I've done it twice, two somewhat different ways. Both times froze the bird solid, wrapped in newspaper and a 12 pack soda box around the tail, taped to the newspaper.
1st one, went and bought a cooler from walmart big enough to place the bird in and checked it as a bag (taped the cooler shut) on my return flight home. TSA was intrigued to say the least, but arrived perfectly.
2nd one, I had another state to go hunt in that I was driving to before heading home, so I prepped like above and then went and bought moving boxes and bubble wrap. Wrapped the papered bird in bubble wrap, taped two boxes together to get the length needed, and shipped UPS from the UPS store 3-day select. Taxi man recommended this, and said it arrived perfectly for him to begin skinning.
Both methods get some interesting looks, but worked out for me.
