These are left over relatives from the days of mining inside the park boundary... Most of which ended more than 70 years ago...
The donkey or ass, Equus africanus asinus, is a domesticated member of the Equidae or horse family. The wild ancestor of the donkey is the African wild ass, E. africanus. The donkey has been used as a working animal for at least 5000 years. There are more than 40 million donkeys in the world, mostly in underdeveloped countries, where they are used principally as draught or pack animals. Working donkeys are often associated with those living at or below subsistence levels. Small numbers of donkeys are kept for breeding or as pets in developed countries.
A Wild Jackass is a male donkey or ass, a female a jenny or jennet a young donkey is a foal. The Jack donkeys are often used to produce mules.
Asses were first domesticated around 3000 BC, or 4000 BC, probably in Egypt or Mesopotamia, and have spread around the world. They continue to fill important roles in many places today. While domesticated species are increasing in numbers, the African wild ass and another relative, the Onager, are endangered. As beasts of burden and companions, asses and donkeys have worked together with humans for millennia.