After a week of spring-like weather that raised temperatures and hopes in the wintry soul of Washington, officials at the National Zoo report warm winds of tranquility wafting from the Panda House, where spring in the past has seen a lot of bad karma.

Giant pandas Ling-Ling and Hsing-Hsing, for whom mating season can be tense, got some new furniture last summer and, like many couples who've had their place redone, seem to have found in it an improved relationship.

"They've been spending much more time with each other, playing all over the furniture," said Devra Kleiman, the zoo's director of animal programs and designated panda yenta. "There's much less aggressive behavior. It's almost vanished."

In addition, she said, Ling-Ling, the female who used to carp at and intimidate her not-exactly-swaggering mate and loudly rebuff his tentative efforts at sociability, has suddenly turned coy.

"She's flirting!" said Kleiman, rather enchanted at the prospect. "She waits for him and then pats him and runs away. It's very provocative behavior."

This only happens about 45 minutes a day -- from 7:30 a.m., when the pandas are let outside for the day, to about 8:15 a.m. But even so, Kleiman said, it's unprecedented in the 13 years of highly documented behavior since the pandas were given to the zoo by the people of China.

"We never expected anything like this," she said. "It shows the benefits of providing animals the challenge of a more complex environment." The flirting also bodes well, she said, for the pandas' once-a-year mating season, which usually occurs in mid-March.

The unending melodrama of the panda's reproductive efforts over the years has become something of an obsession in Washington. When they finally mated successfully in 1983 after 11 unsuccessful years, films of the event were shown on local television.

Ling-Ling has given birth twice since, but both cubs died of infection, one before birth and one shortly afterward.

While the once-hapless Hsing-Hsing has become somewhat more assertive since the two matings, Kleiman said the real factor in the pandas' changed behavor appears to be the new furniture, a jungle-gym complex of wooden platforms, balance beams, swings and stairs assembled by volunteers last summer.

Designed primarily for exercise, it also permits the animals to be near each other without competing for the same raised platform. The pandas were slow to use it at first but have taken to it increasingly in the active first hour of their outdoor day, and since January have shown a repetitive pattern of king-of-the-mountain play, much of it initiated by the once-hostile Ling-Ling.

One morning early this week, when the gate between the two yards was opened, the animals repaired to Ling-Ling's furniture complex for a cuffing duel on a swinging bridge about five feet off the ground.

Kleiman says that while she's not ready, after 13 years of near misses, to say this is the year for a healthy baby panda, it well may be.

"I'm always optimistic," she says. "But this year we may have the best chance we'll ever have."

The one question is Ling-Ling's health, as she seems to be prone to low-grade infections. "But she appears to be extremely vigorous and healthy," Kleiman says.

Kleiman, who has her hands full annually with people projecting their own relationship problems onto the pandas, sticks to the science of pandadom, resisting the narcotic lure of anthropromorphic comedy.

But she confesses there's one more beguiling sign in this year's panda Spring: once tremulous Hsing-Hsing is swaggering around at 300 pounds, eating everything in sight. Newly amiable Ling-Ling is svelte at 240 pounds and picking at bamboo salads.