A kākāpō chick has had its life saved after undergoing the world's first ever bird brain surgery.
The chick, known as Espy 1B, was born in the wild on Codfish Island and was in the care of the Department of Conservation's (DoC's) kākāpō recovery team.
Rangers noticed an unusual lump on Espy's head, and sent him to Dunedin Wildlife Hospital for a CT scan. There, it was discovered his skull hadn't fused properly.
"The chick was hatched with a hole in its skull that allowed part of the brain and dura (the tough barrier around the brain) to herniate out," said Massey University's Wildbase Hospital director Professor Brett Gartrell.
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"In humans, this spot fuses after birth, but this is highly unusual in birds as the skull has finished fusing prior to hatch."
The concern was that Espy's soft spot left him open to trauma and infection.
Kākāpō are critically endangered, so there was only one thing for it - it was time for Espy to have brain surgery.
Espy was transported to Wildbase Hospital, and last Monday a team of veterinarians and veterinary technicians led by Professor Gartrell carried out the risky surgery.
The team opened up Espy's skull, and removed the herniated brain barrier. They then removed a tiny piece of his brain, and fitted a small synthetic mesh over the open brain. The mesh was infused with bone marrow, and Espy was fixed.
Professor Gartrell described the surgery as "intense" but Espy has made a startling recovery.
Now 56-days-old, Espy is now growing and developing well.
Later this week, he will be transferred back to Dunedin Wildlife Hospital so he can be paired with another baby kākāpō to be released into the wild, without imprinting on humans.