The BBC's black music radio station 1Xtra has been the most successful of the BBC's four new digital stations, listening figures have revealed.
1Xtra was one of four digital-only BBC stations launched in 2002
1Xtra, which broadcasts hip-hop, R&B and garage, averaged 313,000 listeners per week during the last three months, official Rajar ratings showed.
BBC Radio 2 is still the UK's most popular station but its audience slipped 500,000 to 12.5 million.
In London, long-term number one station Capital has been overtaken by Heart.
The Rajar figures, which cover three months from July to September, are the first to track the audiences of the BBC's digital stations.
BBC DIGITAL-ONLY RADIO STATIONS, WEEKLY AUDIENCE
1Xtra - 331,000
Five Live Sports Extra - 312,000
BBC7 - 236,000
6Music - 154,000
The BBC launched 1Xtra, BBC7, Five Live Sports Extra, and 6Music last year - to complement digital broadcasts of its existing stations.
The ratings put 1Xtra ahead of Five Live Sports Extra, which broadcasts sports commentaries and had 312,000 listeners per week.
BBC7, which includes children's shows plus spoken word comedy and drama, had an audience of 236,000.
And 6Music, specialising in classic rock and alternative music, had 154,000 per week, the figures showed.
But 6Music's audience was the most dedicated, the BBC said, tuning in for about five hours a week each - longer than listeners to its three sister stations.
BBC MAINSTREAM RADIO, WEEKLY AUDIENCE
Radio 1 - 9.9 million
Radio 2 - 12.5million
Radio 3 - 2.2million
Radio 4 - 9.5m
Five Live - 5.7m
BBC director of Radio and Music, Jenny Abramsky, said they were "very encouraging figures".
"The age of digital radio has come at last and the BBC has played a crucial role in getting us there," she said.
Earlier this week, she warned that the first digital figures would be "modest", but stressed that "these are very early days".
The BBC's digital stations are still behind other digital broadcasters, especially those based on magazines such as Smash Hits, Kerrang! and Q.
In mainstream listening, Radio 2 slipped further from the record high of 13.3 million it recorded at the start of this year, while Radio 1 and Radio 4 also dropped slightly.
Capital's flagship 95.8 FM London station, which had been the top commercial broadcaster in the city for 30 years, saw its share of the market drop from 8.9% to 7% in the last three months.
Heart 106.2 rose from 6.7% to 7.2% in the same period.