Habitat loss and hunting are among the primary threat factors for the animals on the list.
The 41-year-old female known as Nola saw her health take a quick turn for the worse.
The critter had held the dire designation since 1967.
These often solitary great apes with soulful eyes can look like philosopher-kings.
Scientists say they've figured out at least 13 different vocalizations used by the animals to express various emotions.
The eight-year-old male made a long journey to a specialist rhino sanctuary on Sumatra island from a zoo in Cincinnati.
As many as 25 of the critically endangered animal were observed in the Gulf of California.
A new analysis of population data causes alarm for conservationists looking across the next 20 years.
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