Regional councils are urging people around New Zealand to report sightings of rooks.
Report sightings but don’t do anything that might alarm the birds, such as shooting or disturbing nests. Rook groups will scatter if alarmed and that means they will be harder to find and potentially establish more breeding sites over a wider area. Rooks are very intelligent and wary of anything new or unusual. For instance, they have reportedly learnt to tell the difference between a gun and a stick and have been known to use a guard bird to test food before others in a flock will eat it.
Instead, note the location, try to take a photo if you can and report your observation to your local regional council as soon as possible. Prompt reporting will enable the council to follow up before the birds move on (perhaps to a new food source).
What to look for
Keep an eye out for large, glossy black birds, most likely in groups as rooks are not generally solitary. They can be found in rural and urban areas. Listen also for their distinctive ‘kaah kaah’ call.
Spring and summer can be a good time for sightings as breeding groups will congregate and be particularly noisy in the vicinity of their rookeries.
Their nesting sites, known as ‘rookeries’, are another sign to look for. A breeding colony will build a number of nests in one locality, often in large pine or eucalyptus trees. The nests tend to be large and twiggy.
Why are rooks a problem and how are they controlled?
Rooks are classified as an ‘Unwanted Organism’ in New Zealand. They threaten agriculture by destroying pasture, newly sown and young seedling crops. The damage can be particularly bad when the birds congregate in large flocks. It has been know for entire paddocks to have to be re-sown. Although less is known about their ecological effects, they can compete with and prey on native species.
In the regions where rook populations are well established long-term eradication is the objective and rook populations have been reduced in many areas. Other regions will also want to hear of possible sightings so that action can be taken to exclude rooks and prevent breeding populations from establishing. Rooks are most prolific on the east coast of the North Island south of Auckland. They are present in the South Island, in Canterbury, but in much smaller numbers.
As rooks are so wary, they are hard to control and control should be carried out only by experienced biosecurity personnel. Toxin applied by aerial methods directly into nests has been effective. The adult breeding birds come into contact with the poison when they visit the nest to feed the chicks and then ingest the poison when they preen.
Find out more about rooks and how to recognise their presence on our culprits page
Report a sighting > find your local regional council