PORTLAND — After two decades on the nation’s list of threatened plants and animals, the northern spotted owl is losing ground faster than previously thought, federal agency managers said Thursday.

The owl has long been in jeopardy because of the loss of the Pacific Northwest habitat it prefe

rs, old-growth forests.

Now, though, the federal officials in charge of saving it from extinction say the spotted owl’s numbers are dropping at a rate of 3 percent a year, under pressure from a larger, more aggressive rival from the eastern United States, the barred owl.

“This is the pressing short-term threat to the spotted owl,” said Robyn Thorson, northwest regional director of the U.S. Fish and Wildlife Service.

Thorson and other federal agency managers unveiled a new recovery plan Thursday for the spotted owl. It is latest in a long string of attempts to find a lasting balance between saving the bird from extinction and allowing logging on Northwest national forests — something neither the Clinton nor Bush administrations could do.

The recovery plan doesn’t specify how the barred owl’s invasion might be blunted. Federal officials have talked about shooting some of them to allow the spotted owl to move back into its habitat, but officials said Thursday there are alternatives.

An environmental assessment due later this year is expected to lay out the possibilities. Federal officials also are expected this fall to begin designating critical habitat for the spotted owls, a key part of the way the Endangered Species Act works.

The barred owl is not in jeopardy and is instead expanding its range into California.

The new plan includes a computer model designed to help biologists evaluate the effects of logging and forest thinning on spotted owl habitat, so protection for the bird can evolve over time and in the face of changing conditions, such as climate change and wildfires.

The new plan comes after pitched legal and political battles in which the spotted owl has been a symbol of conflicts between jobs and environmental protection in a region where high-paying jobs in logging and timber mills were once widespread but have been squeezed out by automation, corporate consolidation and changes in federal land management.

Environmental groups were largely satisfied with the Northwest Forest Plan put in place in 1994 by the Clinton administration, which cut logging by 90 percent in Washington, Oregon and Northern California to protect owl habitat and lifted injunctions on logging federal timberlands.

The timber industry supported Bush administration efforts to dismantle the Northwest Forest plan and create a new owl recovery plan, but both were struck down by federal courts.

That left the Obama administration to create its owl recovery plan. Both conservation groups and the timber industry have been critical of the plan as it has developed.