Mr Rayner said he expected 20 to 30 people to compete in the national final, but many others were set to attend the event - including a busload of water-fowling enthusiasts from the South Island.
"Water fowling in New Zealand is more popular than rugby. In America, duck-calling is hugely popular and some people even make their living from the sport," he said. "Duck-calling is like playing any wind instrument, some people are okay at it and others become masters at it."
Paul Thomas from Whakatane-based Cupped Wing Calls, who is this year's chief judge, said these competitions were hugely competitive.
"Particularly when up for grabs is a free trip to America for the overall winner to compete in the World Duck-Calling Champs, which is held during the Maryland Water Fowl Festival in November."
Mr Thomas said the competitors were given one minute to sound out a series of duck calls - the hail, come back, feed chuckle, lonesome hen [calling out for a mate] and the routine call. The latter brought all the separate calls together in a sequence of calls.