Automatic Egg Farm
Version 1.27 has a new feature with chests - gathering behavior. We now can create fully automated egg farms. The flightless big birds are best suited for this idea. Plus, their cooked eggs are probably the most nutritional food in the game.
Here is a picture of a working egg farm:
To keep it simple, it's only 5 by 5 blocks inside. This keeps the water effect simple and only one water bucket is necessary. The walls may be any block.
To build it, first build the walls 5 blocks high, making an open area of 5 blocks square. Leave one space 3 blocks high, to put a door in. It should be at the corner where the chest will go. The bottom block under where the door will go has to be a type that you can place a door on. (It's diamond in this picture.) Set the door in place.
In the corner by the door, place your chest. Place one bucket of water in the corner opposite from the chest.
Place fencing just above the water level. Iron fence seems to work best. You will need 25 fence pieces.
Close the door and go to where the chest is. Break the block in front of the chest to give you access to it from outside. (Not the one the door sits on.)
It seems that Ostriches won't lay eggs on fence so only Cassowaries will work in this design. Once you have gathered some Cassowary eggs, open the door and throw them onto the fence to break them. Don't miss. If you aren't using glass, you can throw them at the wall. Hope that a lot of them spawn birds. Close the door and leave the farm.
The birds can't pass through the door, but you want to close it so wolves won't get in and eat your birds.
This farm will continue to operate as long as you don't stay too far away from it for too long. Animals will despawn if you neglect them too long. Return to the farm occasionally to collect the eggs from the chest.
Small Birds Egg Farming
To make a successful flying bird farm, make a room or other enclosure, which has to have a roof and a soft floor, away from your house (not too close) and every so often check on it. If it's too near your house birds will be too scared to lay eggs. It needs to be a large area, or the birds will get scared and try to escape. Make sure it has a high ceiling. These eggs will restore a small amount of your hunger bar. To increase nutritional value, cook the eggs. To increase the amount of birds and thus the potential egg yield, throw uncooked eggs. Take note that there can be only a limited amount of birds per farm, depending upon how big it is.
Large Egg Farming
For a successful ostrich/cassowary farm all you need is a fenced in area (with a soft floor) and it can even be near your home. These birds lay big eggs with great nutrition. To increase the amount of birds, throw uncooked eggs. You will not get a bird every time you throw an egg, but you have a chance, and you will eventually acquire more. A water stream can also be used to collect the eggs. The floor seems to be able to be made out of anything, as flightless birds do not seem to require soft floors; both birds have been observed to lay eggs on stone bricks. Using a pressure plate linked to a display like LED or a sign with message is also a recommended feature, which can help you keep track of any eggs laid.
If you cook the eggs (by placing in the furnace with a water bucket) they fill a lot more hunger than uncooked eggs and you wont need as many eggs to fill hunger. A cooked big egg will fully restore your hunger bar and will take more time to rot. But note that once you cook an egg, it is impossible to spawn birds from it. Also be careful when they are in a hot bar slot, as they can be accidentally thrown and cannot be recovered. Snowballs do more damage.