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Many terrestrial mammalian species aggregate to give birth. Such aggregations are likely to be a response to changing resource and water availability, for predator swamping and avoidance of disturbance. The critically endangered saiga antelope (Saiga tatarica) is one such species. We analysed spatio-temporal locations of saiga calving aggregations in Kazakhstan over the last four decades obtained from aerial and ground surveys, to identify the factors determining the selection of calving sites within the species’ range as well as any changes in these locations over time. Generalized mixed models were employed in a use – availability framework to assess the factors distinguishing calving from random sites and predict suitable areas for calving. Saigas selected sites, with lower than average productivity and low year to year variability in productivity, at an intermediate distance from water sources, and away from human settlements. A significant change in calving locations was observed during the last decade, with calving areas occurring further north and further away from settlements than previously. The results demonstrate that the choice of calving areas is largely driven by environmental factors. However, disturbance also has a significant impact on calving site selection and in recent decades, its influence overrides that of environmental factors. This increase in the influence of disturbance coincides with a precipitous decline in saiga numbers due to poaching, as well as substantial reductions in the intensity of land use for livestock grazing following the breakup of the Soviet Union. Predictive models based on such studies can improve species conservation by guiding the stratification of sampling for effective monitoring and deployment of rangers to protect the females at this critical time.

Aim Long-distance migrations of terrestrial animals, driven by needs such as food, water and escaping predators and harsh climatic conditions, are widely known phenomena. The saiga antelope (Saiga tatarica tatarica) migrates over long distances in the semi-arid rangelands of Central Asia. Both the saiga's range and its populations have been severely affected by socio-political and land use changes over the last century, related to the formation and dissolution of the Soviet Union. We identified ecological drivers of saiga migration, compared four populations in terms of differences in the geographical characteristics of their ranges and the factors affecting habitat selection within the seasonal ranges. Location Kazakhstan and pre-Caspian Russia. Methods Using 40 years of direct observations, we tested for differences between the four saiga populations' ranges in terms of precipitation, seasonal productivity and topographical variables using discriminant analyses. We tested hypotheses concerning the drivers of migration to their seasonal ranges and assessed the impact of peak and average values and the predictability of drivers of habitat use within the seasonal ranges using logistic regressions. Results Three of the four populations migrate in a similar way, following a latitudinal gradient driven by seasonal changes in productivity, which is closely related to broad-scale differences in precipitation. Intermediate productivity and its low interannual variability determine habitat selection within the seasonal ranges of all the populations. Main conclusions Migration of all four populations is driven by productivity and precipitation. The migrations in Kazakhstan are still intact despite major recent disruption to the populations, whereas their status in the pre-Caspian region is unknown. All four populations are under severe threat from habitat loss, poaching, lack of protection and gaps in ecological knowledge. A better understanding of the drivers of saiga migration at multiple scales is a key step towards addressing these threats.

Effective conservation requires a good understanding of factors causing variation in population growth rate. We here analyse the relationship between female age and fecundity in the saiga antelope Saiga tatarica tatarica, a critically endangered ungulate of the Eurasian steppes and semideserts, at both individual and population levels. Annual variation in age structure and twinning rates was investigated using long-term datasets, sampling a total of 3308 females in four populations over more than 40 years. Further, a new non-invasive method is presented, estimating twinning rates from both calves and placentas encountered during calving aggregation transects. At an individual level, the most parsimonious model for twinning rates included three age classes (1, 2 and ≥3 years); however, the model with only two classes (1 and ≥2 years) was competitive and particularly useful for monitoring because these two age classes can reliably be determined by direct observation in the field. Among yearlings, 77.4% were fecund and 11.7% twinned, whereas among older females 94.6% were fecund and 72.6% twinned. At a population level, annual variation in age structure (proportion ≥2 years) correlated well with annual variation in twinning rate except in the north-west Pre-Caspian population. Our results suggest that the recent poaching-driven collapse in saiga numbers has potentially resulted in reductions in fecundity, which will have an impact on population growth rate. Our results highlight the potential for monitoring of twinning rate using non-invasive calving aggregation transects as a cost-effective additional tool to population counts for monitoring the status of this critically endangered species. These monitoring methods are also potentially transferable to other ungulate species.

We analysed the mtDNA control region (HV1) of 93 tissue samples from all five populations of the saiga antelope Saiga tatarica. The results show a slight but clear distinction between S. t. mongolica and S. t. tatarica, supporting the current designation of S. t. mongolica as a subspecies rather than a separate species. Levels of genetic diversity were low in S. t. mongolica, consistent with the small size of its population and long isolation. Although populations of S. t. tatarica have reasonable levels of genetic diversity, their conservation status is perilous. The Kalmykian and Kazakhstan samples each contained unique haplotypes, although the species as a whole appears polyphyletic, consistent with recent fragmentation and rapid population decline. An understanding of the population genetics of this species is an essential prerequisite for conservation action.

The ecology and management of the Saiga antelope Saiga tatarica tatarica, a nomadic herding species of the desert, semi-desert and steppe ecosystems of Central Asia, are reviewed. The range area and population size of the Saiga in Kazakhstan have changed substantially since they were first described, declining rapidly through the nineteenth century to a low point in the 1920s, followed by recovery until the 1950s and subsequent stabilization. A detailed description is given of the Saiga’s habitat and the differences between the winter and summer pastures. The species feeds mainly on grasses, although herbs and shrubs are seasonally important. The migratory patterns of the species divide into directional seasonal migrations and less structured local movements. Group sizes are largest in the calving season and during the autumn migration. Harems are formed in early December. Fertility rates are high, with females giving birth in their first year of life, and routinely twinning thereafter. However, mortality rates are also high in years of drought and harsh winters. The major factors limiting populations include climate, parasites and diseases, predators, and anthropogenic factors. The major human influences are commercial hunting and poaching. Agriculture and habitat alteration are less important currently, although they were probably responsible for the division of the Kazakhstan population into three separate populations. The species was well managed in the Soviet period, with strong institutional structures. However, a new political era requires a re-evaluation of the Saiga’s needs, in the face of a growing threat from poaching.

Effective conservation decision-making requires robust estimates of population trends. It is often assumed that, as long as monitoring methods remain consistent over time, trends in relative abundance are valid proxies for actual abundance. However, if the bias and uncertainty of relative abundance estimates change over time, this can have a serious impact on the validity of monitoring programmes. We developed a simple model for the retrospective assessment of the likely error and bias in abundance estimates from aerial surveys of the saiga antelope. Due to dramatic reductions in group size and density, current estimates of abundance are probably substantially lower than the true population size, and the level of uncertainty surrounding these estimates precludes their use for monitoring trends. This has implications for the Government of Kazakhstan's ability to monitor progress towards their agreed conservation goals. The method is potentially widely applicable to species for which historical data on relative abundance and group size are available. © Inter-Reaserch 2009.

A common assumption is that breeding in polygnous systems is not limited by the number of males because one male can inseminate many females1,2. But here we show that reproductive collapse in the critically endangered saiga antelope (Saiga tatarica tatarica) is likely to have been caused by a catastrophic drop in the number of adult males in this harem-breeding ungulate, probably due to selective poaching for their horns. Fecundity and calf survival are known to be affected by markedly skewed sex ratios3, but in the saiga antelope the sex ratio has become so distorted as to lead to a drastic decline in the number of pregnancies — a finding that has implications both for the conservation of the species and for understanding the reproductive ecology of polygynous ungulates.

We present new data on the size of all the saiga antelope populations; three populations of the subspecies Saiga tatarica tatarica in Kazakhstan, one of S. t. tatarica in Kalmykia, Russia, and two of S. t. mongolica in Mongolia. The data suggest that three populations are under severe threat from poaching and have been declining at an increasing rate for the last 2–3 years. The Ustiurt population in Kazakhstan was relatively secure but is now also under threat. There is evidence of much reduced conception rates in Kalmykia, probably because of selective hunting of adult males. The Mongolian subspecies shows no evidence of recent decline, but is of concern because of the population's small size. The cause of the population declines appears to be poaching for meat and horns, which is a result of economic collapse in the rural areas of Kazakhstan and Kalmykia. We suggest that full aerial surveys be carried out on the Betpak-dala (Kazakhstan) and Mongolian populations, and that funding is urgently required for the control of poaching in all parts of the saiga range.