People do not always agree on what type of nesting material is best for birds. I like to give my Zebra Finches small strands of burlap and shredded Kleenex tissue to use for nesting material. It is important to make sure that what you give them is not so fine that they can get it tangled around their legs or around the chicks. Birds can die if they become badly entangled in the nesting material. Eggs usually are laid at the rate of one per day.
Incubation starts after the last egg is laid, and the eggs start hatching about thirteen days later.
Zebra Finches can lay between one and eight eggs, but most nests have between two and five eggs on average. The female does most of the incubating but the male will also take his turn on the eggs to give the female a chance to stretch, eat, and drink. If the eggs are fertile, they will turn a darker color after the first week. If you cannot tell buy looking at the eggs whether or not they are fertile, you can candle them. Candling eggs is really pretty simple but if you are very nervous about it, do not attempt it.