NEW YORK: Two thirds of the most-watched cable TV channels in the US experienced significant ratings declines during July, with a variety of reasons being put forward, from changing consumer behaviour to more aggressive network programming.

Nielsen data revealed double-digit declines, compared to the same month in 2014, at TNT (-22%), Disney Channel (-19%), Bravo (-23%) and MTV (-24%), among others. In all, prime-time ratings dropped at 21 of the top 30 cable channels, the Wall Street Journal reported.

One explanation may be that Nielsen data has yet to take account of changing consumer viewing patterns as it does not include content being watched on tablets and mobile phones.

Another factor is that "People are getting used to using summer to binge view and catch-up", according to Billie Gold, vp/director of programming at media agency Dentsu.

This typically involves viewers devoting more time to VOD or stored DVR shows and less to the new shows that cable networks have launched at this time of year when the broadcast networks' traditional fall-spring season has ended.

But the broadcast networks have now flooded their summer schedules with both reality and scripted shows, while the continued growth of streaming services such as Netflix and Hulu has also hit cable audiences.

"The bar has been raised," said David Bank, an analyst at RBC Capital Markets, who pointed out that a summer break was no longer possible for the networks.

"You run the risk of losing more audience", he warned, if you take time out while other channels continue to produce fresh content.

Research firm SNL Kagan recently reported that pay-TV operators had lost 625,000 video subscribers in the second quarter of 2015, the largest quarterly drop on record and warned the trend was likely to continue for the rest of the year.

Data sourced from Wall Street Journal; additional content by Warc staff