Attracting the attention of such portals as the BBC, The Guardian and CNN, the project was born after one elephant started grieving following the death of one of the herd in March.

“Fredzia reacted strangely when she saw Erna’s body. She was really excited,” Dr Agnieszka Czujkowska, told the BBC, “but you could see that she was also grieving actually, she was also depressed.”

Having observed mounting signs of stress, zoo staff sensed the opportunity to trial a cannabis extract oil to see if it could help lighten the mood of the elephants in their care. Although medical cannabis has been successfully tested on such animals as dogs and horses, this is the first time that will it will be used on animals of this size.

“It’s an attempt to find a new natural alternative to the existing methods of combating stress, especially pharmaceutical drugs,” Czujkowska added.

Thought to stimulate serotonin and dopamine levels, the CBD oil will be administered via doses that will be taken through the trunk, and will not have any adverse effects on the animals. Neither, note zoo officials, will the elephants at any time be intoxicated.

Founded in 1928, Warsaw Zoo has long been associated with elephants. Kasia (pictured above), the institution’s first elephant, retains a near legendary reputation, as does Tuzinka. Born in 1937, at the time she became only the 12th elephant ever to be born into captivity and remains the only one born on Polish soil.