Traditionally, U.S. indie drama plays better at home than abroad. So the fact that the international gross for both “Black Swan” and “Winter’s Bone” has outpaced domestic is a rare event, which offers fresh hope to American producers seeking foreign buyers for challenging fare.

With the contraction of the Stateside specialty sector, U.S. indie producers need the international market more than ever in to get their movies made.

And American indies have become sparse in the high-profile platform that Cannes competition offers; discounting the established helmers, there are precious few indie newcomers on the list.

But the kind of films that win prizes at Sundance rarely travel well. Even such crossover hits as “Little Miss Sunshine” and “Juno” earned twice as much in North America as elsewhere. The foreign performance of “Black Swan” and “Winter’s Bone” is virtually unprecedented.

The question is whether that’s just a coincidence, or a genuine breakthrough for American indie cinema?

“Black Swan,” which was offered to foreign distribs before Fox Searchlight took it off the table, has earned $162 million overseas, dwarfing its $102 million domestic take.

Yet in some ways, more surprising is the fact that $2 million backwoods drama “Winter’s Bone,” the archetypal dark Sundance prize-winner, has reached $7.7 million abroad, passing its American gross of $6.5 million.

“It will be interesting to see if this is a watershed moment that tips the balance for us in the international market,” says producer Ted Hope. ” ‘Black Swan’ is one of the top directors working in a popular genre with a star cast, but ‘Winter’s Bone’ is a true Sundance film if there ever was one, with an unknown in the lead. It has a genre element, to be sure, but it’s still a drama in a non-glamorous setting.”

Yet “Winter’s Bone” also has marketable thriller elements and an attractive teenage heroine to go with the five-star reviews that made it a must-see for the arthouse crowd in many territories.

” ‘Winter’s Bone’ is truly the gift that keeps on giving. It’s into overages everywhere,” says Nicole Mackey of sales agent Fortissimo, which picked up the pic at Sundance 2010.

It was the Oscar heat for “Winter’s Bone,” not its Sundance prize, which fanned the foreign flames. “Some territories didn’t sell until right at the end of last year, when it was really winning awards,” Mackey says. “It still hasn’t sold in China, India and Indonesia, but that’s about it. And it has done extraordinary business in places like Sweden.”

In fact, Sweden is the pic’s second-biggest territory after North America. Local distrib NonStop has racked up $2.6 million across Scandinavia.

“If you look at Scandinavia and Sweden in general, audiences tend not to shy away from movies with dark topics,” says NonStop topper Ignas Scheynius. “Dark-themed movies with a strong female protagonist do well for us, like ‘Fish Tank’ and ‘Frozen River.’?”

Ralph Dietrich of German/Swiss distrib Ascot Elite, says “Winter’s Bone” defies conventional wisdom.

“We did have movies before that won in Sundance but didn’t break out. ‘Winter’s Bone’ is a very American movie, and Germany is a very tough market for these films. ”

Dietrich says the film’s Oscar nominations triggered a surge in German media interest, prompting him to double the scale of his release. But he notes the difficulty and expense of dubbing such vernacular American filmmaking, which is one reason why U.S. indie pics with a distinctive voice often don’t travel well. “There’s a lot between the lines. It’s easier to dub a big action movie.”

One Sundance 2011 pic, cult thriller “Martha Marcy May Marlene,” has elements to make an overseas play; its slot in Un Certain Regard guarantees a international profile.

Danny Perkins, CEO of the U.K.’s Optimum Releasing, puts the results for “Black Swan” and “Winter’s Bone” into the wider context of this year’s Oscar season, when a slew of American specialty dramas delivered surprising, and in some cases exceptional, box office results.

“If you look at ‘Black Swan,’ ‘True Grit,’ ‘127 Hours,’ ‘The Fighter’ — the encouraging thing is that audiences want to go and see something original, something that’s a bit left of center, and that hasn’t been the case for a while,” he says.

Of course, not all this year’s indie crop have been embraced with equal enthusiasm. “The Fighter” has only punched its weight in English-speaking territories, earning $30 million in foreign, far short of its $95 million domestic total. “The Kids Are All Right” tallied an acceptable $12.6 million foreign v. $20 million domestic. Another Focus pic, Sofia Coppola’s “Somewhere,” took $12.6 million abroad, mostly in France, Italy and Germany, against just $1.8 million in the States.

Marital break-up drama “Blue Valentine” sold strongly and performed well in Australia, according to Hyde Park Intl.’s Mimi Steinbauer, though results elsewhere have been patchy. The big flop, however, was “Rabbit Hole,” described as “abysmal” by one source close to its sales, taking just $1.4 million in foreign so far against $2.2 million domestic.

Those kinds of figures give U.S. indie drama a bad name among buyers and sellers. As Sam Horley of London sales agency Salt says, “Our mantra is, we don’t do bleak. We turned down ‘Winter’s Bone.’ For every one of those films that does really well, there are 20 that don’t.”

Horley learned her lesson with “White Lightnin’,” another Sundance entry set in gritty rural America. “It had a huge amount of critical acclaim, but it was a disaster for us financially.”

But Salt is now handling Abe Sylvia’s debut “Dirty Girl,” a campy high school dramedy, aimed at the “Little Miss Sunshine” crowd. “A couple of territories are going to need convincing that it’s not too American, but what attracted us is that the director influences are the Australian films of the ’90s — ‘Priscilla,’ ‘Muriel’s Wedding,’ ‘Strictly Ballroom,’ ” Horley says.

The top American indie producers such as Hope and Christine Vachon are more aware than ever of the need to appeal to international tastes. They are adding a twist of genre to their slates in response to foreign demands, cutting budgets and beefing up casts.

Vachon has teamed with U.K. sales agent Bankside for vampire movie “Innocence,” starring Julianne Moore. Hope has just delivered skewed superhero comedy “Super”; and the Todd Solondz pic “Dark Horse,” which pre-sold to Scandinavia and Australia. Now he’s putting together Chris Monger’s “Amateur Photographer” with Daniel Radcliffe.

“All of the foreign sales agents were constantly asking for more genre projects,” Hope says. As for casting, he reports that foreign buyers have become more sophisticated. “They used to want someone who was hot two years ago, now they prefer the ‘Chinese menu’ approach, where you have one traditional name, one breakout name and somebody who’s significant in terms of TV acquisition — that smorgasbord gives people hope of capturing magic in a bottle.”

With the Internet speeding up the starmaking process, foreign distribs are more alert to coming names, such as Mila Kunis and Deborah Lawrence.

Foreign actors also help, like Vincent Cassel in “Black Swan.” Focus is reporting strong sales for “Beginners,” a comedy from Mike Mills, starring two Brits, Ewan McGregor and Christopher Plummer, and France’s Melanie Laurent. “The combination of that acting talent helped to broaden the appeal to the international market,” says Focus Intl. topper Alison Thompson. “Films that are about American navel-gazing, I don’t think international audience find them very interesting.”

It’s no accident that Focus has weighted its slate toward international productions such as “Jane Eyre” and “One Day” — a Lone Scherfig film that stars Anne Hathaway and Jim Sturgess — in recent years. But perhaps in response to the shake-out of domestic distribution, Thompson now sees signs that U.S. filmmakers are raising their game, which will be reflected in stronger product for sale at Cannes.

“I finally think there’s interesting stuff coming through from America, after quite a barren time in terms of American auteurs,” she says.

Cannes Preview:
American indies welcome abroad | Cannes market sees 10% rise | Cannes market watch | Visual effects help sell dinorsaur pic