At 12cm long and weighing 14 grams, the goldfinch is a prime target for sparrowhawks and other predators in the avian world.
But their sweet song and bright plumage has also made the tiny songbird prey to bird baiters who are entering urban woodlands with pots of glue to catch the birds, which they can then sell for up to £100 a time. The practice is becoming prevalent in east London, particularly among north African communities where having a songbird in the home is a tradition.
The methods employed to catch the birds are particularly cruel. The hunters put a bait bird in a cage in a bush or tree before smearing the branches with rodent glue.
When the bait bird sings it attracts other goldfinches, who flock to inspect the intruder in their habitat. When they land on the branches they become stuck in the glue. Too tiny to free themselves, they can later be plucked off by the baiters.
As goldfinches are particularly territorial they can refuse to sing when in an unfamiliar bush. To combat this, some baiters will burn out the bait bird's eyes with a hot needle so it is no longer aware of its surroundings.
Catching wild birds in Britain is illegal. Sergeant Rowan Healey, of Scotland Yard's wildlife crime unit, said: "In the Sixties and Seventies birds like these would be sold in pubs in East London. But as people in this country have become more environmentally aware we don't do that anymore.
"These birds are caught in places like Walthamstow Marshes or the Lea Valley and are sold from cages outside shops. The fact that they are on display makes it clear that some members of those communities are not aware that catching and selling the birds is illegal.
"We need to educate the public that this is a crime. Even if people buy these birds innocently they are inadvertently breaking the law and could be prosecuted. The key thing to look for is a solid metal ring around the ankle. If it does not have one then it is a wild bird and is illegal to buy."