Could cheeky weka help eliminate New Zealand’s big pests?

With a penchant for running away with the belongings of unwitting vagrants, Weka rivals Kea for our most daring native bird.

Now, researchers have discovered that flightless scallywags may have another unlikely role in nature: pest destroyers.

A new study, published in the New Zealand Journal of Ecology, found that rats, mice, and even rabbits have been registered as weka tucker.

“The Maori sometimes introduced weka to offshore islands as a form of rat control,” said study leader Dr. Jo Carpenter, a postdoctoral researcher at Manaaki Whenua – Landcare Research.

“And some European settlers agreed that weka did a better job of controlling rabbits than introduced stoats and ferrets. It is possible that weka may play a role in suppressing some invasive mammals today.”

Carpenter and his co-authors examined reports and articles to compile a comprehensive list of weka foods, and found that several studies had recorded rodents and rabbits consuming weka.

Their findings suggested that weka could be a valuable tool for sanctuary ecosystems such as Zealandia and Maungatautari, which experience large increases in mouse numbers following eradication of rats and stoats.

But the tendency of the weka to feed on both native and introduced species makes them controversial to conservation professionals.

“Ecosystems often exclude weka, because they are concerned about the impact that weka may have on other threatened native species,” said study co-author John Innes, also from Manaaki Whenua.

“Conservation practitioners need a detailed understanding of the role of the weka in New Zealand’s ecosystems, so that the benefits of reintroducing them can be balanced with its potential negative effects on other threatened animals.”

The team also reviewed all the evidence that weka eat native species.

They found that while weka had been recorded to eat native lizards and the eggs and chicks of ground-nesting birds, very few studies had measured whether weka had actually caused a decline in the populations of these animals.

“We need more studies that really measure the density of species with and without weka, so that we can understand if they are likely to have negative impacts on certain species,” Carpenter said.

“Historically, our native animals evolved and coexisted with weka and other native predators, such as Haast’s giant eagle.

“But now many native species, including the weka, have been severely depleted by introduced mammalian predators. This means that some populations of native species may not be able to resist native predators at this time.”

Ultimately, however, the study showed that the Weka are an important part of New Zealand’s unique ecosystems and should be restored to their native range whenever possible.

“Weka is charming and cheeky,” Innes said.

“Thus, weka restoration may provide an opportunity to restore lively relationships between people and native birds, as well as possibly offer some pest control benefits.”