We went there in the rainy season. the water level were tremendously high. Even some villages and roads were sunk under water at that time.
At the time when we went there, there was no land route connecting to the island, but people were saying that in winter times, a land route does opens up.
But having said that, I would suggest you to go via boat, It will only cost you 500rs from behli bathar village(Dadyal).
People were very nice in that area.
For me the trek which we took from the boat's dock to the fort is enough
We did saw livestock in the fort aswell and I seriously doubt that people would bother much to take donkeys to the fort by a boat. I think the thekedar(so called) brought these animals to the island for his routines.