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The overarching aims of the project were to estimate
population size of saiga antelope with associated confidence
intervals across its entire range in western Mongolia, and to
conduct spatial modelling on the survey data to assess the human
and environmental factors influencing the distribution of the
saiga.
Access the report here: Western Mongolian
Population Assessment
In order to describe the population dynamics of the saiga antelope adequately, a discreet time, stochastic age-structured model is needed. Management strategies investigated are: taking a proportion of the population or a constant number of individuals; selecting the individuals killed by age and sex or harvesting in the proportions found in the population; harvesting every year, every other year or only in years with a good climate. These options are chosen with reference to the management strategies that were in place before the collapse of the Soviet Union.
Satellite tracking of gazelles proved their ability to move long distances and provided details of their migration routes. In Omnogobi, the NDVI of the summer range was higher than those of annual and winter ranges during summer, but from October to November the NDVI of the summer range was lower than annual or winter ranges. The shift in NDVI values between summer and winter ranges corresponded with seasonal migrations of gazelles.
Despite the potential effects of numerous sex-skewed harvests, in this paper we investigate one potentially deleterious effect of sex-skewed harvests. Both theory and experimental data suggest that male ungulates are limited in their absolute ability to inseminate females.
Using a Leslie-Matrix model and published data on impala, we show that the interaction between sperm limitation and harvests with highly male-biased sex ratios can lead to greatly reduced female fecundity (defined as the number of young born) and population collapse. These results are robust and suggest that present methods of harvesting may not be optimal or viable in the long term.
The battle over access to mates is perhaps one of the most extreme conflicts in evolution. Male to male conflict sometimes becomes so intense that it can result in the death of all males in a population. For example, in marsupials of the genera Antechinus and Dasyurus, the diseases that appear to follow from excessive investment in mating can wipe out all males in the population after the mating season. This is not harmful to population persistence, however, as inseminated females produce new males. If males can invest so much in sex that they eventually kill themselves, to what extent will they harm a potential mate?
The optimal hunting mortality rate and proportion of adult males in the harvest are found as functions of the size and structure of the saiga population before hunting. The effects of stochastic climatic variation on the population are taken into account in this model. It is shown that key assumptions must be made about the effects of the breeding sex ratio on female fecundity, and about whether poaching is occurring. If incorrect assumptions are made about either of these factors, the calculated optimal strategy can become severely suboptimal. A simple suboptimal decision rule that takes the population size and structure into account is shown to be more able to buffer against these factors…
Saiga tatarica is a member of the family Bovidae, and is native to Eurasia. It roams in herds from the lower reaches of the Volga River in Kazakhstan and Zungaria; and some are present in Mongolia. Because of near extinction due to hunting, the animal has been protected since 1920.