Hainan Black-crested Gibbon Is Headed For Extinction

Abstract

Although Hainan black-crested gibbons have been on the list of the most endangered primate species in the world for many years, their environment is still deteriorating, especially on Hainan Island. Our findings indicate that the species is unlikely to survive the next decades unless efficient conservation policies and strategies are put in place immediately. Census data show that populations of the species used to occur across the whole island, but in 2003 only 13 individuals could be found, confined to a small region, the Bawangling Natural Reserve (19 • 02 1 -19 • 08 1 N and 109 • 02 1 -109 • 13 1 E), in the western part of the island, covering only 14-16 km 2 . In other words, ca. 99% of the habitat has vanished in the past 300 years. Such dramatic change has pushed the species to the edge of extinction; only 2 groups and 2 solitary adult males, remained in 2003. Two adult females, 2 juveniles and one infant comprise Group A, in Dong'er, the core area of the western part of the reserve; and 1 adult male, 2 adult females, 1 juvenile and 1 infant formed another group (B), confined to another core area (Nanchahe) in the northern part of the reserve. The dramatic decline in the gibbon population has occurred due to vegetation reduction, ecological deterioration and extensive human impact. The forest cover was reduced from 95.5% 2000 years ago to

Social Structure and Group Dynamics of the Cao Vit Gibbon (Nomascus nasutus) in Bangliang, Jingxi, China

“…[Zhou et al, 2005;Fan and Jiang, 2009]. During the current research, 4 established Cao Vit gibbon groups included 1 adult male and 2 adult females, and these groups were stable during the 2-year study.…”

“…With increasing field data, however, multimale and multi-female groups have been reported in several species ( Hoolock hoolock [Siddiqi, 1986;Ahsan, 1995]; Hylobates lar [Brockelman et al, 1998;Sommer and Reichard, 2000]; H. pileatus [Srikosamatara and Brockelman, 1987]; Symphalangus syndactylus [Lappan 2007]; N. concolor [Fan and Jiang, 2009]; N. hainanus [Liu et al, 1989;Zhou et al, 2005]). Although bi-female groups have been reported by different researchers, groups that are stable for more than 2 years have been documented only for N. concolor [Fan and Jiang, 2009] and N. hainanus [Zhou et al, 2005]. Based on the preliminary information obtained from previous census and survey reports Chan et al, 2008;Le et al, 2008], most Cao Vit gibbons live in groups with 2 adult females.…”

Deforestation and fragmentation of natural forests in the upper Changhua watershed, Hainan, China: implications for biodiversity conservation

“…For example, the hill-partridge (Arborophila ardens), which is quite sensitive to habitat changes and can only be found in primary forests, is seriously threatened by natural forest losses (Gao 1998;BirdLife International 2010). The survival and reproduction (World Conservation Monitoring Centre 1998) and genetic diversity (Dai et al 2013) of many other species, including Madhuca hainanensis (an endangered timber species), Hainan black-crested gibbons (Nomascus hainanus) (Zhou et al 2005), Hainan Eld's deer (Cervus eldi hainanus) (Zeng et al 2005), Reevese's butterfly Lizard (Leiolepis reevesii) (Lin 2008), and other bird species (Zhou 1995), are all severely and negatively affected by deforestation. Conversion from natural forests to rubber plantation also decreased the genetic diversity of wild rice in Yunnan and Hainan (Qian et al 2001).…”

“…For example, the Hainan gibbon (N. hainanus) needs a territory size of 200-500 ha and once had a wide distribution on Hainan Island. They are currently restricted to a single narrow tropical rain forest (Bawangling Nature Reserve) (Zhou et al 2005). As Li et al (2010) showed that both fragmentation of natural forests and expansion of lowland plantation lead to hindered population rejuvenation of Hainan gibbons.…”

Proximity association in polygynous western black crested gibbons ( Nomascus concolor jingdongensis ): network structure and seasonality

“…Lappan (2007) used spatial distance to study social relationship among adults in multi-male siamang groups (S. syndactylus). Stable multi-female groups only exist in the black crested gibbon (Nomascus concolor: Jiang et al, 1999;Fan et al, 2006), Hainan gibbon (N. hainanus: Zhou et al, 2005) and Cao Vit gibbon (N. nasutus: Fan et al, 2011). Polygynous groups generally have more individuals (Jiang et al, 1994b;Fan et al, 2006;Zhou et al, 2008), and studying social relationships in such groups (e.g.…”