Hitting small animals with a projectile is a tricky business, especially birds. Fortunately, I got you covered.
Bullet Bows- in the late Middle Ages, many nobles, instead of using a war crossbow, used bullet bows to hunt small game. It was essentially a crossbow that fired a bullet/stone, not a bolt. Using the poison arrow code, it should be (theoretically) very simple to be able to load a crossbow with a stone (the one fired from a slingshot). The stone would do a less than a vanilla bow (~6), and would be perfect for hunting because of how cheap it is (because birds are hard to hit).
Slings- the real deal, not some puny hobbit child’s toy. Right click until maximum draw (a little slower than a Vanilla bow), and release. Stones are used as ammunition, dealing 8 damage. Morwaith hunters and Half-Trolls spawn with these. Crafted with five leather in an inverted V on vanilla table. Also crafted with any animal hide (fur, gamsbok, lion)
Please give feedback and constructive help, and my feelings will only be slightly hurt by immense criticism.