People are being asked to report rook sightings during spring, when the pest birds are most active.
In a statement, Otago Regional Council Coastal Otago Biosecurity delivery lead Simon Stevenson said while rook numbers had been reduced, there were still some occasional sightings.
"We need the public’s help to target the last remaining birds, bearing in mind the potential always remains for the population to increase again," he said.
"This enables us to better map nests and target these pests."
Rooks are part of the crow family and are large birds with glossy, purplish-black feathers. They can be differentiated from other birds, such as magpies, by their larger size, their distinctive kaah call, slow wing flap and their wariness of people.
Rooks are attracted to recently cultivated paddocks and will feed on newly sown crops, causing significant damage.
