No abstract

We develop a time budget model for the hylobatid family with the aim of assessing the extent to which their contemporary and historical biogeographic distributions might be explained by ecological constraints. The model uses local climate to predict time budgets, and from this the limiting size of social group that animals could manage at a given location. The model predicts maximum group sizes that vary between 3 and 15 within the taxon's current distribution, indicating that the combination of their dietary and locomotor styles with the kinds of habitats they inhabit radically constrain group size. Beyond the edges of their current distribution, sustainable group size rapidly tends to zero, although if they had been able to bypass some of these areas, they would have found very suitable habitats in southern India and beyond the Wallace Line. While travel time would be a major constraint on group size at larger group sizes, as it is in great apes, the main factor limiting the gibbon's current distribution is the time they need to spend resting that is imposed on them by the environment. The model also indicates that gibbons would not now be able to survive in regions of central and southeastern China where they are known to have occurred within historical times, perhaps because historical climate change following the Little Ice Age of the C18th made these regions uninhabitable for them. Finally, our results indicate that gibbons have the ecological capacity to live in larger groups than they do, making it unlikely that their adoption of monogamy reflects purely ecological constraints.

Elevational and latitudinal patterns of mismatched with species richness in Gaoligongshan species richness for birds and mammals were compared Region, while there is a better fit between the two in Jingdong County. In both areas, however, it ap-with human population density in relation to nature reserve designation in two areas of Yunnan Province, peared that reserves were located primarily in order to reduce conflict with humans rather than to maximize China. Results suggest that species richness is not the same for the two areas. In Gaoligongshan Region, conservation of biodiversity, probably because humans were responsible for forest -especially primary species richness is inversely correlated with elevation and forest -destruction and degradation in the low-lying altitude, while reserve designation is positively corareas. related with elevation and latitude. In Jingdong County, reserve designations are positively correlated with elevation, but species richness shows no clear trends. In

Elevational and latitudinal patterns of species richness for birds and mammals were compared with human population density in relation to nature reserve designation in two areas of Yunnan Province, China. Results suggest that species richness is not the same for the two areas. In Gaoligongshan Region, species richness is inversely correlated with elevation and altitude, while reserve designation is positively correlated with elevation and latitude. In Jingdong County, reserve designations are positively correlated with elevation, but species richness shows no clear trends. In general, the present situation is strongly influenced by human activities. It appears that reserve designation is mismatched with species richness in Gaoligongshan Region, while there is a better fit between the two in Jingdong County. In both areas, however, it appeared that reserves were located primarily in order to reduce conflict with humans rather than to maximize conservation of biodiversity, probably because humans were responsible for forest—especially primary forest—destruction and degradation in the low‐lying areas.

We estimate that roughly one-third of Gaoligongshan's total area is now devoted exclusively to agriculture and other uses that preclude maintenance of biodiversity. In most cases, primary forests existing at the establishment of the three Nature Reserves have been conserved effectively. However, small-scale (but largely unmonitored and uncontrolled) tree-felling and other vegetation disturbance continues in many areas. Despite these lapses, forests are in better condition within, than outside of, established Nature Reserves. As well, the future for these forests looks brighter than for those surviving outside Reserves: at the very least, county governments are not free to convert them into pine plantations.In contrast, hunting has been reduced only slightly — much less effectively than forest cutting has been. Although it is possible to find evidence of persistence of some rare animal species, and some Nature Reserve personnel believe there are indications that sensitive and rare species are showing an upward trend, poaching of animals is still common, particularly of smaller-bodied or lesser-known species. Although it seems well established that wellknown species (e.g. Takin) must be strictly protected, many species at equal or greater risk of extirpation and equally protected legally (e.g. some species of pheasants), do not enjoy such effective protection.