U.S. wildlife authorities have added their voice to the chorus of ecologists and environmentalists who are fighting a proposed wind farm near the Pocosin Lakes National Wildlife Refuge in Eastern North Carolina.

The proposed 11,000-acre Pantego wind farm, with 49 turbines extending nearly 500 feet to the tip of the blade, would be located just several miles from a bird refuge that attracts swarms of migrating waterfowl during the winter months. The birds fly out at night to forage on nearby farms, some of which would host turbines with blades that can spin at over 100 miles per hour.

Critics worry the the blades will injure and kill flying birds, a phenomenon some have compared to a Cuisinart. The latest to express concern is the U.S. Fish & Wildlife Service in a filing made late Monday to the N.C. Utilities Commission, the agency that has the authority to approve, deny or delay the project.

The federal filing says the species at greatest risk is the tundra swan, a bird that can weigh up to 23 pounds, has a wingspan up to 5 1/2 feet, and flies at night to forage in nearby farms.