It's been many decades and many people on the mainlands are not interested in Donkeys anymore, in fact they are outright tired of them. Whatever profits the Pleasure Island Coachman, Staff, and Crew may have had when they sold all those donkeys all those decades ago is now outclassed by losses which are exponential to any net profits they may have made back then. To keep from going bankrupt they are going to have to sell to them other animals, and they will have to find ways to change naughty kids into animals that are not donkeys, customer demand also demands that the animals be ones with tails so if there are any animals without tails there will be no sales. It wasn't easy but the Pleasure Island Staff has found a way to make tailed humans or animals to sell to the masses to recover from their near bankruptcy.
You didn't know about it while you were on the boat with the other boys and you still don't know about it now, even though you are currently on the Island with all of the other boys, but when you misbehave on this island, you will turn into a tailed animal and when you are fully a tailed animal you will be kidnapped and sold to the highest bidder.
First you will grow a naked hairless bareskin human tail just above your Human Boy Anus, then the next step is that it will grow fur/feathers/scales on it to determine what animal you will grow into, then the fur/feathers/scales will grow over your body that will determine what you will become. Then your face will turn into a mammal/bird/reptile. What happens after this is that your clothes get destroyed leaving you naked, then your testicles will turn into ovaries. Your scrotum turn into a vulva, penis will turn into a clitoris. You will also get a vagina just below your anus meaning you will not be a human boy anymore nor will you be a mammal/bird/reptile boy either. Your navel or belly button, or bellybutton and your private parts including your, vagina and anus will turn into that of a female girl mammal/bird/reptile's.
Then you will lose your Human Mind. If it progresses a little after that, then you will be stuck like this forever. And if progresses too much after that, then you will be unable to escape and you will collapse, faint, pass out, lose consciousness, be unconscious, and be kidnapped and sold to the the highest bidder.
Also once you are seen with a mammal/bird/reptile tail just above your human boy anus meaning the changes are starting to happen to you, the Pleasure Island Staff and guards will try to kidnap you, if they succeed, You will gradually, slowly, but surely turn into a naked female girl mammal/bird/reptile and eventually be sold to the highest bidder.
If you escape the island and you get back to your home when you start changing you might turn fully back as a fully clothed human boy then again you might not. You might be a fully human boy, or a fully human boy but naked, or you might be a mostly human boy with just a mammal/bird/reptile on your butt just above your human boy anus, a furry/feathery/scaly human boy with a mammal/bird/reptile tail etc. Or you might even be a naked Female furry/feathery/scaly mammal/bird/reptile with your private parts exposed, a feral mammal/bird/reptile with your private parts exposed, or even a complete mammal/bird/reptile in both body and mind with your mammal/bird/reptile body, navel or bellybutton or belly Button, vagina, anus and tail, clothes-less, naked, nude and exposed. It all depends on how soon or late you escape the island after you begin transforming.
This is the beginning of your adventure.