The Royal Society for the Protection of Birds has offered a £1,000 reward for information leading to a conviction after four birds of prey were found dead in Staffordshire.

The appeal follows three separate incidents over a three-week period during the Coronavirus lockdown.

The incidents came in May and June, when three peregrine falcons and a common buzzard were found dead in various locations around the county.

As there were no visible signs of injury, and following contact with Natural England the birds were submitted for post mortem examinations and toxicology tests to establish the cause of death as part of the Wildlife Incident Investigation Scheme. The scheme investigates the death or injury of wildlife and companion animals that may have resulted from pesticide poisoning.

The results show that all four birds of prey were illegally poisoned by the same pesticide, and that at least two of the incidents involved a pigeon bait which had been laced with the pesticide.

A police investigation into the circumstances is underway as all birds are protected by the Wildlife and Countryside Act 1981. To kill or injure one is a criminal offence and could result in an unlimited fine and/or up to six months in jail.

Officers are asking local residents to report any suspicious behaviour they may have witnessed in the days leading up to the discovery of the birds and to continue to be vigilant for the signs of criminal activity, including dead or injured birds, poisoned bait and traps.

Detective Inspector Tim Boulton, of the Staffordshire Police Rural and Wildlife Crime Unit, said: "To find out that these birds have been deliberately targeted and poisoned is truly dreadful. We are working to ensure those responsible are identified and brought to justice.

"It is extremely concerning that a harmful substance has been placed in the countryside putting not only wildlife, but also people and pets at risk too.

"If a member of the public comes across a dead bird or suspicious object, please do not touch or move anything. Please take photographs if you can and make a note of your surroundings and landmarks to help officers to locate it. Every piece of information may be crucial in prosecuting an offender.

"Any information, no matter how small and insignificant it may seem, could help with our on-going investigation. Someone out there knows who poisoned these birds, so please do the right thing and get in touch with the police directly or any of our specialist partners."

Mark Thomas, RSPB Head of Investigations, commented "Peregrines are the fastest birds in the world, yet all too often the lives of these magnificent creatures are cut short by illegal persecution like poisoning.

"If you have any information about any of these cases, or if you come across what you believe may be a poisoned bird of prey, please call the police immediately. You are our eyes and ears."

Dave Slater, Natural England's Director for Wildlife Licensing and enforcement cases, said: "Raptor persecution is a national wildlife crime priority and a priority for Natural England. We are a committed partner with the Police and NGOs in tackling these despicable crimes. We would urge anyone witnessing or suspecting persecution to contact the police."

Anyone with any information is asked to call one of the services listed below;

• Staffordshire Police: 101 quoting incident number 232 of 16 May. You can also report online at www.staffordshire.police.uk/report or by sending a private message to Staffordshire Police on Facebook and Twitter.

• Crimestoppers: 0800 555 111

• RSPB's confidential Raptor Crime hotline: 0300 999 0101

• Wildlife Incident Investigation Scheme hotline: 0800 321600