Scientists Reveal The Cause Behind 137 Yellow-Eyed Penguin Deaths

By Hannah Lozada

The cause behind the 137 yellow eyed penguin chicks (hoiho) that were brought to Dunedin Wildlife Hospital was originally a mystery. Thirty-one of the week old hoiho chicks showed signs that they had a respiratory disease. Twenty-seven chicks died within 12 to 24 hours while previously showing signs of symptoms. One survived for five days before it passed away. Only three chicks fully recovered and returned back to their nests. 

These deaths happened last year in 2021, during the hatching season between November and December. Recently, scientists have discovered the cause of the deadly respiratory disease that caused the endangered population to plummet. 

The yellow-eyed penguin is very special to New Zealand and is believed to be one of the rarest penguin species in the entire world due to its distinctive features and low population. They are also the last species remaining in its genus. In 2019, there were only four-thousand to five-thousand mature yellow-eyed penguins left. 

A new study was led by postdoctoral researcher Dr. Janelle Wierenga and virologist Dr. Jemma Geoghegan. They have concluded the cause of death was a gyrovirus that was responsible for the respiratory disease that  lowered the population. 

Ribonucleic acid (RNA) was researched from tissue samples from forty-three of the dead chicks. Geohegan stated that there was a, “highly abundant gyrovirus,” that was discovered in the RNA. This gyrovirus is known for spreading in other birds, and was recently identified in 2019. However, there were already records of this virus from 2015. Geohegan also concluded that the penguins died of, “Respiratory Distress Syndrome,” and that they used, “next generation technology to try and identify any pathogens present.”

 “This is the same technology that Chinese scientists used to identify a new coronavirus that was causing a respiratory disease in humans, which was later named SARS-CoV-2 (COVID-19).” (Geohegan)

The team created a polymerase chain reaction (PCR) test to see if the virus will be present in the future. This virus could potentially wipe out more endangered yellow-eyed penguins. 

Dr. Geohegan stated that between 2020 and 2021, “the number of chick deaths from this disease increased compared to 2019, with a mortality rate of more than 90%,” She continued, saying, “The disease has only been noticed in the last few years, meaning it is a new virus in hoiho. This means the virus would have likely come from another animal, maybe another seabird, to hoiho recently.” 

The northern population of yellow-eyed penguins located in New Zealand and Stewart Island has decreased by 75% within the last 30 years. The lack of food, predators, and diseases like the new gyrovirus are contributing to the penguin’s downfall. If something isn’t done soon, the Yellow-Eyed penguins may go extinct permanently.

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