Kea attack sheep in low numbers, study finds

Friday, 1 November 2019

Kea are one of New Zealand's favourite native birds, but they have a vicious side.

Kea attacks on sheep have been measured for the first time.

About 0.5 per cent of sheep at five South Island high country farms were attacked by the alpine parrots, according to just published research by wildlife scientist and kea specialist Clio Reid and colleagues.

It was the first time 'kea strike', as these attacks are known, has been quantified, she said.

'This study showed that kea strike on sheep was occurring at a low prevalence on the high country farms surveyed. The wounds identified were survivable.'

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While there are millions of sheep on the South Island, there are only 3000 to 7000 kea (Nestor notabilis) left and they are largely confined to high alpine areas.

Reid and colleagues examined 13,978 sheep on the five farms and found 76 wounds attributed to kea strike on 70 sheep.

The researchers generally examined the animals immediately after shearing and looked for old and recent wounds.

The researchers examined 13,978 sheep and found 76 wounds attributed to kea on 70 sheep. Photographs of kea attacking sheep are rare.

The guts of the study was deciding which wounds were 'consistent with kea strike' and which were shearing wounds or other types of trauma.

Puncture wounds were discarded, for example.

To classify the gashes or scars, the researchers relied on historical and recent photographs and descriptions of kea strike wounds. They also consulted with farmers and shepherds who were familiar with kea strike.

'The majority of shearing wounds that we observed were very fresh, and older shearing wounds were easily discernible from wounds that we attributed to kea strike,' the authors wrote.

Kea strike injuries were distinctive, jagged and looked like a 'predator had a go at the sheep,' Reid said in an interview.

An older healed wound about 15 cm long on a sheep.

'We were able to confidently distinguish these wounds from shearing wounds, puncture wounds, and dermatophilosis' (a bacterial infection), the authors wrote.

They also ruled out attacks by other bird species and dogs, largely because the wounds and their locations were inconsistent with attacks by those animals.

Sheep, farmers and kea have a lousy history. Due largely to fears about kea strike, farmers were encouraged by the government to kill them and paid a bounty on about 150,000 dead kea between the 1860s and 1970.

Almost full protection was mandated in 1986.

While the true nature of these attacks was not understood, Reid speculated that the curious and intelligent birds alighted on the animals' backs to investigate them.

The sheep often startled and ran. The birds clung on with their claws, causing a wound. The birds then discovered that sheep flesh could be eaten.

It's possible the attacks were more like hunting, she said, and it's possible males were taking food back to females on a nest when food was scarce.

We are confident that kea strike is the most probable cause of these wounds in sheep, the researchers wrote.

Reid did not witness any attacks. They generally happened at night, in winter, in mountainous terrain, and on large farms – 8000 to 19,000 hectares, in this study. An international rugby pitch is about 1ha.

Kea strike was 'sporadic [and] unpredictable'.

These factors also prevented her from measuring sheep deaths caused due to kea strike, whether directly or later infection.

The authors cautioned that this was a 'preliminary study' and acknowledged a 'lack of definitive evidence'.

But 'we are confident that kea strike is the most probable cause of these wounds', they wrote.

Reid has been studying kea for about 15 years. With others, she showed many kea had elevated lead levels in their blood, probably from nibbling paint, flashings and nail heads on back country buildings.

DOC and the Kea Conservation Trust now have programmes to remove lead from kea habitat.

Reid was awarded a PhD for this work from Massey University. The field work was done in 2012-13 in Whakatipu-Queenstown areas of central Central Otago.