Niche shifts and biodiversity

[[☃ image 1]]

Welcome to lesson 2 of this unit!

In the last lesson we looked at the geological and tectonic forces that shaped this whenua (land). These forces didn’t *just* affect the land though, but had a profound impact on the plants, animals and insects that populate New Zealand. So profound that it has been compared to studying life on a different planet. We will look at what is meant by this to appreciate just how amazing Aotearoa and its furred, feathered and scaled inhabitants are.

While there is a huge amount of unique diversity in Aotearoa's flora and fauna, we will focus mostly on some of our most unique bird life as well as a few other special creatures.

####What do you know about the wildlife in Aotearoa New Zealand? Perhaps you've heard of the flightless kiwi... but do you know of any of our other native animals? Share anything you know down below!

[[☃ image 7]]

##Alien Islands

So now that we understand the ways in which the whenua (land) of Aotearoa New Zealand has changed over the 85 million years since its separation from Gondwanaland, it’s time to consider how that has contributed to creating its biodiversity. It is a biodiversity that Pulitzer Prize-winning science author Jared Diamond describes as:

"The nearest approach to life on another planet.”

The primary reason for this is simple – the animal life that evolved in New Zealand did so without the presence of mammals. The separation of Zealandia from Gondwanaland almost certainly contributed to our once mammal-free status, but explanations for why that is vary, due in part to a lack of fossil evidence. What is clear is that unlike every other continent on Earth, mammals never gained an evolutionary foothold here (with one - quite literally- tiny exception).

It may be that they just never became firmly established on the part of Gondwanaland that broke off, or that any that did were outcompeted by other life. Perhaps they met the same destruction by asteroid that our dinosaur-like animals did, or maybe they drowned when early Zealandia was submerged into the sea before rising anew. That story is still being discovered.

Regardless, having become dominant species elsewhere and heavily impacting the evolution of all other species around them, their absence has led to a huge variety of species in New Zealand that look and behave nothing like their cousins elsewhere.

##Niche Shifts

We can see this starkly in a phenomenon called “Niche shift”. An ecological niche is the role a species plays in an ecosystem, its position on the food chain, and how it ensures it is not in direct competition with another species with which it competes for resources. It encompasses things like what it eats, what it is eaten by, where it lives, and the times of day it is active.

Elsewhere of course, many of these ‘niches’ are occupied by mammals, and typically the same kind of animal occupies the same niche in countries all over the world. In Aotearoa that is turned on its head and a ‘niche shift’ has occurred where they are occupied by creatures that one might not expect.

Examples of this include:

• Giant wētā fill, in many ways, the niche usually held by rodents. (check out this short video on wētāpunga from Auckland Zoo!)
• Kiwi, nocturnal ground foragers who sleep in burrows, are filling a niche more often occupied by mammals such as hedgehogs.
• Moa, an extinct giant of a flightless bird, filled the ‘grazer’ niche that might elsewhere have been filled by deer, buffalo alpaca, or even kangaroos.

[[☃ image 1]]

##Mountain Dwellers

Another consequence of the geological history of New Zealand is the presence of the only alpine cicada (surprisingly hairy), alpine gecko (reclusive and mysterious) and alpine parrot (the notoriously clever and mischievous Kea) in the world.

As the mountains of the Southern Alps rose around 5 million years ago, they presented an uninhabited niche for these species to inhabit as they rapidly evolved alpine-specific traits with little competition. It has been estimated that evolution in response to the rising of the Southern Alps is responsible for the existence of one third of New Zealand’s endemic (native) species.

[[☃ image 2]]

Not all of New Zealand’s alpine species had such rapid evolution however. The tiny Rock wren, our smallest bird, who lives nestled among the rocks under layers of snow, hitched a ride from Gondwanaland and is the closest living relative of the earliest primitive songbirds.

[[☃ image 3]]

##The Loneliest Reptile

Enough about birds for now, because Aotearoa is also home to one of the most interesting lizards in the world… almost. While the Tuatara may look like a lizard, it’s not. In fact it has no living relatives even remotely like it anywhere in the world. To put into perspective just how unique this little guy is, the entire world of reptiles can be divided into snakes, lizards, turtles, crocodiles… and the tuatara.

Back when the Earth was ruled by dinosaurs, tuatara-like animals were widespread. While the tuatara managed to survive what the dinosaurs did not, the rise of the mammals wiped them out everywhere. Everywhere, that is, except for New Zealand.

They're often referred to as "living fossils", and can live for up to 100 years. Read more here about the many traits that make tuatara so unique - including their 'third eye'!

They’re not our only weird reptile though. We also have our geckos, almost all of which don’t lay eggs like most of the rest of the world’s geckos, but give birth to fully formed young.

Amphibian-wise, there’s also our strange frogs, who exhibit the opposite behaviour. Rather than their offspring having a free-swimming tadpole stage, this stage is accommodated within very large eggs, guarded by the father. Upon hatching, they climb aboard his back, allowing him to raise them hidden away in the forest away from the water and hopefully, predation.

[[☃ image 4]]

##Batty Behaviour

Lastly, the mammal exception. New Zealand is home to two native species of ‘land’ mammal - the long and short tailed bats. But even these are unique in the world of bats, particularly the smaller of the two, the pekapeka.

Bats the world over hunt on the wing, never setting foot on the ground. Pekapeka however - almost certainly due to the absence of ground-dwelling mammalian predators - has strong back legs and wings that can close completely, allowing it to scurry along the forest floor, rooting through the leaf litter for its meals. No other bat in the world does this. Pekapeka is also a more varied eater than most bats, eating not just insects, but fruits, nectar and pollens.

[[☃ image 5]]

###What have you learned so far? Share a list of 2-3 key points in the discussion below. Has anyone else shared similar points?

####References:

Diamond, J.M. ‘New Zealand as an archipelago: An International Perspective’ in Ecological Restoration of New Zealand Islands, Conservation Sciences Publications, No. 2, Department Of Conservation, Auckland, 1990, Pp. 3-8

Gibbs, G. ‘Ghosts of Gondwana: the History of Life in New Zealand’, Craig Potton Publishing (now Potton & Burton), Nelson, 2011
Truly, an astonishing work that with both clarity and depth reveals the incredibly unique and marvellous nature of life in New Zealand. If this topic is interesting to you, find his book here.

[[☃ image 1]]

##What if

According to internationally acclaimed natural scientist Tim Flannery, New Zealand is:

“A completely different experiment in evolution to the rest of the world. It shows us what the world might have looked like if mammals… had become extinct 65 million years ago, leaving the birds to inherit the globe.”

There are many fascinating products of this ‘experiment’, but let's look at just a small selection of the weird, wonderful, and terrifying biodiversity that New Zealand's land of birds has generated.

##Strange & Stinky

To understand what makes New Zealand birds so different, it helps to understand some of the basics of birds everywhere else. Let’s think of a cat as an example predator. It’s fast, often hunts under cover of darkness, has a strong sense of smell and hearing, and vision that is poor at perceiving colour. So birds that evolved with predators like cats are active during the day, fly away at the smallest threat, and frequently attract their mates with bright colours that their predators can’t perceive.

New Zealand birds like the kākāpō, the world's lone flightless parrot, evolved to survive in the face of a completely different type of predator - other birds, like hawks and eagles who hunt in the day. These predators hunt on the wing, and depend on sharp vision to hunt, not scent.

Because of this, kākāpō evolved to freeze, not flee, in the face of danger. Their drab colour allows them to camouflage themselves from these aerial predators, essentially disappearing into the background of native bush when they freeze. They also evolved to become nocturnal - another aberration in the parrot world. Like many native birds in Aotearoa New Zealand, kākāpō sacrificed colour for scent to find each other in the wild, releasing strong smelling oils into their feathers.

This trait of New Zealand birds to have strong odours is so unique to Aotearoa New Zealand, that part of the experience visiting the Te Taiao | Nature zone at Te Papa Tongarewa is the opportunity to experience those scents yourself.

[[☃ image 2]]

##Giants

Life on the ground has also led to the kākāpō to becoming the world's heaviest parrot but here, that's not so unusual. While not unique to New Zealand, the phenomenon of island creatures evolving to become giants compared to their landlocked brethren has lead to a few notable behemoths in New Zealand's feathered inhabitants. These include:

• The mighty moa. A flightless herbivore, moa were huge birds with appetites to match. They filled the niche of grazer, like the four-legged herbivores deer or cattle in other countries. Though now extinct, there were once nine or more species of moa in New Zealand, ranging from the big (20kg) to the massive (250kg & 2m tall). Like the lonesome tuatara, they were a primitive and unique species, with no living relatives of their order left anywhere on earth.

• As big as the moa was, it’s an alarming thought to know that there was once an eagle big enough to prey on them. Haast’s Eagle was the largest eagle in the world with a wingspan up to 2.6m. It is believed they were of a size and strength to hunt humans. No fossil evidence of this has been found, but Māori mythology speaks of a terrible and fearsome bird known as Pouakai, Hokioi or Hakawai that many believe to have been the Haast’s Eagle.

• Though not birds, honourable mentions include the wētāpunga, one of the worlds largest insects, and our giant (and carnivorous) kauri snails (pupurangi).

[[☃ image 3]]

##Moa Food

Even the plants of Aotearoa New Zealand bow to the dominance of her birds. While many birds and native plants have co-evolved to benefit each other (for example the Tūi beak shape has co-evolved with the shape of native harakeke, kowhai, and kaka beak flowers), two native plants in New Zealand have developed astonishing adaptations to protect themselves from the voracious appetite of the Moa.

###Divarication

According to some biologists, this unassuming bush is actually an example of an ingenious solution to the problem of being eaten by moa. The tangled look of its branches is due to a trait called divarication, marked by small leaves, and wiry stems that branch off from each other at wide angles- resulting in a solid, spiky, tangled little bush.

The trait is found in a much higher proportion in New Zealand than in other countries, perhaps due to the strong evolutionary pressure of the moa. The theory posits that the spring-like nature of the stems and the tiny leaves made grazing on these bushes too costly in terms of energy to moa to be an appetizing food source.

[[☃ image 4]]

###Lancewood

The lancewood is another native plant that appears to have evolved drastic defences against being eaten by moa. In its mature form, once it grows taller than the average moa, the lancewood is an unremarkable tree, with a tall straight trunk branching out into regular green leaves only at the top. But in its juvenile form, under around 3m, it looks very different. In this form it has long, tough, serrated saw-like leaves - far more difficult and energetically costly for the moa to graze on.

[[☃ image 5]]

##Creatures of the night

No discussion about unique New Zealand creatures would be complete without mentioning our beloved and iconic kiwi. The kiwi has so adapted to occupying a niche usually belonging to nocturnal ground mammals that it has several most unbirdlike features.

[[☃ image 6]]

Its feathers are so loose and downy they're almost like hair. It has marrow-filled bones (not hollow like other birds), whiskers, no tail, and only small vestigial wings. It does not rely on vision but, like many mammals, on hearing and a strong sense of smell. It uses this when poking its long beak deep into the earth to sniff out earthworms. This is helped by having nostrils at the tip of its beak - like no other bird on Earth!

Kiwi also lay huge eggs – six times bigger than normal for a bird that size!
That means when pīpī (chicks) hatch, they’re fully feathered and ready to run.

[[☃ image 7]]

####Further Reading:

The Kākāpō, from New Zealand’s Department of Coservation

Making the Haast’s eagle model at Te Papa for the Te Taiao | Nature, 2019 exhibition

Behind the scenes of assembling the Moa skeletons at Te Papa for the Te Taiao | Nature, 2019 exhibition

Ghosts of Gondwana by George Gibbs

###Is there anything you're unsure of or would like to know more about? Your fellow learners might be able to help! Ask a question in the comments below. Help others by reading and responding to their questions if you can.

[[☃ image 2]]

That was a lot of information! Hopefully it has given you an appreciation for why Aotearoa New Zealand’s biodiversity has such a treasured status, and why it is a prominent part of our national museum.

Te Papa Tongarewa is not a stuffy museum of old, these exhibitions are designed to engage curiosity and the senses. Interactive displays are everywhere, encouraging you to ask questions.

You can smell our birds at the scent bar, and in Te Kōhanga \| 'The Nest' - a giant tightly woven basket in the centre of the room- you can immerse yourself in the calls of dozens of our songbirds. The exhibition closes on a call to action. The millions of years long grand experiment is in crisis. In the next section we will look to the future of New Zealand’s biodiversity, and the role Te Papa plays in protecting it.

####Now that you understand its importance, this video is your opportunity to tour the *Te Taiao \| Nature* & *Whakarūaumoko \| Active Land* exhibitions of Te Papa Tongarewa and see the immersive way this matauranga (knowledge) is passed on to our visitors.

[[☃ video 1]]

####Further Resources

[Contribute to The Current \| Te au interactive exhibit in the Te Taiao \| Nature zone at Te Papa. Add your voice to The Current and help solve New Zealand’s toughest nature challenges.](https://www.tepapa.govt.nz/discover-collections/read-watch-play/science/current) [Learn te reo with a tour of Te Taiao \| Nature](https://www.youtube.com/watch?v=0jF8hKo_6Fg&list=WL&index=32)

###After the last few steps, we'd love you to take a moment to pause and reflect on your learning experience so far. Share any thoughts you have below.

[[☃ image 1]]

**We’ve covered a lot in this lesson!**

We've learned how the unique geographical history of the Zealandia continent created evolutionary pathways unlike anywhere else on earth.

We saw how the absence of mammals impacted the way our birds, insects, and reptiles evolved, and how that led to niche shifts — where our birds and insects behave almost like mammals do elsewhere in the world.

We also met some of our weirdest and most treasured species, and saw how this alien world even led to unique plant evolutions.

Finally, we saw a brief insight into how the national museum tells it's visitors about this incredible story.

We’ll see you in the next lesson to learn what happened to all these incredible animals once humans got to these untouched shores, and how we work to protect them today.

###What did you learn in this lesson that you found the most interesting? Why?

**Post your comment, and react or respond to someone else.**