Is â€˜lonelyâ€™ polar bear going crazy?

Baking heat ... Experts fear the solitude and the soaring temperatures are getting to Arturo. Picture: Youtube Source: Supplied

ANIMAL campaigners are seriously worried about the mental health of a polar bear in an Argentine zoo, saying he is lonely, depressed and showing signs of going insane.

Arturo is the last polar bear in Argentina and has been on his own his pen at the Mendoza Zoo since his companion died two years ago.

Experts fear the solitude and the soaring temperatures (it can reach up to 40C in the summer months) are getting to him, the Independent reported.

They say his behaviour has become "abnormal" with the animal filmed pacing back and forth, swaying his head from side to side and bearing his teeth.

Lonely ... Arturo is the last polar bear in Argentina. Picture: Youtube Source: Supplied

An online petition on Change.org calling for Arturo to be moved to a zoo in Canada where the temperatures are more in line with his natural habitat has attracted 25,000 signatures.

But despite pressure from protesters experts say the 25-year-old bear is too old and fragile to make the journey north.

Campaigners, however, dismissed this evaluation and said the bear needed to be moved to avoid a similar fate to Winner, a polar bear from Argentina's Buenos Aires City Zoo, who was killed by the high temperatures in a heatwave that hit the city in 2012.