A university academic has criticised David Attenborough's wildlife shows for not featuring enough gay animals.
Three of the veteran broadcaster's shows are identified in a new study as perpetuating the notion that animal relationships are predominantly heterosexual.
Dr Brett Mills of the University of East Anglia says wildlife documentaries should be offering viewers a wider perspective on animal behaviour.
Researchers found BBC wildlife documentaries portray animals as heterosexual families too often, even though animals can also be gay.
Dr Mills who carried out the study said: 'The central role in documentary stories of pairing, mating and raising offspring commonly rests on assumptions of heterosexuality within the animal kingdom.'
Dr Mills says this perception is created by the documentaries despite evidence that show animals have 'complex and changeable forms of sexual activity, with heterosexuality only one of many possible options.'
The study focussed on three BBC wildlife documentaries The Life of Birds, The Life of Mammals and Life in the Freezer, and analysed the way in which the animals were described in voiceovers.
"Voiceovers tell the audience how to make sense of what is being seen. The environment, via the voiceover, is interpreted and understood via decidedly human cultural norms and assumptions", Dr Mills said.
The study was published today in the European Journal of Cultural Studies.