
Shipping boxes of live birds or animals don't go on the regular conveyer belts for regular packages, so they should not get turned upside down.
The post office requires that chickens be shipped in approved shipping boxes such as one made by Horizon and they must have bio-filters on the ventilation holes. I have seen them for sale on Eggbid.com, under the 'supplies' category.
When I ship, I put a little shavings in the bottom of the box. I use little margarine cups or applesauce cups and zip tie one into the corner, I put some chicken feed in it that I have moistened with vitamin/electrolyte water, I also put some frozen peas or corn soaked in vitamin/elect water mixed in with the chicken feed - this will help keep the bird hydrated during the trip, (you can not put a dish of water in a shipping box). You can also quarter an apple and put it in there for the chicken to pick at, make sure you cut out the seeds, they are toxic.
I have shipped a number of chickens this way and they have arrived in good shape.
They have to be shipped 'Express Mail', in most cases they get there overnight, but sometimes it takes a second day. Also, if you are the one that is shipping out, you need to check on the shipping regulations to the State you are shipping to. Some require a form from your Dept of Agriculture stating you are NPIP certified Typhoid and Pullorum free, and some require a vet certification form that your chicken is healthy.
Hope I have not forgotten anything.
Hope this helps answer your questions.
Lisa