A pigeon has died after a teenager pulled it from a tree and ripped off part of its wing, the RSPCA said.
The animal welfare charity said the boy attacked the bird in Walthamstow, east London, at around 11.30am on Sunday.
A passer-by saw the teenager on a silver scooter grab the wood pigeon on a low tree branch and then try and pull its wing off.
The witness stayed with the dying pigeon in Sandpiper Close and reported the incident to the RSPCA which later rescued the bird but was forced to euthanise it.
The charity has now launched an investigation and is appealing for help identifying the teenager responsible for the "mindless attack".
Animal rescue officers (ARO) arrived at the scene shortly after the attack and could see the bird hiding behind a fence near the tree with a badly broken wing.
ARO Nicole Thomas, from the RSPCA, said: “When I arrived at the scene there was blood and feathers on the street and the poor bird was hiding behind a nearby fence and was obviously terrified and stressed.
“I managed to capture the bird but the damage was so bad the kindest thing to do was to put the pigeon to sleep.
“The poor bird was happily feeding when this youth came along and just grabbed it from the tree and carried out such a mindless attack on a defenceless animal."
The RSPCA wants to hear from anyone who may have seen the incident or who may know who is responsible.
The charity is also keen to hear from anyone with CCTV in the area which might help the investigation.
Thomas said she believed as the boy was on a scooter he would likely live locally.
The suspect is described as a young teenager, white, with dark hair, wearing a tracksuit and was riding on a silver scooter.
Anyone with information can contact the RSPCA appeals line on 0300 1234 999.