Year of the Bird: April’s Monthly Action

By eBird Northwest Team April 4, 2018
Swainson's Thrush Catharus ustulatus

What do Swainson’s Thrush, Heermann’s Gulls and Song Sparrows have in common?  Protection under the Migratory Bird Treaty Act.

April’s Monthly Action for The Year of the Bird is to draw attention to and learn about the Migratory Bird Treaty Act. The Act was ratified a century ago, however, today the Act is facing policy changes that could weaken it. The Migratory Bird Treaty Act implements international treaties with Canada, Mexico, Japan, and Russia. In the United States the Act prohibits the hunting, killing, capturing, possession, sale, transportation, and exportation of migratory birds, and their feathers, eggs and nests in the United States. With the conservation of migratory birds at its core, the Act has inspired further policies and related wildlife laws which encourage the monitoring of bird populations and create incentives for protecting birds throughout their full life-cycle.

The Migratory Bird Treaty Act was enacted at a time when poaching and overexploitation were major threats, resulting in the deaths of millions of migratory birds. Species such as the Passenger Pigeon, at one time so numerous that large flocks would darken the skies for hours as they passed overhead, were hunted to extinction by market hunters. At the same time, heron and egret rookeries were being ravaged for the plumes of the breeding birds, which then were used (along with dozens of other species) to adorn women’s hats, popular in the late 1800’s. The first international treaties, and our enacting the Migratory Bird Treaty Act in the United States recognized the intrinsic value of birds their contribution to our economy as consumers of agricultural pests, and the need for their conservation. In 1885 the Division of Economic Ornithology and Mammalogy was formed as part of the US Department of Agriculture and was devoted to the study of the positive effects of birds on agriculture. This agency was the forerunner of the US Fish and Wildlife Service and its researchers pioneered today’s concept of ecosystem services.

Today many migratory bird species face different threats including what are called “incidental” deaths from things such as oil spills, communication towers, power lines, and more. For many decades, the US Fish and Wildlife Service consistently recognized this ‘incidental take’ as a violation of the Migratory Bird Treaty Act, and held industries accountable. Over the years, when the US Fish and Wildlife Service actions were challenged, our courts have been divided on the matter. More recently, in December of 2017, Department of Interior Solicitors weighed in on the matter, deciding that incidental take is not enforceable under the Migratory Bird Treaty Act. Subsequent changes to the Act, or to its implementing regulations, may be proposed to codify this interpretation, in which case “incidental” bird deaths will no longer be considered illegal.

Migratory species can fly thousands of miles during migration, often crossing multiple international borders. The large majority of species found in the Pacific Northwest benefit from the Migratory Bird Treaty Act. One such bird, the Swainson’s Thrush, is a ’typical’ migratory songbird that migrates south after breeding and crosses many national boundaries. A look at the contrast between their breeding range throughout the northwestern United States, Alaska, and across Canada (click here to see an eBird range map for June) with their wintering range in Mexico, Venezuela, Colombia, Ecuador, and Peru illustrates the importance of international cooperation and the protections afforded by our conservation treaties and the laws that implement them (eBird range map for January).

Heermann’s Gull is another example. Also protected by the Migratory Bird Treaty Act, most of the population breeds on a single island in the Gulf of California. These birds then migrate north to winter in the United States. Other species protected by the Act are residents, and are hardly migratory. Song Sparrows, for example, may reside their entire lives within a small shrubby patch; they are, nonetheless, protected under the Migratory Bird Treaty Act because they belong to a family of birds that we share with our neighboring countries. In total, 1,027 bird species receive protection under the MBTA.

Cooperation between nations is a fundamental aspect of the bird conservation community’s efforts to protect birds and the habitats they use, not only on the breeding grounds, but on the wintering grounds and in stopover locations as well. For a century the Migratory Bird Treaty has helped connect government agencies, nongovernmental organizations, private industry, and international partners to work together conserving, protecting, and managing migratory bird populations and their habitats! Help us make this collaboration stronger during the next 100 years!

Read more about the Migratory Bird Treaty Act and the changes it is facing in these articles:


Islam, Kamal. 2002. Heermann’s Gull (Larus heermanni), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online:

Mack, Diane Evans and Wang Yong. 2000. Swainson’s Thrush (Catharus ustulatus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: