Migratory Bird Act

The Migratory Bird Treaty Act makes it illegal for anyone to take, possess, import, export, transport, sell, purchase, barter, or offer for sale, purchase, or barter, any migratory bird, or the parts, nests, or eggs of such a bird except under the terms of a valid permit issued pursuant to Federal regulations. The migratory bird species protected by the Act are listed in 50 CFR 10.13. For the current rule and more information click here
For an alphabetical list of MBTA protected birds click here.
The U.S. Fish and Wildlife Service has statutory authority and responsibility for enforcing the Migratory Bird Treaty Act (MBTA) (16 U.S.C. 703–712), the Fish and Wildlife Improvement Act of 1978 (16 U.S.C. 742l) and the Fish and Wildlife Act of 1956 (16 U.S.C. 742a–j). The MBTA implements Conventions between the United States and four countries (Canada, Mexico, Japan and Russia) for the protection of migratory birds.
What criteria are used to identify individual species protected by the MBTA?
A species qualifies for protection under the MBTA by meeting one or more of the following four criteria:
(1) It is covered by the Canadian Convention of 1916, as amended in 1996, by virtue of meeting the following three criteria: (a) It belongs to a family or group of species named in the Canadian Convention, as amended; (b) Specimens, photographs, videotape recordings or audiotape recordings provide convincing evidence of natural occurrence in the United States or its territories; and (c) The documentation of such records has been recognized by the AOU or other competent scientific authorities.
(2) It is covered by the Mexican Convention of 1936, as amended in 1972, by virtue of meeting the following three criteria: (a) It belongs to a family or group of species named in the Mexican Convention, as amended; (b) Specimens, photographs, videotape recordings or audiotape recordings provide convincing evidence of natural occurrence in the United States or its territories; and (c) The documentation of such records has been recognized by the AOU or other competent scientific authorities.
(3) It is listed in the annex to the Japanese Convention of 1972, as amended.
(4) It is listed in the appendix to the Russian Convention of 1976.
In accordance with the Migratory Bird Treaty Reform Act of 2004 (MBTRA) (Pub. L. No. 108-447, 118 Stat. 2809, 3071–72), we included all species native to the United States or its territories, which are those that occur as a result of natural biological or ecological processes (See 70 FR 12710, March 15, 2005). We did not include nonnative species whose occurrences in the United States are solely the result of intentional or unintentional human-assisted introduction(s).

http://www.fws.gov/migratorybirds/regulationspolicies/mbta/mbtintro.html