Protecting precious hoiho from a deadly disease

On the windswept coast of the Otago Peninsula survives some of the world’s rarest penguins – the hoiho or yellow-eyed penguin. In late 2022, two of Auckland Zoo’s skilled bird keepers travelled to the region to assist with the Department of Conservation (DOC)’s recovery efforts for hoiho – who are sadly teetering on the brink of extinction.

This iconic penguin adorns the New Zealand $5 note and was partly brought to public consciousness via the Mainland Cheese commercials of the late 80s and early 90s. The fourth largest species of penguin in the world, hoiho are the only surviving member of the genus Megadyptes – which means ‘big diver’. This species gets its te reo Māori name hoiho (‘noise shouter’) from their shrill and piercing calls; while ‘yellow-eyed penguin’ refers to their yellow irises. Despite the loudness of their calls during breeding season, hoiho are said to be ‘shy’ and prefer to make their nests away from their neighbours. 

There are two sub-populations of hoiho, known as the northern (mainland South Island, Rakiura and Whenua Hou) and southern (sub-Antarctic Auckland and Campbell Islands) sub-populations. The northern site is the easiest to access for conservationists and has therefore been the most widely studied, and unfortunately this population is in decline. So much so, that it is predicted that this endemic species could become extinct on the New Zealand mainland in the coming decades if the current threats are not reverted.

It is estimated the global population ranges from 2,600-3,000 mature individuals and is undergoing a very rapid decline. In 1999 there were 741 breeding pairs in the northern sub-population, while the total recorded in 2019 was just 265 breeding pairs – a 78% decline in just 20 years!

In 2020 DOC released their hoiho recovery strategy and five-year action plan, in partnership with Te Rūnanga o Ngāi Tahu, the Yellow-eyed Penguin Trust and Fisheries New Zealand. DOC also works with other key partners: the Yellow-eyed Penguin Trust, the Wildlife Hospital Dunedin, Penguin Rescue and Penguin Place to carry out predator control, nest monitoring, disease and injury treatment, starvation interventions and habitat restoration in the penguin’s South Island range.  

There are many threats to hoiho survival – human disturbance, introduced predators like stoats, the availability of food in our ocean and infectious diseases such as avian malaria, respiratory distress syndrome and diphteritic stomatitis (DS), also known as avian diphtheria.

Avian diphtheria is a disease that is so far only known to affect young hoiho. Similar to human diphtheria, this infection causes painful lesions in the mouth that make it difficult to eat and swallow. This can lead to weight loss and starvation, as well as respiratory issues. In severe cases, the lesions become so large and painful that the penguin is unable to close its mouth.

So just how serious is this disease? In 2004, 50% of the chicks in the South Island died from the disease. Hoiho parents produce just two greenish-blue eggs each year, which means every single chick that hatches is precious. To curb their population decline, a bold new strategy was required.

In 2019/20 DOC trialled a new approach where some chicks were uplifted and treated away from the nests, leaving a ‘dummy egg’ in their place so the parents would return. The young chicks were taken to The Wildlife Hospital in Dunedin (a not-for-profit veterinary facility that specialises in the care of New Zealand native wildlife) for treatment. While the majority of these chicks returned to the nest successfully, a few of the older chicks (2+ weeks old) had difficulties staying on the nest once they returned. Responding to this new information, DOC adapted their methods for the 2020/21 breeding season and began uplifting chicks at an earlier age.  

In November 2022, Auckland Zoo bird keepers Sarah Quevit-Perinelle and Suzie Keith travelled to Dunedin to assist in this collaborative conservation mahi. Sarah spent the first week helping DOC staff to monitor and collect sick chicks from nests from the Otago Peninsula breeding colony to be treated at The Wildlife Hospital, with the next two weeks spent at The Wildlife Hospital assisting with the penguin hand rearing and treatment. After the three weeks, Sarah returned to Auckland and Suzie joined this wild work for a further week.

“This is the first year that the chicks were treated at a much younger age, at ‘day zero’ as soon as they hatch. This gives them a much better chance of staying with the parents when they return to the nest and they’re finding this approach is working really well,” explains Sarah.

Our bird keepers have years of experience in bird care, caring for species at the Zoo as well as in the wild. This includes daily husbandry for the Zoo’s colony of little penguin rescues! This valuable experience means our bird team can easily slot into a busy environment and provide their skills and experience. Auckland Zoo vet nurse Breeze Buchanan also volunteered a week of her time to assist the team with preparing medication and meals.

Caring for so many vulnerable hoiho chicks in a busy hospital required a scientific and systematic approach. During this time – two rooms were reserved for penguins (specific room temperatures are required depending on the age of the chicks) and a third room was reserved for treating other wild patients such as gulls. Teams were split into shifts to ensure the chicks were fed 5-6 times per day. The frequency of feeds would depend on the age of the chicks, with younger chicks being fed more often. An incredible 138 penguin chicks were treated over a period of five weeks, with 74 being cared for at one time – that’s a lot of hungry mouths!

Chicks were admitted at 1-3 days old and were returned to the nests at 8-10 days old – so they spent an average of 6-10 days in human care. Not only did the chicks require delicious kai in the form of a fish smoothie (160 litres per day in fact!), but there was also lots of cleaning and prep work to be done - as Suzie explains ‘what goes in must come out!’. This included cleaning and refilling feeding syringes, assisting with feeding, weighing the chicks and maintaining great hygiene standards.

In summation of this busy season, the Wildlife Hospital have called this ‘conservation in action’ as kaimahi from Wellington Zoo and skilled staff from Kākāpō Recovery also joined in this recovery effort.

“I've been involved with Zoo husbandry for 23 years, and over that time, I've spent time out in the field doing different conservation fieldwork. It's really cool to be able to put the skills that you've learned into something and be able to care for the chicks and know they have a really great chance of surviving. It’s hard work, but it’s worth it,“ explains Suzie.  

Of the 138 chicks that were admitted, 95 already had mild cases of diphtheritic stomatitis which proves the benefits of treating chicks at 0-3 days old. Going forward, experts from Otago, Massey and Northumbria Universities are working with DOC into whether it is possible to create a vaccine for avian diphtheria. 

Our staff are passionate about Aotearoa New Zealand’s birds and feel very privileged to lend their skills to this mahi. Currently, Sarah is helping our partners at DOC locate adult penguins from the Otago Peninsula breeding colony that are undergoing their yearly moult. Their aim is to locate all of the penguins while they’re on land, to give them health checks prior to next breeding season. Any penguins that are underweight will be sent to Penguin Place for rehabilitation and sick or injured birds will be taken to the Wildlife Hospital for treatment.

We’ll keep you updated on the outcome of this conservation fieldwork.  

If you’d like to help these beautiful birds, you can do so by:

1. Keeping your distance and leaving the penguins alone.
2. If you see a ‘scruffy’ looking penguin it is likely undergoing a yearly moult – which is completely natural. If you’re unsure please do not approach the penguin, you can call DOC on (0800 DOC HOT).
3. Ensure your dog is on a leash around penguin areas.