20163
All four extant populations were classified as endangered by the IUCN in 1996 , since less than 2,500 mature individuals were living in the wild and the population numbers continue to decline .
 IUCN
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 IUCN