Range Expansion as a Response to Increasing Group Size in the Yunnan Snub-Nosed Monkey

Abstract

The Yunnan snub-nosed monkey (Rhinopithecus bieti) is characterized by a larger home range and group size than other colobine species. We investigated variations in home range size of a free-ranging group of R. bieti from 1998 to 2007 in the Baimaxueshan National Nature Reserve in Yunnan, China. Group size increased from 160 to 450 over the 10 years. Results also showed a home range shift and yearly home range expansion, although this expansion was very limited. The study group covered a 33.78-km² area during the 10-year period, with some areas abandoned and others used repeatedly. The yearly home range increase stopped in 2004 and decreased thereafter. Despite increasing group size usually being coupled with larger yearly home range (>30 km²), the group confined itself within a relatively small and stable area (<18 km²) during 2005–2007, with a significant portion of their accessible home range discarded. Consequently, the study group showed the highest recorded population density among extant groups of R. bieti. Reasons why the group settled into a substantially smaller home range area remain unclear.

神农架两个大小不同的川金丝猴群的家域变化：对食物竞争的启示

“…However, detailed data on the availability and distribution of both lichen and plant foods are still lacking for most populations of the two species. There is increasing evidence showing that intragroup feeding competition in these two species may be more significant than previously hypothesized; for example, several indices of foraging efforts increase with group size, including home range size (Li et al, 2010; this study), daily travel distance (Grueter & van Schaik, 2010), and time allocated for feeding and moving (Liu et al, 2013a).…”

“…Knowledge on the home range size of a species or population is of great importance for understanding its behavioral and social ecology (Isbell, 1991; Snaith & Chapman, 2007; Zhou et al, 2007) and for improving the effectiveness of conservation strategies (Bryant et al, 2017; Huang et al, 2017). The home range size of non-human primates (hereafter, primates) is influenced by a range of ecological and behavioral factors, including food availability and distribution (Curtis & Zaramody, 1998; Zhang et al, 2014; Zhou et al, 2007), group size (Dias & Strier, 2003; Gillespie & Chapman, 2001; Li et al, 2010), sleeping site location (Zhou et al, 2011), water availability (Scholz & Kappeler, 2004), parasite avoidance (Freeland, 1980), topography (Fan & Jiang, 2008), and intergroup relationships (Benadi et al, 2008).…”

“…The influence of group size on home range size has also been widely investigated, but with contradictory findings; home range size increases with group size in many species and populations (Dias & Strier, 2003; Fashing et al, 2007; Gillespie & Chapman, 2001; Kurihara & Hanya, 2015; Li et al, 2010; Teichroeb & Sicotte, 2009), but not in all (Struhsaker, 1975; Whitesides, 1989). Theoretically, when food resources are limited, the addition of feeding members should reduce the amount of food intake per capita and thus larger groups are expected to occupy larger home ranges to obtain adequate food for all group members (Chapman & Chapman, 2000a; Isbell, 1991; Janson & van Schaik, 1988).…”

Reproductive Parameters of Wild Rhinopithecus bieti

“…The endangered Yunnan snub-nosed monkey (Rhinopithecus bieti) lives in the eastern Himalayan highlands, bounded by the upper Yangtze River and Mekong Rivers [Long et al, 1994;Xiao et al, 2003;Li et al, 2010;Huang et al, 2012]. R. bieti is characterized by a multilevel society [Kirkpatrick et al, 1998;Kirkpatrick and Grueter, 2010;Ren et al, 2012], that is composed of 5-41 breeding units (one-male units, OMUs) and 1 or more all-male units (AMUs) [Grueter and Zinner, 2004;Ren et al, 2012;Grueter, 2013].…”

Impact of Snow Storms on Habitat and Death of Yunnan Snub-Nosed Monkeys in the Baimaxueshan Nature Reserve, Yunnan, China

“…The main goals of this study were to (1) assess the damage caused by the snow storms to vegetation for different types of terrains; (2) investigate the dead individual of the two large monkey groups after the snow storms; (3) examine the ecological adaptability of R. bieti in response to natural disasters. [16] and the Xiangguqing group consisting of 480 individuals [17]. The monkeys range from elevations from 2600 m to 4000 m. The habitat consists of a mosaic of various primary and secondary vegetation zones, including mixed coniferous and deciduous broadleaf forest, highelevation Abies forest, evergreen oak forests, pine forest, and cattle pastures.…”