Thieves snatched 60 racing pigeons, which are worth a considerable amount of money, after breaking into a shed at an allotment site in Doncaster.
The owner of the birds has been left distraught after the incident.
Police are appealing for witnesses to the theft which happened on land off The Oval in Dunscroft, between 4.45pm on Friday October 18 and 9.30am the next day.
The suspects involved in the incident damaged a fence and also forced a lock on the shed in order to get to the birds, which are owned by a 54-year-old man from Stainforth.
All of the pigeons which were taken are described as being of mixed colours, but they can be identified with their leg rings, which all feature the unique serial number DY2008.
Officers believe the suspects would have taken a long time to remove the birds in boxes.
They will have either takeng them to a vehicle or walked off with them.
PC David Connolly, from Stainforth Safer Neighbourhood Team, said: “These are racing pigeons which, if sold, are worth a considerable amount of money.
“The owner is understandably distraught by the theft and I would urge anyone who has been offered the birds for sale, or who has any information about the theft, to call police immediately.”
Witnesses or anyone with information should call South Yorkshire Police on 101, quoting incident number 409 of 19 October.