A pensioner was fined £4,700 after being found with hundreds of protected bird eggs.
William Beaton, 73, from Devon, admitted stealing eggs from across the country.
He pleaded guilty to taking Barn owl eggs in Norfolk and the eggs of other protected birds in Orkney.
Plymouth Magistrates' Court heard he was found in possession of 435 eggs at his home in Burrator Road, Dousland, near Yelverton.
He admitted fives offences under the 1981 Wildlife and Countryside Act.
Howard Jones, RSPB investigation officer, said Mr Beaton had shown a "a worrying trend" of targeting rarer species in recent years.
He added: "The conservation impact of these actions cannot be underestimated and the public should be aware of people behaving suspiciously around nest sites during the breeding season."
The eggs will be sent to Natural History Museum.