WELLINGTON-A mystery illness is decimating the chicks of New Zealand’s endangered yellow-eyed penguins, and scientists say they may have found the cause. The flightless birds, endemic to New Zealand, stand lower than knee-high, have pale yellow eyes and sport a band of yellow feathers around the head. There are about 2,400 of the adult birds left, according to estimates by New Zealand’s Department of Conservation. Their status is considered “threatened -- nationally endangered”. It is the country’s highest risk level. The mystery respiratory illness first appeared in 20 freshly hatched chicks brought to Dunedin Wildlife Hospital in 2019. “They were unable to hold their heads up, gasping with glassy eyes,” wildlife hospital director Dr. Lisa Argilla told AFP this week. “It was heart-wrenching to see these little chicks in such critical condition,” the veterinarian said. “All chicks that showed respiratory signs died -- there was nothing we could do to save them.” During the 2020 breeding season, a third of 150 yellow-eyed penguin chicks brought to the hospital died of respiratory problems, Argilla said. Professor Jemma Geoghegan, an evolutionary virologist, is part of a team of specialists investigating the illness. “The wildlife hospital tried everything in their power to prevent it but without knowing the cause it’s very hard to manage,” Geoghegan told AFP. Scientists tested tissue samples from dead penguin chicks with sequencing technology similar to that used to identify the coronavirus behind Covid-19. “There’s two diseases we have been investigating and we have found two viruses which we think are likely responsible,” said Geoghegan, a professor at Otago University. The team had identified a novel gyrovirus and a novel megrivirus, she said. Between them, the diseases are thought to have killed around 25 percent of yellow-eyed penguin chicks -- roughly 50 each year -- in recent breeding seasons, Geoghegan said.