Minecraft wiki entry for Island_survival, associated text: A single chicken lays eggs, which can be thrown to get a chance to spawn a chick, which then grows into a chicken and can be bred with the first chicken to produce more.
A single sheep is your best option for creating a bed, once you find two blocks of iron ore to smelt into ingots and create shears for getting wool. Shears and a bucket are good first uses of iron. You can also use four string to craft a block of wool, but this requires killing a lot of spiders, and string should be prioritized for making a fishing rod.