Federal wildlife officials have determined that a rare Alaska loon likely should be listed as threatened or endangered but that other species will take priority.

The U.S. Fish & Wildlife Service today said listing the yellow-billed loon under the Endangered Species Act is "warranted but precluded."

Yellow-billed loons breed in tundra wetlands of Alaska, Canada and Russia. They winter along the west coasts of Canada and the United States.

Conservation groups say the birds are some of the most vulnerable in the United States and are at risk from potential industrialization of the National Petroleum Reserve-Alaska west of Prudhoe Bay.