illustration of migratory birds

Making the Migratory Bird Treaty Work: A Centennial Assessment

For International Migratory Bird Day, Senior Fellow and ornithologist Stan Temple spoke at the Aldo Leopold Foundation about the Migratory Bird Treaty; why it came to be, how it came to be, and what it looks like today. Below is a summary based on a transcript of the lecture that appeared in the Wisconsin Society for Ornithology’s flagship publication The Passenger Pigeon.

What was the state of bird populations c. 1900?

With essentially no regulations in place, market hunters had decimated many U.S. bird populations. By the end of the 19th century, Labrador ducks and great auks were extinct. They were soon joined by passenger pigeons, Carolina parakeets,

Illustration of the passenger pigeon

Passenger pigeon

and heath hens. The extinction of the passenger pigeon in the wild in 1902 was perhaps the single most important turning point in our national concern about the state of birds. All these avian disasters were caused by people deliberately killing birds, so the obvious solution was to protect birds from such direct sources of human-caused mortality. Similarly, birds needed undisturbed places where they would not be killed or harmed by people. The obvious solution was to protect key bird habitat as refuges. An era of “protectionism” in our approach to bird conservation was born in the early 20th century.


How did these populations become protected?

The first federal action to protect birds was the Lacey Act (1900). Rep. John Lacey justified the legislation by citing the demise of the passenger pigeon. The Lacey Act would become the first federal wildlife protection law. It ushered in an era of protectionism backed by national policies and legislation.

In spite of these nascent protection efforts, migratory birds were still being killed under circumstances that defied biological logic. Spring hunting damaged breeding populations just as they were preparing to nest. In response, Congress passed the Weeks-Mclean Migratory Bird Act in 1913, which banned spring shooting of migratory birds and declared them to be under the “custody and protection” of the federal government. However, federal courts promptly ruled the act unconstitutional for infringing on each state’s right to set hunting seasons within its borders.

Rep. Lacey, Rep. Weeks, Sen. McLean

Rep. John F. Lacey (IA), Rep. John W. Weeks (MA), and Sen. George P. McLean (CT)

Migratory birds were still vulnerable to uncoordinated and uneven state regulations because their seasonal movements took them across state lines. Eventually, the discussion in the bird conservation community and Congress coalesced around instituting a continental-scale solution that would pass legal scrutiny. In 1916 the “Convention Between The United States And Great Britain For The Protection Of Migratory Birds” achieved that vision. It became known as the Migratory Bird Treaty.

The treaty was a huge step in the right direction, but it had a curious bias of protecting some birds that were “either useful to man” or “harmless.” Other species (e.g., raptors and corvids) were left less protected and under state authority. It did, however, highlight that many birds were “in danger of extermination through lack of adequate protection,” and it recognized that migratory birds needed “uniform system of protection” across the continent. The 1918 Migratory Bird Treaty Act made the protection of migratory birds U.S. law.

With the legal protection of migratory birds in place, the remaining question was would it reverse the fortunes of species that had been decimated by overkill (i.e., by killing birds faster than they could reproduce and replace the losses). Gradually, depleted populations of many overexploited bird species made dramatic comebacks. Some, such as wood ducks and wild turkeys, have recovered to levels that can now permit well-regulated, sustainable hunting.

What new problems are today’s birds facing?

Throughout the 20th century, bird conservation efforts expanded from mere protection to research, management, and education. But the Migratory Bird Treaty remains the foundation of our efforts to protect birds from direct human-caused mortality. How well does it deal with 21st-century threats that fall into four categories?

Overkill still threatens birds when we either deliberately or inadvertently kill birds at a rate faster than they can reproduce.

Exotic species can threaten birds when we introduce them to areas outside their natural geographic ranges.

Habitat loss threatens birds when we destroy or degrade the natural habitats they depend on for their survival and reproduction.

Ecosystem stress threatens birds when we disturb ecological systems with pollution and other unnatural influences that ultimately impact birds through cascading problems within an ecosystem.

Even though we now harm birds in more ways than a century ago, direct deliberate overkill is still a problem for a few species that are killed as pests or trapped illegally for the pet bird trade. But most human-caused mortality nowadays is inadvertent which can still result in overkill.

The biggest source of inadvertent human-caused mortality is predation by feral and free-ranging domestic cats. (An estimated 2.4 billion birds are killed by cats annually in the United States.) Other sources of human-caused mortality are collisions with various human-made objects, poisoning, and industries that treat bird casualties as incidental to normal operations. The petroleum industry kills birds in oil spills and oil waste pits. Commercial fishing operations kill birds as by-catch caught in nets and hooks.

Graph showing estimated number of bird deaths and causes.

Findings and graphic from The State of the Birds Report 2014.


Does the treaty apply to inadvertent killing?

Some courts have ruled that if a person kills a bird then they are guilty of violating the Migratory Bird Treaty Act, regardless of intent. Other courts have ruled that a person must know that their actions were likely to harm a bird in order to be found guilty.  A few courts have ruled that only hunters and poachers can be convicted, as that’s what seems to some to have been intended back in 1916. With such mixed messages, expect the Supreme Court to hear one of the Migratory Bird Treaty Act cases soon.

The 2016 centenary of the signing of the Migratory Bird Treaty celebrates a long history of bird protection, but it shouldn’t be taken for granted. It is important for all those concerned about birds to stay informed as the 2018 centenary of the Migratory Bird Treaty Act and discussions of its future loom.

Join us for more illuminating Brown Bag Seminars this season!

This talk was the first in a series of Brown Bag Seminars at the foundation this season. View the calendar to see upcoming events.