BBC Radio 1 has lost nearly half a million listeners aged 30 and over, according to figures released by audience research body Rajar.
The latest Rajar figures show that the station pulled in an average weekly audience of 9.7 million listeners between January 5 and April 5.
This represents a fall on the numbers for the previous quarter, which stood at 10.4 million , while the yearly figure was 10.5 million.
The figures also showed that Nick Grimshaw's Radio 1 Breakfast show had 5.5 million weekly listeners, while the Chris Evans Breakfast Show on Radio 2 attracted 9.5 million listeners per week, down from 9.6 million last quarter and the record figure of 9.8 million last year.
Ben Cooper, controller of Radio 1 & 1Xtra, said: "Since Radio 1 has been completely focused on younger audiences - and the most common age of a Radio 1 listener is 21 - it was highly likely some older listeners would move on, like the half a million over-30s that left us this quarter. I'm pleased that Grimmy is doing what I've asked of him by keeping his young audience happy and scaring off the over-30s."
Meanwhile, Radio 4 Extra has peaked with its biggest audience yet, making it the largest digital-only station in the UK.
The sister station of Radio 4 saw an increase of a half a million listeners to increase their weekly reach to 2.2 million.
Helen Boaden, director of BBC Radio, said: "Radio 4 Extra was once a hidden gem in the BBC Radio portfolio.
"I'm delighted it has now been discovered by record numbers of listeners who are enjoying its unique blend of speech programmes, old and new. Our digital-only networks are coming of age and complementing our traditional stations in bringing distinctive content to a wide audience."
For Bauer Media, figures show that Magic Radio has shown year-on-year growth of 29%, with a reach of 3.6 million.
Richard Dunmall, group managing director of Bauer Advertising, said: "This set of Rajar results reinforces the success of our radio strategy. The fact that we have increased our share in commercial radio shows our ability to produce strong brands and engage with valuable audiences across the UK."