Traffic on the A4042 at Llanellan was brought to a standstill after the plastic bath toys escaped from their transport near Abergavenny.
Around 100 ducks spilled onto the road after the boat trailer they were in opened in transit.
Tony Pugh, part of the team that rescued the escaped ducks, told local reporters: “I can laugh now but earlier I had to run down the road kicking the ducks to the side and then collecting them.
“A car pulled up and a child nicked a few so we’ve lost some.”
Mr Pugh, 69, added that it had taken him around an hour to collect all the ducks that hadn’t been stolen.
Gwent police reported the incident around 10am, and helped to clear the plastic birds from the carriageway.
The ducks were en route to a race at Llangynidr, in Powys, set up by the Monmouthshire, Brecon and Abergavenny Canals Trust.