threat of extinction, following news that an Amazon species has been added to the IUCN's endangered list