Recovery of globally threatened ungulate species in Huai Kha Khaeng Wildlife Sanctuary, Thailand

Abstract

The forests of Southeast (SE) Asia support large ungulate species listed as globally threatened by the International Union for the Conservation of Nature’s Red List. In Thailand, Huai Kha Khaeng Wildlife Sanctuary (HKK) still contains the endangered banteng (Bos javanicus) and the vulnerable gaur (Bos gaurus) and sambar (Rusa unicolor). These species have been declining for decades in SE Asia. HKK is within the core area of the Western Forest Complex, one of the largest protected forest landscapes in SE Asia. This area is one of the few remaining that have the capacity to support species recovery for large ungulates and the tiger that depend on them. However, critical knowledge gaps remain on ungulate population metrics and trends of the species. In 2021, we revisited the locations surveyed in 2007–2008 and used distance sampling methodology to estimate density and abundance of banteng, gaur, and sambar. Using 32 transects in 2007, 2008 and 2021, we conducted replicated sample surveys with a total walk-efforts of 1,000 km per year and collected Distance-sampling data on target species. Banteng density increased two-fold from 0.91 ± 0.40–1.71 ± 0.79 individuals/km2, and sambar density doubled from 2.03 ± 0.51–3.99 ± 0.95 individuals/km2. In 2021, HKK supported 2,736 ± 1,264 banteng and 9,855 ± 2,347 sambar, the largest populations of these two globally threatened species in SE Asia. These results indicate evidence for recovery of large ungulate species in HKK and hope for the conservation of these globally threatened species. Our results illustrate the value of HKK as an important tiger recovery site in SE Asia, as these species are primary prey for tigers and underscore the value of ongoing efforts to eradicate poaching.