To apply these principles, we return to the language of 18 U.S.C. ?? 42(c): ???[I]t shall be unlawful for any person, including any importer, knowingly to cause or permit any wild animal or bird to be transported to the United States ?????? under inhumane or unhealthful conditions??????????? For much the same reasons that a simple review of the language of ?? 42(c) indicates that ???knowingly??? a