Volume 26, Number 2 February 23, 2018

DOI Reverses Opinion – Migratory Bird Treaty Act Does NOT Prohibit Incidental Take

The Department of the Interior (DOI) recently released M-37050: The Migratory Bird Treaty Act Does Not Prohibit Incidental Take, formally defining its position that the penalties for pursuing, hunting, taking, capturing, killing, or attempting to do the same apply only to intentional actions, and do NOT apply to incidental or accidental take of migratory birds.  M-37050 permanently withdraws and replaces M-37041 Incidental Take Prohibited Under the Migratory Bird Treaty Act, which means project developers no longer face the threat of prosecution for accidentally killing migratory birds during tree-clearing or construction.

DOI is effectively stating that there is no legal standing to prosecute incidental take under the MBTA, and is requiring the U.S. Fish & Wildlife Service (USFWS) to stop regulating incidental take of migratory birds.  In addition to removing the threat of prosecution for incidental take, this change allows project developers to avoid the delays typically associated with avoiding migratory birds and their nests, such as time of year restrictions on tree clearing.  By issuing this opinion, DOI clarifies the position of the current Administration that “Interpreting the MBTA to criminalize incidental takings raises serious due process concerns and is contrary to the fundamental principle that ambiguity in criminal statutes must be resolved in favor of defendants.” 

Note that both the current M-37050 and prior M-37041 are interpretations of the same United States Federal Law defined in Title 16 of the United States Code, sections 703-712 – therefore these interpretations are only policy, not law.  Enforcement of MBTA policy has historically been scattered, with no uniform enforcement for incidental take or time of year restrictions.

History and Intent of Migratory Bird Protections

As the MBTA evolved from the Lacey Act of 1900, to the Weeks-McLean Law, then the Migratory Bird Treaty Act of 1918, and finally through several variations to its current state today, the issue of incidental take under these agreements has been the subject of debate and of dissenting opinions throughout Circuit Courts and Courts of Appeals.  In support of its current opinion, the DOI memo cites the historical context and original intent of the treaty at the turn of the 19th century – which was to protect migratory bird populations from being devastated by commercial hunting.

In addition to discussing this history, the DOI memo also lays out further support for a limited interpretation of MBTA, identifies the Constitutional problems that arise from attempting to enforce vague laws, and highlights the potentially unlimited scope of liability that would accompany broader interpretation of the treaty.  For example – according to the USFWS, cats are the “top human-caused threat to birds”, killing an estimated 2.4 billion birds per year.  A broad interpretation of the MBTA that lumps incidental take together with the intentional and purposeful take of migratory birds that the treaty prohibits, has the potential to turn cat-owners into criminals by making such feline incidental take a misdemeanor crime! 

Questions about the MBTA?

Stay tuned for updates as we follow the implementation of this opinion throughout related agencies such as the USFWS!  For questions about the MBTA and how it may affect your projects, please contact Ben Rosner in Virginia or Mike Klebasko in Maryland.

Robins are one of many species protected by the MBTA
photo credit: American Robin (Turdus migratorius) by mdf via Wikimedia Commons

Check out past issues in the Field Notes Archive.


  • Ben Rosner

    Gainesville, VA

  • Mike Klebasko

    Millersville, MD