One hundred years ago today, the United States and Canada signed a landmark treaty to protect birds flying across international borders. The Migratory Bird Treaty highlighted the accelerating extinction of over-hunted species, leading to pivotal environmental legislation in North America. To implement the treaty’s tenets—banning the hunting of all insectivorous birds and regulating hunting seasons for game birds—Congress passed the Migratory Bird Treaty Act (MBTA) two years later in 1918. The MBTA has since saved millions of birds, and marks one of the National Audubon Society’s earliest successes and milestones.

Over its long and storied lifespan, the MBTA has surged to the forefront of global conservation via treaties with Mexico, Japan, and Russia. The law has also broadened its coverage to include birds such as eagles, owls, and corvids. Now, a total of 1,026 species are protected, including avians that don't actually migrate. But the act needs to be revamped for the 21st century; millions of birds still die each year from collisions with power lines, communication towers, and oil-waste pits. The U.S. Fish and Wildlife Service is currently mulling an update to address such issues.

Despite its antiquity, the act has helped hatch countless other movements that shield birds from modern threats. Here are some ways the protections of the MBTA are being expanded today:

Albatrosses and petrels are some of the world’s most endangered seabirds. Congress is currently deciding whether to ratify the Agreement on the Conservation of Albatrosses and Petrels, which would lead to the reduction of bird bycatch and the restoration of their habitat.

Each winter, Maine's Atlantic Puffins follow schools of fish to a rich cold-water reef system south of Cape Cod, Massachusetts. The National Audubon Society, along with several other conservation groups, scientists, and politicians, is urging President Obama to designate this underwater hotspot as the first Marine National Monument in the Atlantic. The effort would preserve the coral canyons for the many imperiled marine species that depend on them.

This June, the U.S. Fish and Wildlife Service announced that the Golden-cheeked Warbler would remain on the endangered species list, ensuring further protections for the songbird and its habitat. Almost 1.5 million acres of the warbler's breeding grounds have disappeared with rampant development in Texas Hill Country. The species also faces further future threats from climate change.

The Arctic National Wildlife Refuge contains 19 million acres of unspoiled forests and coastal plains—and yet the Obama Administration's plan to designate 12 million acres of the refuge as wilderness remains deadlocked in Congress. If passed, the proposal would help protect critical habitat for over 200 birds species that live in the region, including the American Golden Plover and the Spectacled Eider.

This February, Obama marked 1.8 million acres of California desert as a national monument, forging the second-largest arid preserve on Earth. From the San Bernadino National Forest, Joshua Tree National Park, and the Mojave National Preserve, the new monument covers habitat for 250 different bird species, including specialists such as the Elf Owl and the Least Bell’s Vireo.