Search begins again for elusive rooks

Rook numbers are likely on the rise after escaping control last year due to COVID-19 restrictions.

With spring just around the corner, Waikato Regional Council is asking landowners to report rook sightings for targeted pest control to prevent them from becoming a problem on farms.

Biosecurity pest animals team leader Brett Bailey said two nesting sites were confirmed near Hinuera and Paeroa last year. However, control was unable to take place due to being in lockdown during the nesting season.

“We’ve had new sightings reported from north Waikato and south Auckland areas, which suggests rooks are heading north,” said Mr Bailey. “Usually our hotspots are Paeroa, from Te Poi to Matamata, Mangakino to Taupō, and in Hamilton. We’ve had reports of rooks around Whakamaru and Mangakino that we’ve not been able to locate either.”

Before the 2021 breeding season, it was believed that rook numbers in the Waikato region were below 40.

Mr Bailey said the council relies on landowners to let them know where rooks are nesting because otherwise it was like looking for a needle in a haystack.

“It’s a good time of the year to start seeing rooks as it’s breeding season, which is when they congregate together. It’s important that landowners don’t try to get rid of them themselves, because we don’t want to scare them and make them fly away and nest somewhere else.”

Once rookery sightings have been called in, a drone is used to survey for the presence of eggs and/or chicks in nests to ensure only active nests are treated.

Rooks generally build nests in pine or eucalyptus trees. The largest colony ever found in New Zealand was nearly 1000 nests but, thanks to control, such groupings are a thing of the past.

The regional council has been controlling rooks since 2002, when their numbers were around 200.

Rooks were introduced to New Zealand in the 1860s to control insect pests. However, in large numbers, rooks can destroy newly sown crops and pasture by tearing them up in search for grubs.