A man wants customers to complain to Pak'nSave Kilbirnie after learning they shoot sparrows in their store.
Brendan Robinson was told by staff that birdseed and birdcalls were used to draw them down from the rafters to be shot.
He believed the birds suffered needlessly and that trap and release methods could be used more humanely.
"There's no one in the world who's 100 percent a clean shot, so that means those birds will suffer horrible pain.
"I imagine those birds fluttering, and there's probably a lot of suffering involved - and why cause suffering when you don't have to?"
He said the practice was "corporate laziness" and people upset by it should ring the supermarket's parent company, Foodstuffs, to complain.
A Foodstuffs spokeswoman confirmed the store hired a contractor to shoot the birds, which were a health threat.
She said it was not known what methods were used in the rest of its stores, but there were no company guidelines for pest control methods.
Foodstuffs head of external relations Antoinette Laird said there had been problems with increasing numbers of birds at Kilbirnie Pak'n'Save.
"Birds are a particular problem in our large supermarkets."
They had been "a significant source of customer complaints as the birds eat the produce, bulk foods and peck into the meat".
Some stores were investigating catch and release traps from the United States, but they were not readily available in New Zealand, Ms Laird said.
Earlier this week, a Dunedin woman complained about what she thought was a bird dying from poison in a Dunedin Pak'nSave.
Initially the company would not comment on what chemical was used, but now Ms Laird said the store drugged birds to capture them before setting them free.