The colony, discovered in a heavily forested area east of the Mekong River in Cambodia's Stung Treng Province, also represents one of the last chances for recovery of the species, now listed as "Critically Endangered" by the World Conservation Union.
"We discovered the nests on top of a hill where two other vulture species were also found, one of which -- the white-rumped vulture -- is also 'critically endangered,'" said Song Chansocheat, manager of the Cambodia Vulture Conservation Project. "Amazingly, there were also a host of other globally threatened species of birds and primates. It's a very special place."
Chansocheat and his team established 24-hour protection measures against poaching and egg collecting, and are now working to create longer-term conservation measures.
The slender-billed vulture is one of several species in Asia that have been driven to the brink of extinction across its entire range due to Diclofenac, an anti-inflammatory drug used for cattle that is highly toxic to vultures.