The gruesome discovery was made by someone assigned by the pigeons’ owner to feed the birds.
“Someone broke in there and broke the necks of all the doves,” said Jeanette Lövqvist of the Mölndal police to the TT news agency.
The cage belongs to a carrier pigeon club and the last time the birds were seen alive was when there were last fed on Friday around lunchtime.
The incident was reported to police on Sunday morning, but police have no theories about who could have killed the pigeons.
The crime has been classified as vandalism.
According to the Göteborgs-Posten newspaper, a similar incident took place in the Lärjeholms allotment area on Christmas Eve three years ago when someone broke the necks of around 50 carrier pigeons and then lit the cage on fire.