While stopped at a traffic light in South Deerfield last week, I looked in my rearview mirror and saw this scene: plumber Frank Marchand, right, with his apprentice, Ian Lesko, and Marchand’s collection of ducks on his dashboard.

I pulled over and let Marchand pass so I could follow him to his next stop, which I discovered was his plumbing shop a few minutes away.

Marchand said his collection, which has grown to hundreds more than the 70-80 he has displayed on his dash, started about 30 years ago. It was a period of torrential rains, he said, and his phone was ringing around the clock with flooding problems. Though he tried to convince callers that the water would subside on its own, many still insisted he pump water from their basements. While heading out the door for another day of pumping, he looked at his son’s toy box and decided to grab a duck from it. While pumping out a basement, he threw the duck into the water.

“Oh, so you think this is funny, throwing a rubber duck into the water,” Marchand recalls the owner saying. Marchand assured him the duck had a purpose: When the water was finished draining, the duck would be sucked close to the pump and he would know the job was done.

He placed the duck on his dashboard, and his collection grew from there. All have been given to him. He remembers returning to his van while on a call in Northampton and finding two ducks stuck in each door handle.

A plumbing inspector gave him the large one centered on his dash.

He said sometimes while at a traffic light, the car in front of him doesn’t move on a green light, and he realizes they are looking at his collection.

“I’m holding up my own traffic,” he said.

Children in school buses crowd to the back for a look.

“Kids love them,” he said.

 Now he keeps a box of ducks in his van and lets the children of his clients pick one.

“It puts smiles on people’s faces, and it costs nothing,” he said.