Planet Earth and Frozen Planet have deservedly bagged the BBC huge audiences in Britain with their ground-breaking wildlife footage.
Americans, however, haven't shown the same level of interest in the David Attenborough-narrated shows, according to one executive at US broadcaster Discovery.
Earlier this month, it was announced that a £150m co-production deal between the BBC and Discovery was to end "by mutual agreement".
The deal began in 1998 and resulted in shows such as Africa and Blue Planet. It was thought to bring in around £35m each year for the BBC.
Since then, however, the Discovery Channel has moved on to largely real-life broadcasting. Among its most popular shows are Deadliest Catch, which follows the lives of Alaskan fishermen, and Gold Rush, a constructed-reality show about miners.
According to Broadcast, Discovery executive Andrew Jackson, who is in charge of landmark series and specials, said BBC content was "under-performing" in the US. He claimed that American audiences preferred "real people doing real things".
He told the publication's Production and Post Forum: "What I discovered when I arrived was that the audience have moved on in America far greater than they have in the UK and anything that the BBC was doing - which is predicated on the licence fee, therefore they have to provide for the UK audience - was never going to catch up with where we had to take that kind of programming."
He claimed that in 2005, 16 of the top 40 Discovery shows came from the BBC. Last year, none originated from the BBC's prestigious Natural History Unit.
In contrast, episodes of Frozen Planet logged an average audience of 8.67m when they aired in 2011 in Britain.
Mr Jackson said he did not feel "at all guilty" about ending the deal, as in addition to the low ratings, Discovery had no rights to the BBC shows outside of the US.