Enquiries are being made after a freezer filled with dead pigeons was found in a back lane.
Staff from Darlington Borough Council were called out to remove the chest freezer from the rear of Roseberry Street and Greenbank Road when they discovered it contained dozens of dead birds.
It is believed the freezer was dumped on either Tuesday 8 November or on the morning of Wednesday 9 November.
The council is appealing for any information people may have about the discovery.
Mike Renton, cabinet member for stronger communities, said: “It really is quite horrifying that anyone could do such a thing, and we are determined to catch those responsible and prosecute them.
“We would urge anyone with any information to let us know. Anything you tell us will be treated with absolute discretion, but we need your help to put a stop to this!”
The council wants to hear from anyone who might have information about the incident.
Anyone who can help with enquiries is asked to contact email@example.com or call 01325 406999.
Want a quick and expert briefing on the biggest news stories? Listen to our latest podcasts to find out What You Need To know...