People in the south are being asked to report rook sightings during spring, when the pest birds are most active.
The Otago Regional Council’s delivery lead biosecurity coastal Otago Simon Stevenson said while rooks have been reduced to very low levels, there are 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.
“This enables us to better map nests and target these pests,” he said.
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. Rooks were introduced to New Zealand between 1862-1873 to control insects, and, like many other introduced species, their population flourished and spread.
In recent years, ORC and Environment Southland have worked together to eradicate the pests, with community help, which has pushed rooks down to very low numbers from many thousands of breeding pairs in the 1980s and 1990s.
“While we haven’t had reports of one for a few years now, should we discover an active nest we would likely use a drone to establish if the rooks are actively breeding or if it is just the male going through the motions of nest building, which they can do regardless of a mate.”
Environment Southland biosecurity team leader animals Dave Burgess said rooks are not currently known to be in Southland, with the last confirmed sighting in 2019.
However, there were populations in the mid-1990s to early 2000s in the Balfour, Eastern Bush, and Motu Valley areas. During the 2010s a small number of rooks were sighted in the Kaiwera/Pukerau area, which were thought to be transient birds from nearby Otago areas.
“As these are a very wary bird it is important people don’t try and shoot at rooks but report them to council so effective control options can be undertaken, at no cost to the landowner,” Burgess said.
Both councils use surveillance equipment to record and collect rook behaviour and age to build a picture of the current population.
What you can do if you see a rook:
•Report any rook sightings ASAP to the relevant regional council;
• Do not attempt to control any yourself, as unsuccessful attempts encourage dispersal and make rooks very wary and much more difficult to control.
