19 CFR 12.27: Importation or exportation of wild animals or birds, or the dead bodies thereof illegally captured or killed, etc.

Customs officers shall perform all duties required of them under statutory provisions that prohibit or restrict the importation or exportation of wild animals or birds, or the dead bodies thereof, or the eggs of such birds, killed, captured, taken, transported, etc., contrary to law. Such laws and statutory provisions include 18 U.S.C. 43, 44, 3054, 3112.