Two men jumped out a van and dumped five ducks in a car park.
Passers-by watched the men drive to an area behind the Co-op, in Bassett Avenue, Bicester, then dump the domestic ducks and drive off in a white Transit van.
Onlookers ushered the ducks to a safer area and called the RSPCA.
Inspector Andy Eddy said the ducks had been left in a “dangerous place” and could easily have been hurt by another animal or run over.
He said: “This is quite a bizarre incident and it is hard to understand why someone would dump five domestic ducks. It is also quite a strange area to leave them in.
“The ducks seem to be in reasonable health and they are with foster carers now.
“But it was a dangerous place to have dumped them and they could have easily gone on to the road or been attacked by another animal.”
He urged anyone with information about the incident, at 1pm on Wednesday, April 11, to call the RSPCA cruelty line on 0300 1234 999.