Lacey Act Amendments of 2021 This bill modifies the injurious wildlife provision of the Lacey Act, which generally prohibits the import and shipment of listed living creatures and their eggs. First, the bill specifies that the prohibition on shipment applies to interstate shipments within the continental United States. Second, the bill authorizes the Department of the Interior to issue an emergency designation prohibiting the importation of a species if necessary to address an imminent threat to human beings, to the interests of agriculture, horticulture, forestry, or to wildlife, or to the wildlife resources of the United States. Third, the bill establishes a presumptive prohibition on the importation of any nonnative species of wild mammal, wild bird, fish (including mollusks and crustacea), amphibian, or reptile, or the eggs of any such species. The presumption may be overcome if Interior determines that the species does not pose a significant risk of invasiveness to the United States.