(Picture added by Stanimus on SC Wiki)
|Donkey can jump single fences|
Using Your WhistleAlthough the whistle is a helpful tool in Survivalcraft, you need to remember that your horses, donkeys, and camels will only come to you if you are within a 30 block range. So it is not a good idea to allow your saddled animals to wander about, thinking you can summon them with a whistle. It is a good idea to keep your animals in a double fence, and keep the whistle just for emergencies, etc. if you fall off of your horse, and it continues to run, you can summon it again. Using the whistle will also make cows and bulls run away.
More animal tips on SC Wiki Tips page: http://survivalcraftgame.wikia.com/wiki/Tips%2C_Tricks%2C_and_Common_Mistakes