Simple thing is to have all this set up before you leave and if you come through a POE like Miami where they require an Expediter you need to have them set up to meet you upon arrival so your birds can be gotten into a freezer. Ask Duxrus about this nightmare he experienced recently. Once you know your POE you can call Customs there and ask their procedure all all are different. I stay away from Atlanta, Miami and New York and prefer Dallas, Houston, Denver and Phoenix. Never had any experience with Chicago.
I just had a client a month or so ago take a trip to South America and even with a broker his birds took 15 DAYS
to finally make it to my shop.
To my knowledge the only freezer they were put in (the cooler) was the airline freezer.....NOT USFW or USDA so no telling how long they thawed, were refrozen, thawed, refrozen...etc during those two weeks. It cost my client close to 2,000.00 in shipping and brokerage fees to have a cooler of ROTTED GOO hit my doorstep. I used every trick of the trade I knew to save them but the skin and feathers just fell right off to your touch. I hardly have any sense of smell and I could easily smell them...not good.
I would suggest just buying pen raised birds here in the states of the species you wanted to bring back. Alot of them can be purchased for 100-200$ and in perfect condition where as I have NEVER seen a fully plumed out S.A. bird that wasn't covered in pin feathers. I understand having to bring back something like a Torrent Duck but Rosey Bills, Cinny teal, Chiloe wigeon, etc...can be bought without the stress, hassle, and MONEY it would cost to "hopefully" get them back.