Did the Foundation send enough Przewalski Horses to Hustai?
In 1992 the first transport took place, followed by four consecutive transports. In total a number of 84 Przewalski horses arrived at Hustai National Park. Five shipments were needed for building up a solid base population in a relatively short time.
We now know that the toughest period for the newly arrived Przewalski horses lies in the first year after their arrival. In the year of their arrival 22% have perished. The stressful transport, getting accustomed to a new group and the adaptation to a fickle and merciless climate all take their toll. If an animal bears the test of the first year, then the better its chances are to survive and manage without outside help. Seventy-one percent of the present 150 Przewalski horses at Hustai were actually born there; a good sign. The wild-born takhi (as the Mongolians call their wild horse) are better accustomed to the harsh environment than their imported parents are.
Fertility is prolific. Eighty-four percent of the mares of three years and older received a foal. The average percentage of foals that have died since 1993 is 31%. In 2001 and 2002 the average mortality rate among foals lowered to respectively 25% and 22%. With regard to the same period the mortality among yearlings is lowest (1.5%). Stallions older than two years are having a much harder time, than their female peers do. The average mortality rate for stallions in this age class is 8.7%, whereas that of the mares is 7.2%. The mutual competition between harem stallions and the confrontations of harem stallions with the bachelors asks not only much of the animals' endurance, it also afflicts injuries. Inflammation can be fatal.
Until now the annual growth of the population at Hustai National has been strongly influenced by the introductions from the Netherlands. Nevertheless, even without the stimulus of these imports, we believe this population will be capable of multiplying itself by an approximate of 8 to 10% each year.
Age distribution plays a significant role in these prognoses. Half of the present population is under five. The contingent of animals that will effectively take part in the reproduction process has increased considerably. The number of prolific mares, in the range of three years and older has increased to 48, which means that more foals will be born in the oncoming years.
Ageing of the population, including a rising mortality rate, is out of the question. Only a mere 15% of the Przewalski population at Hustai belongs to the age group in-between the ages of ten and sixteen. Mares in this age group are still capable of foaling, albeit not as often as younger mares can. Therefore, we do not expect increased mortality numbers as result of an ageing population. On the basis of the numbers of stallions and mares in the different age groups, as well as the average birth and mortality rate within these groups we are able to predict a possible growth of the population to approximately 150 animals in 2003. We are happy that this prediction has come true. The age structure of the expected population is in balance and so will the distribution of the sexes. Starting from this prognosis we can justify our optimism for the near future and our decision to stop the imports from the Netherlands.
Hopefully this growth of 8 to 10% per annum will continue for at least a few decades. Only if the population has increased to a number of 500 Przewalski horses and lasting protection of the National Park is guaranteed then their future here will be fully ascertained. The introduction programme at Hustai National Park will have reached its goal. The emphasis of the Foundation's involvement will be put on the sustainable protection of this population in Hustai National Park.