What age will the chicks be when you intend to ship them? I ask because, with newly hatched chicks- they can survive a few days in the mail without food and water since they're still absorbing their yolks. For older chicks, you'll have to figure out a way to provide them with food and water during their journey. Some people use grow gel, others use juicy fruits like oranges. And, the age of the birds you intend to ship will also determine how many you should put in your box. Obviously, you need to fill the space as much as possible with newly hatched babies. Older, fully feathered chicks can regulate their own body temperature, so packing them tightly can actually be detrimental.
And, you'll want to check your states laws as far as NPIP certifications and vet certificates go. Depending on which state you live in and the laws there, you might need to be NPIP certified to be LEGALLY correct. And, if you get caught breaking those laws, the may fine you heavily for it or make you test your flock (which could have some very negative consequences if they find something bad). If you intend to ship, you really should just have your birds tested anyway. It'll offer the buyer peace of mind and you won't have to worry about breaking any laws. Most testers don't charge that much to do it and I've even seen classes for FREE to become an NPIP tester yourself.
Good luck!
