World Wildlife Day: Big blue whales and little blue penguins/ kororā

Department of Conservation —  03/03/2020

It’s World Wildlife Day and to celebrate the beautiful and diverse species found in the big blue Hauraki Gulf Marine Park, we’re shining the spotlight on two blue species: the pygmy blue whale and the little blue penguin/kororā

Balaenoptera musculus brevicauda vs Eudyptula minor

Let’s compare.

Weight and Length

The adult pygmy blue whale weighs around 90 tonnes (the same as 15 African elephants!) and is approximately 24m in length. The heart of a blue whale is the size of a family car, weighing up to 450 kg, while its aorta (the major blood vessel for the heart) is big enough for a human child to crawl through. We don’t recommend that. 😁

The kororā on the other hand weighs around 1 kg (or two blocks of butter), and stands at a very proud 25 cm. It is the smallest species of penguin ON THE PLANET.

Little blue Penguin.
📷: Auckland Whale and Dolphin Safari


Pygmy blue whales have a light-coloured skin which can appear blue-grey in certain lights. Compared to Antarctic blue whales it has a large head compared to the rest of its body and a shorter tail, giving the whale a tadpole-like shape. Just don’t call it a tadpole to its face.

Blue whale’s blue-grey light-coloured skin.
📷: Auckland Whale and Dolphin Safari

The little blue penguin/kororā wins the true-blue contest with medium to dark blue feathers dorsally (their backs), with white underparts, while the dark feathers on their face extend to just below the eye. The hooked bill is dark grey, the iris blue-grey or hazel, and the legs and feet are off-white with dark soles.

True-blue contest winner!
📷: Shellie Evans

Population and Range

New Zealand is lucky to have its own genetically distinct population of more than 700 pygmy blue whales, while the global population is unknown. Internationally they are only found in the Southern Hemisphere, mainly in the Indian Ocean. Our own population is mostly found off the South Taranaki Bight where there is an abundance of food, but also more recently in the Hauraki Gulf Marine Park.

Kororā were once widespread throughout New Zealand coastlines, but most are now on offshore islands where they are protected from predators and disturbance. They are at risk with a declining population, but are thriving in the Hauraki Gulf Marine Park with its 3,200 kms of coastline (hooray!).  You will often see them in their burrows on Tiritiri Matangi or sometimes in kiwi burrows on Motuihe – space sharers! They don’t move far from home, returning to breed just metres from where they themselves were raised.

📷: Shellie Evans


Pygmy blue whales feed almost exclusively on krill but can also eat plankton which is what they feed on in the Hauraki Gulf. To help them eat krill and plankton they have a series of long pleats under their mouth that close at the belly button, which help the mouth and throat expand when the whale is feeding.

The kororā isn’t as picky, eating a varied diet composed of small shoaling fish, squid and crustacean species.

Dive Behaviour

Pygmy blue whales’ surface 3-5 times over several minutes before undertaking a longer dive for approximately 5 minutes. When they go down for their longer dive, their dorsal fin and tail usually submerge at the same time, and they will sometimes show their flukes (tail). The deepest recorded dive of a pygmy blue whale is 506 metres!

Surfacing blue whale, visible by its blow.
📷: Auckland whale and Dolphin Safari

Kororā live up to their scientific name ‘Eudyptula’, meaning “good little diver”. In ecosystems with plenty of prey, they make short, shallow ‘V-shaped’ dives. If they have to work harder to find food, they make longer, deeper ‘U-shaped’ dives. They can make up to an incredible 98 dives per hour on fish hunting trips, and can dive as deep as 35 metres.

Swim Speed

Not really a fair race…but New Zealand pygmy blue whales have been observed racing at speeds of 33 km/h while little blue penguins more than prove their mettle, using their paddle-like flippers to ‘fly’ through the water at speeds of up to 6 km/h.

Little blue Kororā swimming on the surface.
📷: Auckland Whale and Dolphin Safari


It’s no contest really – it’s unlikely that the little blue penguins’ bark, loud bray ending in an inhalant squeal, or deep growls, will be used to lull humans off to sleep like the majestic low-pitched sounds of the pygmy blue whale.


It is estimated that female pygmy blue whales breed a single offspring once every 2-3 years while fertile, and the average gestation period lasts around 10 – 12 months. The adult female whale will raise her young for up to a year before it is able to survive on its own.

The kororā produces 1-2 eggs per season, incubating them for up to 36 days. Chicks are brooded for 18-38 days and fledge after 7-8 weeks. They are the only species of penguin capable of producing more than one clutch of eggs per breeding season.

Female blue whale swimming with her calf.
📷: Auckland Whale and Dolphin Safari


While rare, ship-strike is a threat to pygmy blue whales.  For example, in 1994, one was carried into the Hauraki Gulf on the bow of a container ship; its bones are now at Te Papa and are one of their most famous display features. The most common threats for pygmy blue whales, and many other whales, are water pollution from oil spills, rubbish, noise pollution from loud jet engines, explosives and boating equipment, and over-fishing which can affect whales living in highly competitive fishing environments.

For our little blue penguin who are used to coming ashore on the mainland, dogs are their greatest threat, as well as cats, ferrets and stoats. These threats have increased with increased coastal development in Tāmaki Makaurau, bringing more dogs and the clearance, or erosion of, traditional nesting sites. They can also be killed crossing coastal roads, get hit by boats, or caught in sea nets.

Arriving ashore to the mainland.
📷: DOC

Sightings in the Hauraki Gulf Marine Park

While the little blue penguin has called the Hauraki Gulf/Tīkapa Moana home for generations, the pygmy blue whale is a more recent visitor – or perhaps returnee – with numbers of sightings increasing year on year.

Historically, it has been uncommon to encounter New Zealand pygmy blue whales in the Hauraki Gulf, but since 2017, sightings of pygmy blue whales have increased, especially in the winter months. Lack of good data makes it hard to know for sure, but the reason could be food as it’s possible that marine heatwaves are changing prey distribution. Or it could just be that their population is gradually recovering from the toll of historic whaling. Wouldn’t that be great?

Auckland Whale and Dolphin Safari taking people out to see blue whales.
📷: Auckland Whale and Dolphin Safari

Kororā are just as evasive as they are nocturnal on land, returning at dusk often in small groups, or “rafts” offshore (teamwork!). Traditional nesting sites include underground burrows, under vegetation, in crevices, between rocks or in caves. Since people came onto the coastal scene, little blue penguins have also taken to nesting under houses and boat sheds, in stormwater pipes, and stacks of timber… or even sushi shops! They are found abundantly throughout islands in the Hauraki Gulf Marine Park.

Nesting among the rocks and caves.
📷: Shellie Evans

How can you help?

Pygmy blue whales:

  • If you sight one while boating follow these guidelines
  • Rubbish can be lethal to whales. Dispose of all your rubbish on land or at sea mindfully – take it home with you!

Little blue penguin/kororā

  • Leave penguins alone. If they look a bit scruffy, they are simply moulting.
  • Keep your dog on a leash on beaches and known penguin areas and warn others nearby of the location.
  • If a kororā tries to nest under your house, block up access points under your house (ensuring that you haven’t blocked on it)
  • Alternatively build a nesting box!
  • Find a local penguin group and donate your time or money. Check out Yellow-eyed Penguin Trust and local Forest & Bird.

Hauraki Gulf Marine Park: New Zealand’s only national park of the sea

The Hauraki Gulf Marine Park/Ko te Pataka kai o Tīkapa Moana Te Moananui ā Toi is New Zealand’s only national park of the seas, covering an enormous 1.2 million hectares and includes six marine reserves.

Cape Rodney Okakari Point Marine Reserve (Goat Island)
📷: Saltwater Eco

The Marine Park is about 20 times the size of Lake Taupō and stretches from Auckland/Tāmaki Makaurau, north above Hauturu/Little Barrier Island, sweeps east to include all Aotea/Great Barrier Island, then tracks south to include all the Coromandel to around Waihi.

It is home to an extraordinary array of marine species – one quarter of all the whale and dolphin species in the world (25 of 88) live in the Hauraki Gulf and more than half visit the area; New Zealand fur seals/kekeno enjoy lounging on the beaches of the many islands (and mainland Auckland), and common dolphins/aihe swim the waters of the Gulf in schools of several thousand. Great white sharks breed in the Gulf and the three biggest fish in the world – the whale shark, the basking shark, and the giant manta ray – are found here; all harmless filter-feeders.

Within the Marine Park are 30 groups of islands and more than 400 individual islets. Of the 93 islands over 5 hectares in size, almost half are free of introduced mammalian predators like rats, stoats, possums, weasels and mice. These predator-free islands are now safe havens for dozens of native forest species including our national icon, kiwi, as well as takahē  kōkako and tieke/saddleback to name a few.  Wētāpunga thrive on Tiritiri Matangi and tuatara live life in the slow lane on Motuihe.  The Marine Park is also considered one of the world’s seabird hotspots with 20% of all seabird species in the world found here. 

Wish the Marine Park happy birthday

The Marine Park celebrates its 20th anniversary in February 2020.  Late summer and autumn are ideal times to enjoy a trip out into the Gulf. You can explore the Gulf from several places – ferry, kayak or private boat. From walks through pest-free island sanctuaries to wine tasting tours, there’s a Gulf trip to suit everyone.

The Hauraki Gulf Marine Park is a national treasure, but it needs care to thrive. If you live near the coast consider getting involved in a beach clean-up or simply reducing your use of plastic. New Zealand is a windy country – lots of plastic rubbish from cities and towns (such as single use straws) ends up blowing into the Gulf, where it can harm or even kill marine animals and sea birds.  The easiest thing to do is if you see any plastic item on land, simply pick it up and put it in the rubbish.

2 responses to World Wildlife Day: Big blue whales and little blue penguins/ kororā


    Thanks for this great article on the Korora! And, happy Wildlife Day to all!


    We where hunting for deer the hut we stayed in was clean and tidy there was firewood. The cupboards were full of non perishable food. We stayed 4 nights. When we left by chopper there was no need to take the food we came with so we left it there also as did others before us we Restocked the fire wood. I would hope the next guests do the same as one day someone who is cold wet and hungry and lost will see this hut and be thankfull and very happy when they see food to cook on the wood stove and warm feet and dry socks.
    Wats up DOC👍👍
    Fellow trampers and hunters that’s how ya do it
    No other place on earth like ours.
    Keep it tidy keep it green