An Oregon Congressman is calling for federal intervention to protect gray wolves that range beyond Yellowstone National Park, saying that without it the health of the park’s wolf population will suffer.

In a letter to Interior Secretary of the Interior Sally Jewell, Rep. Peter DeFazio (D-Oregon) argues that hunters killing wolves just outside Yellowstone’s boundary is contributing to the recent decline in Yellowstone’s wolf population.

“For over three years, the population of gray wolves in Yellowstone has steadily decreased as a result of hunting-related deaths. According to wildlife biologists, Yellowstone’s wolf population dropped 25% between 2011 and 2012. The National Park Service reports that as of March 1, 2013, 12 Yellowstone National Park wolves were legally harvested just outside the park borders,” DeFazio wrote.

Wolf packs once roamed from the Arctic tundra down to Mexico, but loss of habitat and a series of extermination programs devastated the species. By the early 1900s, wolf populations were scant, and by 1973, the gray wolf was listed as an endangered species.

At this point, the U.S. Fish and Wildlife Service designated Yellowstone National Park as one of three key recovery areas. From 1995 to 1997, 41 wild wolves from Canada and northwest Montana were released in Yellowstone. And as predicted, the wolves from the growing population dispersed to establish territories outside the park.

In 2011, Congress legislated a U.S. Fish and Wildlife Service proposal to prematurely delist the gray wolf in Idaho, Montana, parts of Oregon and Washington. Since then a number of wolves have been killed just outside park borders.

DeFazio is asking the Department of Interior to establish a “wolf safety zone” or buffer zone around Yellowstone, which would include parts of Montana, Wyoming and Idaho. He also asked Jewell to establish an “Interagency Wolf Task Force for the purpose of coordinating across the federal and state agencies to protect park wolves from adverse effects of trophy hunting and other causes of human-induced mortality in all National Parks with wolf populations.”

The Rocky Mountain Elk Foundation (RMEF) has responded to the Congressmen with a letter of their own, writing that the request for a buffer zone is “unfounded by any science and contradicts what the entire wolf reintroduction and ESA listing represent.”

Since the gray wolf has been reintroduced in the Northern Rocky Mountains, the population has not only met its recovery goal, but surpassed that benchmark by 500%. The RMEF also makes note that “states are the appropriate authority to manage their wildlife,” mostly by implementing strict management quotas.

The organization also goes on to point to a number of scientific reasons that account for the decline in wolf numbers in Yellowstone Park. Most notably, they say, is the availability of elk — the primary prey of northern range wolves — which has declined significantly. Yellowstone’s northern elk herd has fallen from 17,000 animals in 1995 to roughly 4,000 in 2013. The organization also point to another recent study which demonstrated that wolves will kill one another when an area’s population becomes too large for the available prey and habitat.

Whether a buffer zone surrounding Yellowstone Park is necessary is still up for debate. It is certain, however, that wolves have a very important and very powerful effect on the well-being of the ecosystem.

When the gray wolf was removed from Yellowstone in the 1920s, the park’s entire ecosystem changed.

“The wolves were killed off from Yellowstone in the 1920s, which correlated with the start of the aspen decline. That led us to develop the hypothesis that the wolves were connected some way to the aspen trees,” says ecologists William Ripple and Robert Beschta of Oregon State University. The connection, they believe, was made through elk. “We connected the dots: wolves affect elk; elk affect aspen; and therefore wolves affect aspen.”

Since the wolves have been reintroduced, “the recovery of that system to its natural balance is well underway,” says Ripple. Stands of aspen and other native vegetation, once destroyed by overgrazing, are now growing up along the banks. Now, the greenery can grow tall enough to reproduce.

The ripple effect extends well beyond the trees. Beavers, for example, also benefit from the presence of wolves. The healthy vegetation provides food and shelter, allowing the beavers to create dams that help keep waterways clean and lessen the impact of the drought. Beaver activity also helps to provide ideal habitat for a number of amphibians, fish, birds and small mammals. The healthy vegetation also keeps the rivers from flooding, which allows for richer soil that better sequesters carbon.