A male swan named Gvidon on display at a Russian zoo passed away a month after losing his longtime companion in a shocking act of animal cruelty - and keepers say a broken heart is to blame.

The swan's bonded mate, Tsarevna, was killed in January when a guest at the Limpopo Zoo fed her bread that had a sewing needle hidden inside it. Shortly after the deadly attack, Gvidon began exhibiting signs of depression, refusing to eat normally and shying away from the remainder of the flock, zoo officials said in a statement.

Keepers said they tried to console the heartbroken bird, but as the weeks carried on, lonely Gvidon's sadness only seemed to deepen.

"Like humans, [animals] can suffer from depression," said the zoo's deputy director.

As Gvidon's condition deteriorated, he was moved into the zoo's veterinary hospital, where he began to refuse food entirely. Within days, he was dead. Officials said the cause of death was clear, telling the Moscow Times:

"Gvidon literally didn't want to live without his beloved Tsarevna."