Magistrate Eamon Lambert told him the court had seriously considered imposing a jail term. He said: “Your actions had a marked effect on the bird population and a serious impact on the environment.”

Maps and notebooks documenting egg-collecting trips with others around the UK will be seized and destroyed.

Roger Thomson, mitigating, denied suggestions his client had collected eggs while on duty.

Earlier, the court had heard the notebooks detailed visits to the Western Isles to steal golden eagle eggs, to south Devon to take Cetti’s warbler eggs, to North Wales to steal chough eggs, and to the New Forest to take hawfinch eggs.

Upson claimed to have stopped egg collecting but the evidence found indicated he was active between at least 1991 and 2001, the RSPB said.

The egg collection was found in an old suitcase in Upson’s loft, along with hundreds of egg data cards, which he had faked to suggest the collection was old.

Mark Thomas, RSPB investigations officer, said: “That a police officer should knowingly break the law in pursuit of this obsession is shocking, and we welcome his conviction. ”We are pleased with the sentence – it is fitting with the evidence heard.

“I don’t think he is an individual who will go back to egg collecting and thankfully egg collecting is becoming more and more unusual in the UK.”

A spokesman for Suffolk Police confirmed Upson had been employed by the force, most recently as a training officer.

Det Insp Jeff Yaxley said: “Public confidence in the police depends on those serving with us demonstrating the highest standards of personal and professional behaviour.

“Whilst it is always disappointing when an officer falls below those standards, the constabulary will continue to robustly investigate any allegations of criminal conduct by its employees.”