On a remote island in the Indian Ocean, researchers have spotted fur seals sexually harassing and coercing king penguins.

On at least four occasions, the large mammals have been recorded forcing the birds to the ground and attempting to mate with them.

After three of the incidents, the seals let the penguins go - but following one attack, the seal killed the penguin and ate it.

This article contains images and video that some readers may find disturbing

On four recent occasions, researchers spotted Antarctic fur seals sexually harassing king penguins (pictured). In three of the four incidents, the seal let the penguin go, but following one occurrence, the seal killed and ate the penguin

Scientists from the University of Pretoria regularly monitor wildlife on Marion Island for rare and unusual behaviour.

Although the behaviour has been spotted once before, in 2006, this recent spate suggests the acts are becoming more widespread.

FUR SEALS MATING WITH PENGUINS Each of the four recorded sexual incidents showed the seal chasing, capturing and mounting the penguins. They then attempted to copulate for between two-and-a-half minutes and six minutes, before they are seen resting and trying again. The average copulation time was five minutes. Experts suggest it may have become a learned behaviour, because the incidents have occurred with different fur seals. And the incidents may continue, but the reasons why the seals have started to exhibit this behaviour are not known. The researchers speculated that the seals may be sexually inexperienced, or frustrated, or it may be an act of aggression. They may also have difficulty recognising female seal partners. Advertisement

‘Honestly I did not expect that follow up sightings of a similar nature to that 2006 one would ever be made again, and certainly not on multiple occasions,’ Nico de Bruyn, of the Mammal Research Institute at the University of Pretoria, South Africa told the BBC.

Each of the four recorded sexual incidents showed the seal chasing, capturing and mounting the penguins.

They then attempted to copulate for between two-and-a-half minutes and six minutes at a time, before they are seen resting and trying again.

The average copulation time was five minutes.

The seals were all male, but the gender of the penguins isn’t known.

Experts suggest it may have become a learned behaviour, because the incidents have occurred with different fur seals.

And the incidents may continue - but the reasons why the seals have started to exhibit this behaviour are not known.

'Determining the drivers of the unusual behaviour is nearly impossible,' explained the researchers.

'However, we speculate as to what may have ultimately led to the sexual coercion of individuals from these very different species.'

For example, Mr De Bruyn originally suggested the sexual coercion was a result of the seal's predatory behaviour towards the penguins being redirected into sexual arousal.

Experts suggest it may have become a learned behaviour, but, the reasons why the seals have started to exhibit it are not known. During a number of the attacks, the experts said the seals successfully penetrated the birds, and during the most recent, in December 2012, blood was seen between the bird’s legs (bottom left)

But, in light of the 2011 attack - when the seal killed the penguin - he added that this seems less plausible.

He therefore believes the behaviour may have been learned

The researchers have speculated that the seals may also be sexually inexperienced, or frustrated, or it may be an act of aggression.

They may also have difficulty recognising female seal partners.

Scientists from the University of Pretoria monitor wildlife on sub-Antarctic Marion Island (marked) for rare and unusual behaviour. In 2006, the incident was spotted on Trypot beach. The most recent occurrences took place on Goodhope Bay and Funk beach

During a number of the attacks, the researchers said the seals successfully penetrated the birds, and during the most recent - in December 2012 - blood was seen between the bird’s legs.

In 2006, the incident was spotted on Trypot beach. The most recent occurrences took place on Goodhope Bay and Funk beach.