The proportion of 13-17 year olds in the US who use Facebook fell to 88 per cent in 2014, down from 94 per cent last year.

Thats according to a Frank N. Magid report, which also found that Twitter usage among the same group rose to 44 per cent this year, up five percentage points on 2013.

Two of the factors driving this migration, it seems, is a lack of trust in Facebook itself – just nine per cent of respondents described the website as “safe” or “trustworthy”, far less than competing services – and dissatisfaction with its ad strategy.

33 per cent of Facebook users say there are too many ads, and 25 per cent identify the ads as disruptive and repetitive – roughly a third more than the number of Twitter users who say the same about that service.

This only looks set to worsen as Facebook increases its focus on video advertising. 20 per cent said they will spend less time on the social network as the result of these ads appearing in their feeds, a number that rises to 22 per cent among mobile users – and 25 per cent for 18-24 year olds.