Donkeys were introduced in the 17th century by the spaniards. They were brought along to do the heavy work. Once modern transport came around they were of no use anymore to the people. The donkeys were set free to roam around the island with no one specifically taking care of them.
Bonaire is a harsh environment for donkeys. With our dry climate donkeys find it hard to find food, thus, any (young) juicy leaves are a treat for a donkey and so can be your garbage! But this is exactly why young trees have a difficult time growing up in Bonaire if not fenced properly away from donkeys and goats.
Donkeys also have to face our traffic. Cars can hit a donkey easily in the dark and hurt them. We cannot blame the donkeys they were brought to Bonaire and thus we all have to take care of them.