A joint Otago Regional Council (ORC) and Environment Southland approach has pushed rook numbers down to an estimated 40 in the Otago and Southland regions, a far cry from the many thousands which were breeding in the 1980s and 90s.
Rooks were brought to New Zealand between 1862 and 1873 to control insects, but like many other introduced species, their population rapidly exploded.
Over the years, the councils have been working together to eradicate the pests, with help from the community.
The potential remains for rook population to flare up again.
For this reason, ORC coastal Otago biosecurity delivery lead Simon Stevenson is asking the public to keep reporting sightings this spring, when rooks are most active.
‘‘This enables us to better map nests and target these pests,’’ he said.
‘‘We really appreciate the support from the community for our programme over the years.
‘‘It has gone a long way towards the success we have experienced.
‘‘It shows the success we can have eradicating other pests listed in our plan, for example wallabies,’’ he said.
Rooks are often mistaken for crows — which New Zealand does not have — as they are both corvids.
They are larger than magpies and completely black, and their feathers can have a purple or bluish›purple sheen in bright light.
They can also be identified by their harsh ‘‘kaah’’ call.
They live in large ‘‘parliaments’’ in historic nesting sites in the Maniototo, Middlemarch, Strath Taieri, and South Otago around Clinton, Kaiwera and Clydevale.
Rooks eat fields of cereals at all stages of growth as well as other recently sown seeds.
The councils said support from the community to report rook sightings was vital.
TheORCand Environment Southland control programmes have relied on public sightings and this year they may confirm suspicions that there is no longer a breeding population of rooks in Otago.
Spring is the best time to spot rooks because it is when they nest.
People are asked not to attempt to shoot at or scare rooks themselves, as there is often only one chance to deal with them.
If they are frightened they can scatter and form new rookeries.
‘It shows the success we can have eradicating other pests listed in our plan, for example wallabies’