MINNEAPOLIS — A federal plan to let hunters shoot trumpeter swans has drawn fire from some of the people who toiled to bring the majestic white birds back from the brink of extinction.

Trumpeter swans, North America’s largest waterfowl species, have made a comeback in recent decades thanks to efforts to reintroduce them to their former breeding range.

Now the U.S. Fish and Wildlife Service is working on a plan that would let hunters shoot them in several states that allow the hunting of tundra swans, a more numerous species.

“Trumpeter swans are a conservation success story,” said Brad Bortner, chief of the service’s migratory bird management division. North America’s population is estimated at more than 63,000 adult birds and it’s growing by more than 10,000 a year, he said.

No state is currently proposing trumpeter swan seasons, he said, and the proposal is mostly aimed at protecting tundra swan hunters in five states who may mistakenly kill trumpeter swans.

But he acknowledged the proposal opens the door to the possibility that some states could offer such a hunting season. The soonest the proposal could take effect is the 2019-2020 season.

Tundra swans look almost identical to trumpeter swans, especially at a distance, and a tundra swan hunter who mistakenly shoots a trumpeter is subject to a fine. That rarely happens.

But the risk is expected to grow as trumpeter swans spread from states that have invested heavily in restoration efforts, such as Minnesota, Iowa, Wisconsin and Michigan in the Mississippi Flyway.

The proposal essentially would make such incidental kills legal by letting states with low trumpeter numbers hold general swan seasons rather than specific tundra swan seasons.

The service already allows something similar in the Pacific Flyway in Utah and Nevada. The new plan would most directly protect tundra swan hunters in Montana, North Dakota, South Dakota, North Carolina and Virginia.

The Fish and Wildlife Service put the plan out for public comments this summer. The online comment period closes Sunday.