"These are the culprits, they may be cute but they're dangerous," he said.
Mr Coker was first alerted about the killings by Environment Bay of Plenty, before he decided to set traps in the area to catch the pests.
"I think it's a good way to help Mamaku locals out and it helps protect the native birdlife in the area too.
"If this is what they're doing on someone's farm, imagine the damage they are doing out in the forests, to our native birdlife."
Since setting out five traps just over a week ago, Mr Coker has caught five ferrets.
Mrs Wilson praised Mr Coker for his efforts and said she was relieved to know the attacks were not the result of something more sinister.
"It's just such a relief, to know it was caused by an animal and not someone doing something silly and terrible. It's good to know."
Mrs Wilson said she will now lock her chickens in the coop at night to make sure ferrets cannot get inside.