A Norfolk man who illegally collected more than 5,000 rare bird eggs has been warned he is facing jail.
Daniel Lingham, 65, was reported to police by a member of the public who saw him "head-to-toe in camouflage gear" picking eggs up off the ground at Cawston Heath in Norfolk.
Norwich Magistrates court heard that officers attended and stop searched him on May 21.
The prosecution said he disclosed he had eggs on his person and produced two small tubs, adding officers also found he had a catapult and tree climbing spikes with him.
Lingham told the officers: "I've been a silly man, haven't I?"
- Click to watch a report by ITV News Anglia's Kate Prout
Officers searched his home address and found tubs containing eggs under his bed and in the kitchen and living room, with many of them handwritten on.
Ms Harper said officers found a total of 5,266 eggs of species including nightingales, nightjars, turtle doves, chiffchaffs, little-ringed plovers, woodlarks and kingfishers.
Lingham, of Newton Park Homes in Newton St Faith in Norfolk, admitted five offences under the Wildlife and Countryside Act 1981.
Prosecutor Colette Harper said that 75 of the eggs were protected under schedule one of the act, adding that "these species are in decline".
She said that in police interview Lingham claimed: "This is an addiction."
He was convicted of similar offences in 2005 when he was jailed for 12 weeks for illegally collecting 3,603 eggs, she said.
The charges to which Lingham pleaded guilty on Friday are taking nine linnet eggs at Cawston Heath on May 21 and possession of articles capable of being used to commit an offence found during the stop search, which are tree climbing spikes, binoculars and padded containers.
He also admitted possession of 75 schedule one listed wild bird eggs, possession of 4,070 ordinarily protected wild bird eggs and possession of articles capable of being used to commit an offence found at his home address, which were wooden receptacles, plastic containers and egg reference books.
Lingham told magistrates: "I didn't realise how many eggs there were. "I didn't count them."
Speaking outside court, RSPB senior investigations officer Mark Thomas described Lingham as a "one-man crime wave in terms of rare birds in Norfolk" whose actions had an "incredible impact on birds both regionally and nationally".
He said some bird species that Lingham targeted, such as nightjar, nightingale and turtle dove, have "really declined" in the last decade, some by as much as 90%.
The RSPB is spending nearly £200,000 per year trying to conserve the turtle dove as there is a "very high chance that this bird could become extinct in the UK", he said.
James Burrows, mitigating, said Lingham has been referred to a mental health team and is being treated for obsessive compulsive disorder.
Chairman of the bench Jeanne Heal, adjourning the hearing for a pre-sentence report, warned Lingham: "We're looking at a quite lengthy custodial sentence."
He was bailed to appear at Norwich Magistrates' Court on November 27 for sentencing.