Wild birds are being snatched from gardens and fields across Kent before being sold illegally.

Goldfinches, chaffinches and other attractive small birds are being caught using traps, nets and GLUE in what police are describing as a network of organised crime.

PC Michael "Geordie" Laidlow from the police's rural partnership team is one of six Kent officers dedicated to dealing with wildlife, environmental and heritage crime.

He said: "The theft of wild birds seems to be on the increase throughout Kent. It's something we come across quite often. There are networks of thieves operating across the county – I would call it low-level organised crime.

"We've seen people contacting each other on social networking sites such as Facebook to arrange the illegal buying and selling of these birds but mostly it’s done by word of mouth and face to face meetings."

Some criminals use baited cages to catch the birds while others string "mist nets" – large swathes of fine mesh netting that is difficult to see – between trees to catch the birds in flight.

Perhaps the cruellest method involves covering sticks in a glue-like substance known as birdlime and inserting them into bird feeders.

In scenes reminiscent of Roald Dahl's children's book The Twits – where Mr and Mrs Twit spread Hug-Tight Sticky Glue on tree branches to catch birds for their dinner – finches and other creatures land on the twigs and become stuck.

PC Laidlow added: "It's not like superglue, but it is sticky enough for the birds not to be able to get their feet off. It is cruel. If the captors don't come back quickly enough the birds die a horrible death from starvation."

A couple from Kingsnorth in Ashford experienced the theft of goldfinches first hand as thieves set traps near their home.

The woman, who asked not to be identified so as not to alert the thieves to where the birds were, had feeders full of niger seed stolen from her garden to be used as bait.

She said: "It possibly started last year. I saw two bird feeders beside a path near our house and thought: 'That's nice, someone is feeding the birds.'

"We hang a niger seed feeder on our seven foot high fence. The feeder is not visible from outside the garden and we keep our gate locked.

"The feeder vanished one afternoon and we found it hanging from a tree outside our garden.

"When retrieving it we found thin plastic sticks, covered in a very sticky substance, pushed in either side of the perches and feed holes. We found out goldfinches are being illegally trapped and are then sold if not too badly mutilated.

"We have since hung two more feeders out in different places and they have gone within a few hours, in daylight, when we've been at home. We are not too bothered about the loss of feeders but about what is happening to the birds."

The couple reported the thefts to the RSPB.

PC Laidlow would not say how much an individual bird could fetch on the black market, but revealed it was a significant amount.

He said any birds that "look pretty" are being targeted.

PC Laidlow added: "Most breeders are sensible and stick to the law but some crossbreed wild birds with their captive ones to improve their DNA.

"When we search a property we often find traps. We have successfully prosecuted people for stealing wild birds and we often work with the RSPCA, vets and bird experts when doing so. We had a successful prosecution last year when we caught a thief red handed walking away from a trap with a bird in his pocket."

PC Laidlow advised: "People should carry on feeding the birds as normal but just be on the lookout for tell-tale signs such as sticks, nets, little cages or anything that looks out of place."

The RSPB said it was aware of wild birds being captured illegally across Kent and advised people to report anything suspicious to the charity or the police.

Spokesman Rolf Williams said: "We want to hear from people if they have any evidence of this sort of crime happening near them. We always work with local police wildlife officers and we would urge people to report any suspicious activity to us or police.

"Even if the police can't come out every time the reports will help them build up a picture of where the thefts are taking place so they can home in on the perpetrators."

Report wild bird theft to police by calling 101 and asking for a message to be passed on to a member of the rural partnership team. Report a wildlife crime to the RSPB by clicking here.