During summer, when soil becomes hard and difficult to extract insects, rooks assemble into large groups and target easy food supplies. These include walnut stands, acorns, freshly ploughed soil (for unearthed insects), newly germinating crop seedlings and mature grains such as wheat and lentils. Precision planted crops such as maize, peas and beans are especially at risk.
Rooks are large black birds which are active during the day. They can be identified by their harsh ‘KAAH’ call. Rooks nest in colonies of 20 to 100 pairs, and up to 900 pairs in heavily infested areas. Rookeries in the Wellington region typically contain up to 20 nests. The first colonies to establish in the Wellington region were in southern Wairarapa in the 1930s. From 1985 to 1994 rook numbers in the Wairarapa increased tenfold until Greater Wellington commenced control in 1995. Currently, rooks are mostly confined to northern Wairarapa. In the absence of control, rooks are expected to increase their numbers and extend their range into the remainder of the region.
Rooks are most commonly sighted nesting in large trees, or feeding in flocks on pastoral or cropping land. Rooks are highly intelligent birds, and individual occupier attempts to control rooks can result in scattered rookeries and an eventual increase in rook numbers. If a new rookery is sighted or a number of birds seen regularly feeding in a paddock, contact Greater Wellington and let us know.
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