"It was horrible," experienced parrot breeder Torny Sjökvist, who hails from the village of Skara in central Sweden, told the Aftonbladet newspaper.
Sjökvist made the grisly discovery on Sunday morning when he walked out into a suspiciously quiet backyard where the cages housing his valuable birds are kept.
At first, he noticed one dead parrot lying on the floor of its cage.
But upon closer inspection, Sjökvist's initial sadness turned to utter shock when he discovered that some twenty of his beloved parrots were dead in their cages
Several appeared to have been beaten, while others had apparently been bitten by some other animal.
"I'd had some of them for ten, fifteen years," he told the newspaper.
"I'd raised them myself."
Among the bevy of slain birds were a Rose-breasted Cockatoos, Amazon parrots, and Golden Parakeets, which are exceedingly rare.
"There's only one other pair of them in Sweden, and I had a special permit in order to have them. The goal was to breed more," said Sjöqvist.
In addition to the emotional toll caused by the mass killing, Sjöqvist's parrot breeding business stands to take a massive financial blow following the massacre.
"The Golden Parakeets alone were worth 150,000 kronor ($17,000)," he told Aftonbladet.
As one of the birds was found dead outside its closed cage, Sjöqvist suspects a human was involved in the attack, dismissing theories that a ferret could have been the culprit.
"No ferret can get through my nets – they're too tight. I've had parrots like this for 25 years," he said.
"I think someone let in a mink and beat some of them to death."
Police have launched an investigation into the matter, which is believed to have taken place between 9pm on Saturday night and noon on Sunday.