North Shore residents say somebody is poisoning hungry sparrows and leaving them to die on roads and footpaths.
Browns Bay resident Kate Mitchell said she found about six birds "stumbling around on the ground" on Clyde Rd on Saturday evening.
"They looked like they had been poisoned, so I got a box and collected them all and took them to the SPCA."
She was told the birds had been given a drug that made them sleepy and once unconscious they froze to death overnight.
Ms Mitchell said about 10 children were on the street when she came across the birds.
"Some of them had stopped to try to help the birds and they were upset."
She said some of the residents were under the impression the Auckland Council had given permission for local businesses to poison the birds, but a council spokesman said this was not the case.
Council spokesman Nigel Horrocks said the poisonings were "news to us".
"Until we know what the story is, it's very difficult to know whose responsibility it is or whether it's a criminal offence or whether it's a council offence."
Businesses in the area denied any knowledge of what had happened.
Sylvia Durrant from the SPCA's Birdwing in nearby Rothesay Bay said the poisonings had been going on for a couple of weeks. On Saturday night 10 sparrows were brought into her.
"When sparrows become a nuisance and get into food and stuff, eventually someone gets sick of them and decides to get rid of them."
She believed people used a chemical called alpha chloralose, often used by pest controllers.
"This goes on all the time, but somebody's been very insistent down in Browns Bay."
If anyone found birds "acting dopey" they could take them home, give them water and keep them warm in a box or cage.By Rebecca Quilliam Email Rebecca