It is feared the haul may include eggs laid by rare birds such as ospreys
A man has been charged with wildlife crime offences after police seized more than 5,000 eggs during a raid on a home in West Lothian.
Equipment used by egg collectors was also taken from the property in Torphichen, near Bathgate.
A 57-year-old man has been reported to the procurator fiscal.
It is feared that some of the eggs could be from rare species such as the golden eagle, red kite, osprey and peregrine falcon.
Lothian and Borders Police, Tayside Police and Royal Society for the Protection of Birds (RSPB) worked on the case.
They have not identified the species of eggs included in the collection.
However, it is believed that it will represent a "vast spectrum" of UK species.
A spokesman for the RSPB said it was battling to "subject egg collectors to the full force of the law".
He said: "The evidence that has been gathered is being sifted through to establish the full facts and, with a collection of this size, that will take some time.
"The police are now progressing this as a criminal investigation.
"First and foremost this type of activity is illegal and for a good reason, as it impacts on the ability of breeding birds to maintain their population levels.
"Egg collecting belongs in the past and there has been good progress in consigning it to that era.
"However, there are a hardcore of people who exist that are continuing the practice.
A spokesman for Lothian and Borders Police said: "A house in Torphichen was searched and over 5,000 eggs and egg collecting paraphernalia was seized.
"A 57-year-old man has been reported to the procurator fiscal."