Customs paperwork for Ibex from Spain

[BGWho922]

I am getting my Gredos Ibex and Fallow deer shipped back from Spain. The cost of this was a huge surprise for me. The exporter in Spain is doing all of the paperwork on that side and shipping it air freight. I am going to drive to Dallas (about 8 hours) to pick it up in customs when it gets here to avoid any more costs. Can anyone tell me what paperwork I am going to need once I get there? I would really like to have everything in line to make it go smoothly. Thanks!