The Asiatic wild ass Equus hemionus, or khulan, once ranged across much of Central Asia, but is now globally threatened. The largest free-ranging populations are now restricted to a 250-km wide area (range 100±400 km) across the Gobi Desert region of southern Mongolia. Over the last 23 years the population has moved further north and east into its former range. Surveys conducted in the 1970s and 1980s estimated that the Mongolian population contained fewer than 15 000 animals and was declining as a result of human exploitation and livestock competition. Aerial surveys (one in autumn 1994, two in spring 1997) were¯own as line transects over portions of the khulan's range in Mongolia and ground surveys (®ve in spring, summer, and autumn 1994±97) were conducted by vehicle and foot. Sample sizes and areas surveyed were larger than previous surveys, and our methods were often more systematic. Population size was estimated at 33 000±63 000 wild asses in Mongolia. Animal density ranged from 4.2 1.3 to 19.1 3.2 per 100 km 2 . Mean group size ranged from four to 35 animals in the south-western Gobi, four to seven animals in the southern Gobi, and three to 18 in the south-eastern Gobi. Our data suggest that Mongolia is the most important stronghold for the conservation of E. hemionus. Conservation management continues to be challenging because intensive studies on khulan biology and ecology are just beginning. As a freemarket economy continues to emerge in Mongolia, pressure from resource extraction interests and nomadic livestock herders to remove the khulan's protected status, permit harvesting and halt population growth and expansion, also makes implementation of research and conservation management programs more imperative.

Despite 150 years of interest in the ecology of dinosaurs, mammoths, proto-hominids and other extinct vertebrates, a general framework to recreate patterns of sociality has been elusive. Based on our recent discovery of a contemporary heterospecific mass death assemblage in the Gobi Desert (Mongolia), we fit predictions about gender-specific associations and group living in extant ungulates to extinct ones. We relied on comparative data on sex-ratio variation and body-size dimorphism, basing analyses on 38 additional mass mortality sites from Asia, Africa, Europe and North America that span 50 million years. Both extant and extinct species died in aggregations with biased adult sex ratios, but the skew (from 1:1) was greater for extinct dimorphic taxa, suggesting that sociality in these extinct species can be predicted from spatial and demographic traits of extant ones. However, extinct rhinos, horses and zebras were inconsistent with predictions about adult sex ratios, which underscores the inherent difficulty in backcasting historic patterns to some monomorphic taxa. These findings shed light not only on the sociality of extinct species but provide a sound, although limited, footing for interpretation of modern death assemblages within the context of the emerging science of taphonomy and palaeobehaviour.

Data are presented on the changes in distribution and abundance of the Mongolian saiga Saiga tatarica mongolica in the last few decades, based on an analysis of the literature and the authors’ field observations. The subspecies has suffered a considerable decline in its range because of hunting and competition with domesticated stock. In 1997 a survey was made of almost all the known range, which consists of two disjunct areas and covers a total of 2200 sq km. A total of 609 animals was recorded and analysis of the census results suggests that c. 1300 saiga remain in total. The authors recommend strengthening the nature reserve established in 1993 in the Shargyn Gobi, and creating several sanctuaries outside this area, where Mongolian saiga from the main remaining population could be reintroduced. These measures would enhance prospects for the survival of this endemic subspecies of the semi‐deserts of western Mongolia.

authors recommend strengthening the nature reserve Abstract Data are presented on the changes in distriestablished in 1993 in the Shargyn Gobi, and creating bution and abundance of the Mongolian saiga Saiga several sanctuaries outside this area, where Mongolian tatarica mongolica in the last few decades, based on an saiga from the main remaining population could be analysis of the literature and the authors' field obserreintroduced. These measures would enhance prospects vations. The subspecies has suffered a considerable for the survival of this endemic subspecies of the semidecline in its range because of hunting and competition deserts of western Mongolia. with domesticated stock. In 1997 a survey was made of almost all the known range, which consists of two