Vets in New Zealand have performed world-first brain surgery on a critically endangered New Zealand bird, as efforts intensify to save the vulnerable kākāpō population.

There are just 147 adult kākāpō alive today and conservation efforts to boost the population are scaling up in New Zealand, which has more extinct and endangered birds than any other country.

A few hundred years ago kākāpō were one of New Zealand’s most common birds, before being hunted to the brink of extinction, killed by introduced pests, and losing their forest homes to farming.

They are also the largest, heaviest parrot in the world.

Now, vets have taken extreme steps to save the life of a 56-day-old chick named Espy-1B who was born with a life-threatening skull abnormality.

Adapting surgical techniques used on humans and mammals, a specialised team of surgeons was assembled to try to save the young bird’s life.

Kākāpō chick Espy-1B Photograph: Massey University

Director of Wildbase Hospital Professor Brett Gartrell said the surgery was a world-first and had never been attempted before in the realm of avian medicine.

“The plates of its skull had not completely fused and the fontanelle was still open,” said Gatrell, meaning part of the chick’s brain had herniated out of its skull.

“This condition could be life-threatening for the critically endangered bird, so action needed to be taken.”

Veterinarians from Auckland Zoo, Wellington Zoo and Dunedin Wildlife Hospital planned the surgery, and the country’s national airline transported the chick for free.

“This is a risky surgery and the common complications for this surgery in humans include permanent brain damage, continued leakage of cerebrospinal fluid and the possibility of meningitis,” said Gatrell, who described the operation as “intense”.

A week on, the surgery has been deemed a complete success by the team, with Espy – 1B now well enough to return to his home at Dunedin Wildlife Hospital in the South Island, where it is hoped he will thrive and eventually breed.

Espy is one of 76 kākāpō chicks that have hatched this year in a record-breaking breeding season for the critically endangered bird. But in the weeks since the high birth rate was reported with joy by conservation staff a number of chicks have died.

