Police are looking for a man who kicked a newborn cygnet out of his way while jogging instead of going around the young swan.
The “desperately poorly” bird is feared to have brain damage and is being cared for at a nearby sanctuary following the incident in London’s Richmond Park.
Met Police officers for the Royal Parks have issued an appeal for witnesses.
They says the suspect is a white male around 60 years old, 5ft 6in, and was wearing black running shorts and a vest at the time.
The incident happened around 5.30pm on Monday at the Pen Ponds area in the middle of the south-west London park.
Police said they had spoken to staff at the Swan Sanctuary, based in Shepperton, Middlesex, who said the cygnet is “still desperately poorly”.
“Unfortunately it’s not looking good for the cygnet,” Royal Parks Police posted on Twitter.
But they added: “Thankfully he is in good hands.”
Any witnesses should call 07920 586546 and quote reference 0705738/20.