Armed police arrested a man in Burgess Park on Sunday morning after reports of shots being fired at ducks in the lake.
Officers also seized an air rifle after being tipped off that two men were targeting the birds at around 9am.
Southwark neighbourhood inspector, Tom Cornish, said it is possible that one duck had been killed in the attack but this was so far unconfirmed.
A dispersal zone had been put in place in the area over the weekend after reports of a planned illegal rave in Burgess Park.
A Section 35 Dispersal Zone has been authorised between 1400hrs on 26/06/2020 and 1400hrs on 28/06/2020 covering Burgess Park and the Aylesbury Estate. This is in response to information received about a possible unlicensed music event. pic.twitter.com/v8JguDr5Wp
— MPS Southwark (@MPSSouthwark) June 26, 2020