Recommend that you should install Just Enough Items (for mods using Forge) or Roughly Enough Items (for mods using Fabric) to view the full recipes included in this mod.
Bird Meat
Bird Meat is dropped by all of the birds. Just place the raw meat in a furnace to cook yourself some tasty grub!
Book of Birds
This book tells you about all of the birds in game. It includes their picture, the scientific name and a little caption about them. It can be crafted using a normal book and a peacock feather, like so:

It starts off blank, so you will need to find the birds and left click them with the book to log them. This will reward you with xp.
Eggs
Eggs can be found in two ways: collected from nests, or laid by birds. All eggs have a 10% chance of spawning a chick when thrown. This can be increased up to 50% by crafting the eggs with blaze powder, adding 20% each time. Any attempt to increase after 50% will consume the powder, but not increase the chance.

There are also unidentifed eggs. These are black with a question mark on them. To indentify these, you must use the egg sorter.
Eggshell
This item will occasionally drop from nests, and also when you throw any of the bird eggs. It can be used like bonemeal to speed up the growth of plants and to grow flowers.
Egg Sorter
It can be crafted using the following recipe:

Placing unidentified eggs in the top slot and redstone dust in the bottom will result in the eggs being identified. This is not always successful and may produce eggshells.
Nests
Probably the most important part of the mod. You will find these nests sitting atop leaves in your world. Breaking them will drop 0-3 different bird eggs and some sticks. Empty nests can be crafted using the following recipe.

You may right click on the nests to open the GUI.
Peacock Feather
Dropped by peacocks, these feathers can be used to craft the Book of Birds.
Phoenix Dust
This dust is used to create a phoenix egg. It can be found as a rare item in abandoned mineshaft chests. One is dropped by a phoenix upon death.
Phoenix Egg
Phoenix eggs are used to hatch the mythical phoenix. They require a light level of 9, 10 or 11 to hatch (a flame particle effect will appear when the light level is suitable). These can be found as a rare item in a monster dungeon, extremely rarely found in nests, or crafted by surrounding a chicken egg in phoenix dust.

Phoenix Feather
Dropped by a phoenix upon death. This feather does not yet do anything.