The Otago Regional Council says it is close to eradicating a pest bird from the region.
Rooks can destroy crops and new grass paddocks in a couple of days and are a problem throughout New Zealand, but are more prevalent in grain-producing regions in the south.
The Otago Regional Council says its eradication programme has reduced numbers from 5000 to less than 100 over the past six years.
Director of regional services Jeff Donaldson says he expects the region to soon be rid of the distinctive rook's caw.
He says the 100 birds that are left do still tend to nest, but often it seems to be the males that are nesting and often there are no young in those nests.
Mr Donaldson says it is important that people who spot a rook don't try to shoot it, as that spreads the birds making them harder to locate. They should instead contact the council.
Rooks are nesting and over the next month the council will use a helicopter with a staff member dangling below to place poison in the nests.