Police have identified four teenage boys suspected of stoning a black swan to death in Moonee Ponds on Wednesday afternoon.

And Melbourne Zoo is to mount an operation to save the native bird's unhatched offspring - a lone chick currently in the care of a heart-broken male.

A male black swan continues to protect a nest after its partner was killed in a brutal attack. Credit:Craig Abraham

A police spokeswoman said witnesses came forward and identified the four boys.

Two teenage girls known to be with the boys were not thought to be involved in the attack.