It has denied protection under the 1973 Endangered Species Act for three others, including the emperor and northern rockhopper penguins, stars of such popular movies as "March of the Penguins" and "Happy Feet."

The administration said there was not enough evidence to list the emperor as threatened because of global warming now or in the near future, although research has predicted that increasing temperatures could melt ice in Antarctica and also diminish populations of the penguin's preferred food such as krill.

About 390,000 emperor penguins live in 47 colonies in Antarctica. But while the populations of many penguin species are high, recent research has shown that about a dozen species are in decline because of numerous stresses, including climate change.

The other species not getting protection include the northern rockhopper penguin and the macaroni penguin.

"There are certainly issues with those species, but we did not believe at this time that the populations were reduced or that there were significant threats to lead us to make a determination that they are threatened with extinction," Kenneth Stansell, deputy director of the Fish and Wildlife Service, said in an interview.