Incidental Take of Migratory Birds No Longer Prohibited by the Migratory Bird Treaty Act

On Dec. 22, 2017, the U.S. Department of the Interior (DOI) issued Memorandum M-370501, which concludes that the Migratory Bird Treaty Act (MBTA), 16 U.S.C. § 703, does not prohibit the incidental taking of migratory birds. DOI now reads the MBTA’s prohibitions on pursuing, hunting, taking, capturing, killing or attempting to do the same as applying only to affirmative actions that have as their purpose the taking or killing of migratory birds, their nests or their eggs. The opinion is significant because it reverses DOI’s prior interpretation of the MBTA as prohibiting incidental taking or killing of migratory birds. Because the MBTA is a strict liability criminal statute, meaning that a violation can occur regardless of whether the violator acted with intent, Memorandum M-37050 is also significant because it likely will reduce potential criminal exposure on project developers and operators.

DOI previously interpreted the MBTA as prohibiting the unauthorized “incidental take” of migratory birds.2 Incidental take generally means taking that results from an activity but is not the purpose of that activity. Accordingly, DOI had concluded that the MBTA prohibited industrial or commercial activity that accidentally caused the taking of a migratory bird where there was “a close causal connection between an action and its effect of taking migratory birds.”3 (DOI had proposed to engage in rulemaking to address approaches to regulating incidental take of migratory birds, including establishment of a permitting program that would authorize incidental take.4). This interpretation resulted in enforcement actions against industries, such as oil and gas exploration and production operations, if migratory birds were killed incidentally as part of lawful operations.

However, DOI’s issuance of Memorandum M-37050 and withdrawal of its previous MBTA interpretation narrows the range of acts DOI views as prohibited under the MBTA. Beforehand, DOI viewed the potential scope of liability under the MBTA as “virtually unlimited” because the list of protected birds is long and the activities that can take protected birds are numerous. Now, “the MBTA’s prohibitions on pursuing, hunting, taking, capturing, killing, or attempting to do the same only criminalize affirmative actions that have as their purpose the taking or killing of migratory birds, their nests, or their eggs.”5 The revised interpretation should substantially reduce the actions that give rise to MBTA liability. Additionally, Memorandum M-37050 ends the need for DOI to engage in rulemaking to consider a regulatory program for the incidental taking of migratory birds.

Memorandum M-37050 likely will change DOI’s approach to reviewing projects and activities that may affect migratory birds. Additionally, it may reduce enforcement actions against industry because DOI will no longer consider migratory bird fatalities incidentally caused by industrial operations as violations of the MBTA. The memorandum conforms DOI’s interpretation of the MBTA to that adopted by the Federal Courts of Appeals for the Fifth, Eighth and Ninth Circuits.6  Whether the Second and Tenth Circuits will re-examine their more expansive views of this law in light of DOI’s new position remains uncertain.7 It is also uncertain whether the memorandum itself will be subject to judicial review.


 The Migratory Bird Treaty Act Does Not Prohibit Incidental Take, Memorandum M-37050 (Dec. 22, 2017) (available at

2 Incidental Take Prohibited Under the Migratory Bird Treaty Act, Memorandum M-37041 (Jan. 10, 2017).

3 Memorandum M-37041 at 2.

4 Proposed Rulemaking, Migratory Bird Permits; Programmatic Environmental Impact Statement, 80 Fed. Reg. 30,032 (May 26, 2015).

5 Memorandum M-37050 at 18.

6 See Memorandum M-37050 at 15-17 (citing United States v. CITGO Petroleum Corporation, 801 F.3d 477 (5th Cir. 2015); Newton County Wildlife Association v. United States Forest Service, 113 F. 3d 110 (8th Cir. 1997); Seattle Audubon Society v. Evans, 952 F.2d 297,303 (9th Cir. 1991)).

7 Memorandum M-37050 at 14-15 (citing United States v. FMC Corporation,‌ 572 F.2d 902 (2d Cir. 1978); United States v. Apollo Energies, Inc., 611 F.3d 679 (10th Cir. 2010).

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