Duc Le, of Garden Grove, entered the plea in federal court Monday. The 34-year-old man faces up to five years in prison when he is sentenced in June.
Co-defendant Sony Dong pleaded guilty last year to illegally importing wildlife after authorities discovered 14 songbirds strapped to his legs on a flight from Vietnam to Los Angeles.
Authorities say the birds could have sold for up to $400 each. The birds survived the trip.
Le was arrested after investigators found 51 songbirds at his home.
Dong faces up to 20 years in prison when he is sentenced April 26.
