Radio 1 breakfast DJ Nick Grimshaw lost just over 300,000 listeners in the third quarter, and is now more than one million below the audience level enjoyed by his predecessor Chris Moyles.
Grimshaw's breakfast show attracted 5.58 million listeners on average each week in the three months to 24 October, according to the latest official Rajar figures published on Thursday.
This was down 305,000 on the previous quarter's 5.88m, when Grimshaw managed to stem the exodus, posting a slight increase in listeners, and 17% on the same quarter in 2012.
The 29-year-old's audience is now 1.12 million below that of Moyles' last quarterly listener figure of 6.7 million.
Grimshaw is on the brink of breaking Sara Cox's 2003 audience low of 5.5 million listeners, recorded in her last three months in the job before she was replaced by Moyles.
Radio 1 had an average weekly audience of 10.8 million, a 1.8% quarter-on-quarter fall, during the three-month period.
The BBC defended the 1.1 million decline in Grimshaw's weekly listeners in a year, pointing out that 72% of those switching off are 30 years old or more.
Radio 1 and 1Xtra controller Ben Cooper appointed Grimshaw to replace Moyles as part of his strategy to make the station more appealing to younger listeners. The BBC Trust told executives in 2009 to refocus Radio 1 around its target demographic of 15- to 29-year-olds – Moyles' audience included about 1 million 45 to 54-year olds.
"After the biggest set of changes to Radio 1 for a generation, we're really happy that the Breakfast Show sounds fresher, younger and more vibrant than ever," said Cooper. "As a result 833,000 of the show's '30 and over' listeners have moved on to other stations."
Radio 2 breakfast presenter Chris Evans also lost listeners, down 405,000 quarter on quarter, although he remains the UK's most popular breakfast DJ.
Evans' show attracted 9.34 million weekly listeners on average in the third quarter, up 800,000 on the same period last year.
Overall, Radio 2 lost 3.3% of its listeners quarter on quarter, down to 14.9 million.
The Radio 1 breakfast show once again trailed behind Radio 4's Today programme, which slightly dipped quarter on quarter to 6.8 million listeners.
Radio 4's total audience fell by 1% quarter on quarter to 10.86 million.
Radio 3 saw another drop in its breakfast audience, from 615,000 to 533,000. But the station's total listener numbers rose 1.5% quarter on quarter to just over 2 million, during a period that included its annual coverage of the Proms.
BBC 6 Music attracted 1.73 million listeners on average in the quarter, down 3.4% over the previous three months, but up 6.9% year on year.
BBC Radio 5 Live grew its audience by 1.4% in the quarter to 6.12 million, rising 0.5% year on year. Digital sister station Radio 5 Live Sports Extra, which carried live Test Match Special coverage of England's Ashes cricket victory over Australia, attracted a record 1.52 million listeners, up 60.7% quarter on quarter and 51.4% year on year.
BBC's Asian Network fell 5.5% quarter on quarter and 5% year on year to 555,000 listeners on average each week.
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