Photo released by the Wildlife Conservation Society (WCS) on Oct. 26, 2020 shows a Germain's silvered langur in Keo Seima Wildlife Sanctuary in eastern Cambodia. The Wildlife Conservation Society (WCS) released a report on Monday, showing a 10-year population trend for 13 key wildlife species found in the Keo Seima Wildlife Sanctuary (KSWS), Cambodia's most biodiverse protected area. (Allan Michaud/WCS/Handout via Xinhua)

Photo released by the Wildlife Conservation Society (WCS) on Oct. 26, 2020 shows green peafowls in Keo Seima Wildlife Sanctuary in eastern Cambodia. The Wildlife Conservation Society (WCS) released a report on Monday, showing a 10-year population trend for 13 key wildlife species found in the Keo Seima Wildlife Sanctuary (KSWS), Cambodia's most biodiverse protected area. (Ashish John/WCS/Handout via Xinhua)

Photo released by the Wildlife Conservation Society (WCS) on Oct. 26, 2020 shows wild pigs in Keo Seima Wildlife Sanctuary in eastern Cambodia. The Wildlife Conservation Society (WCS) released a report on Monday, showing a 10-year population trend for 13 key wildlife species found in the Keo Seima Wildlife Sanctuary (KSWS), Cambodia's most biodiverse protected area. (WCS/Handout via Xinhua)

Photo released by the Wildlife Conservation Society (WCS) on Oct. 26, 2020 shows Eld's deer in Keo Seima Wildlife Sanctuary in eastern Cambodia. The Wildlife Conservation Society (WCS) released a report on Monday, showing a 10-year population trend for 13 key wildlife species found in the Keo Seima Wildlife Sanctuary (KSWS), Cambodia's most biodiverse protected area. (Eleanor Briggs/WCS/Handout via Xinhua)

Photo released by the Wildlife Conservation Society (WCS) on Oct. 26, 2020 shows a yellow-cheeked crested gibbon with a baby in Keo Seima Wildlife Sanctuary in eastern Cambodia. The Wildlife Conservation Society (WCS) released a report on Monday, showing a 10-year population trend for 13 key wildlife species found in the Keo Seima Wildlife Sanctuary (KSWS), Cambodia's most biodiverse protected area. (WCS/Handout via Xinhua)

Photo released by the Wildlife Conservation Society (WCS) on Oct. 26, 2020 shows a black-shanked douc langur in Keo Seima Wildlife Sanctuary in eastern Cambodia. The Wildlife Conservation Society (WCS) released a report on Monday, showing a 10-year population trend for 13 key wildlife species found in the Keo Seima Wildlife Sanctuary (KSWS), Cambodia's most biodiverse protected area. (Eleanor Briggs/WCS/Handout via Xinhua)