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The Trump administration has announced a position on protecting migratory birds that is a drastic pullback from policies in force for the past 100 years.

In 1916, amid the chaos of World War I, U.S. President Woodrow Wilson and King George V of Great Britain signed the . The wrote the treaty into U.S. law two years later. These measures protected by making it illegal to pursue, hunt, take, capture, kill or sell live or dead birds, feathers, eggs and nests, except as allowed by permit or regulated hunting.

This bold move was prompted by the decimation of bird populations across North America. Some 5 million birds, especially waterbirds like egrets and herons, were dying yearly to provide , and the passenger pigeon . Fearing that other species would meet the same fate, national leaders took action.

Now the Interior Department has issued a that reinterprets the act and excludes "incidental take" – activities that are not intended to harm birds, but do so directly in ways that could have been foreseen, such as filling in wetlands where migrating birds rest and feed. Why? For fear of "unlimited potential for criminal prosecution." As the argument goes, cat owners whose pets attack migratory birds or drivers who accidentally strike birds with their cars might be charged with crimes.

But the MBTA has not been enforced this way. It is applied to cases of gross negligence where potential harm should have been anticipated and avoided, such as into a pond used by migratory birds. This new reading of the law means that companies will escape legal responsibility and liability for actions that kill millions of birds every year.

Pollution, development and habitat loss kill birds

Purposeful killing is only one of many threats to migratory birds. Habitat loss, invasive species, pollution and collisions with buildings take heavy tolls on many species. According to the U.S. Fish and Wildlife Service, every year by industrial activities or structures such as power lines, oil pits, communication towers and wind turbines. The 2010 in the Gulf of Mexico killed more than 1 million birds in a single event.

Seventeen former Interior Department officials representing every presidential administration from Nixon through Obama have written a expressing deep concern about the new policy. As they explain, the MBTA has given industries a strong and effective incentive to work with government agencies to anticipate, avoid and mitigate foreseeable death or injury to birds.

For example, it prompted energy companies to install nets above pits where they store waste fluids from oil drilling. Because these pits look like water sources, birds often land on them and can become trapped and die. Installing nets over the pits has from roughly two million birds yearly to between 500,000 and one million. Not perfect, but a meaningful improvement.

Global citizens, global consequences

Because migratory birds don't recognize international boundaries, the consequences of reinterpreting the MBTA may be felt across borders. In one year, an individual warbler may spend 80 days in Canada's boreal forests, 30 days in the United States at resting and refueling sites during migration, and over 200 days in Central America.

At the , we have constructed maps and using data collected by volunteers for , the world's fastest-growing biodiversity database. These references illustrate how migratory birds connect countries. Many spend the year in locations that span the Western Hemisphere.

The eastern-breeding , for example, spends winters in areas in the Yucatan Peninsula and Central America that are fractions of the size of its breeding range. Seeing how densely these birds are clustered in their winter habitat shows us that each acre of that territory is important to their survival.

Similarly, most populations of the western-breeding overwinter in Mexico. By identifying where bird populations winter in this way, we can better target conservation actions to protect species throughout their annual cycles.

Still at risk

Today we know much more than early conservationists did about the value of birds. Healthy bird populations and help plants grow by and . Migratory birds also contribute billions of dollars to economies through . And they connect us with nature, especially through the dazzling spectacle of migration.

Conserving migratory birds requires effective protection both in the United States and through international agreements and partnerships. The most important threats are loss and degradation of habitat, which can be caused by land conversion – for example, clearing forests for farming – or by climate change.

In the 2016 report, an international team of scientists assessed the conservation status of 1,154 birds across Canada, the United States and Mexico. They found that over one-third of all North American bird species are at risk of extinction without meaningful conservation action.

Birds associated with oceans and tropical and subtropical forests year-round are in the most dire straits. More than half of North American seabirds are declining due to pollution, unsustainable fishing, energy extraction, pressure from invasive species and climate change. Birds that rely on coasts, arid lands and grasslands also are in serious decline.

There are no easy solutions, but new science is supporting responses. Transformational citizen science projects like are developing vast data sets to help pinpoint where conservation action should focus. Bird conservation groups and government agencies have formed international teams to that are critical to breeding seabirds and drafted multinational agreements to in our seas that can choke, trap or poison seabirds and other animals.

Birds are a shared resource among nations. Where governments have acted, they have successfully protected migratory birds and the habitat they depend on. In my view, the Trump administration's shift would abdicate U.S. leadership on migratory bird conservation and undermine public good for private profit.

This article was originally published on . Read the .