New Zealand’s Unique Fauna

New Zealand Fauna

Unique fauna of New Zealand


By: Maria Victoria Gonzaga


In the previous lesson, we learned about the high biodiversity of New Zealand and how geographical isolation led to the country’s high endemism and unique ecosystems. In this lesson, get to know some of the remarkable endemic animals in New Zealand.

Birds

New Zealand has many fascinating birds. Many of them evolved to be flightless and nocturnal. One of them is the kiwi (Apteryx spp.), the country’s most iconic bird. What is fascinating about this bird is that it has its nostrils at the tip of its beak rather than at the top as seen in most birds. Its plumage provides a good camouflage and therefore protects it from its predators. The female kiwi lays the biggest egg, about 20% of the female’s weight. If we are to compare it to humans, it is like a mother giving birth to a four-year-old child. (Ref. 1)

kiwi bird and egg
Left: Kiwi with egg in the Kauri Museum, New Zealand. Credit: Hannes Grobe, CC 2.5. Right: Avian eggs of varying sizes. Credit: Zureks, CC 3.0

Another fascinating bird is the takahē (Porphyrio mantelli), the largest living railbird in the world. It is a conservation icon. It was declared extinct but it was rediscovered. Since then, the species has undergone conservation to revive its population. More details about takahē will be dealt with later on the next tutorial.

takahē
Photo of takahe taken on January 5, 2012. Credit: russellstreet, CC BY-SA 2.0

Whio (Hymenolanimus malacorhynchos), also known as blue duck, is New Zealand’s rarest, endangered endemic ducks in the mainland. (Ref. 2) It has distinctive yellow eyes, a soft bill, a speckled chestnut breast, and dark grey legs and feet. It is a torrent duck capable of living in rivers and streams. The soft bill enables the duck to scrape off the surface of the rocks and feed on invertebrate larvae. (Ref. 3)

Whio
Whio at Staglands in Akatarawa, New Zealand. The photo was taken in July 2007. Credit: Karora

Kererū (Hemiphaga novaeseelandiae) is a bird with blue-green and white plumage. It has the widest gape. Thus, it can eat large berries. Trees, such as karaka, miro, tawa and taraire, rely on this bird species to disperse their seeds. As such, it has been called the “gardeners of the sky” and a keystone species, meaning it is a species on which other species in an ecosystem depend on. (Ref. 4)

kererū
Photo of kererū taken in 2016 (public domain). Credit: Chris B

Bellbirds (Anthornis melanura) and tūī (Prosthermadera novaeseelandiae) are another keystone species. They are important pollinators of Peraxilla spp. (mistletoes). These plants need these birds to pop their flowers open. When these birds feed on the flowers’nectar, they also tweak the flowers of the mistletoes open with their beak. Opening the flowers is important in enabling cross-pollination. (Ref. 5)

 

Bellbird and Tūī
Left: Bellbird photo (Credit: Dave~O, CC 2.0). Right: Tūī photo (Credit: Bernard Spragg). Both birds perched on a mistletoe.

Insects

New Zealand has many remarkable insects. Wētā, for instance, are insects that look like giant crickets. They are flightless and nocturnal. And most of them have ears on their front legs below the knee joint. (Ref. 6)

Giant Weta
A female Cook Strait Giant Weta on Maud Island in the Marlborough Sounds. The photo was taken in 2009. Credit: Mike Locke, CC BY-ND 2.0

Wētā have been in New Zealand for around 190 million years. (Ref.7) They belong to the families Anostostomatidae and Rhaphidophoridae. Five groups of wētā have been described. They are tree wētā, cave wētā, ground wētā, tusked wētā, and giant wētā.

From top left to right: male Wellington tree weta (Credit: Tony Wills, CC BY 2.5), Cave weta – Pachyrhamma edwardsii, male, photographed in Golden Bay, New Zealand (Credit: Mary Morgan-Richards, CC BY-SA 4.0), male Hemiandrus pallitarsis ground wētā at night on shrub leaf (Credit: Steven Trewick, CC BY-SA 4.0), tusked weta Motuweta isolata on Middle Island in the Mercury Islands (Credit: Department of Conservation, CC BY-SA 4.0), and Little Barrier giant weta (Credit:Dinobass, CC BY-SA 4.0).

Tree wētā are found in holes or tunnels (called galleries). When threatened, the lone male in the group defends the gallery against other male wētā by waving its spiky hind legs. The tree wētā males are aggressive defenders. They hiss and bite. (Ref. 6)

Cave wētā have long antennae for navigation. Unlike other wētā, they don’t have ears and therefore cannot hear. They also do not bite, hiss, kick, or scratch. When threatened, they leap away. (Ref.8)

Ground wētā are those found in the soil. Tusked wētā owe their name from the males’ long curved tusks. Females don’t have tusks and look like ground wētā. Males use their tusks for combat and sparring, especially against male competitors. (Ref. 6)

Giant wētā, also called wētā punga – the ‘god of ugly things’, can grow up to 10 cm body length. Its leg spans as wide as 20 cm. Despite their frightening size, they are less aggressive and slower than the tree wētā.

Other remarkable insects are the scale insects, such as Ultracoelostoma assimile and U. brittini. The sooty beech scales are important in forest ecology. They make honeydew, a sweet, sticky droplet. When they extract sap from the tree phloem, they excrete the excess as small droplets. The honeydew serves as an important food source for fungi, insects, and birds. (Ref. 9)

Scale insect honeydew on tree bark
Honeydew scale insects on black beech. Credit: Jon Sullivan, CC-BY-NC-4.0.

Bats

Bats (pekapeka) are the only land mammals native to New Zealand. The paucity of land mammals in the country is largely due to geographical isolation. Only three bat species are endemic — the long-tailed bat, the lesser short-tailed bat, and the greater short-tailed bat. However, Mystacina robusta (greater short-tailed bat) was last sighted in 1967. Thus, it is believed to be extinct. As for the other two bat species, Chalinolobus tuberculatus (long-tailed bat) and Mystacina tuberculata (short-tailed bat), their populations are at risk of vanishing, too. (Ref.10) Recovery efforts are being done to save them from extinction.

Long-tailed bats and short-tailed bats are small. From their nose to their tail, their size is about the length of a human thumb. Their wingspan is about 30 cm and they are expert fliers. (Ref. 11) Most of them are found in the forests, roosting in large hollow trees.

The lesser short-tailed bats are not like most bats that catch prey in the air. They spend most of their time at night ground hunting. They fold their wings and then use their elbows as limbs to forage for food on the forest grounds. Their diet includes insects, nectar, fruit, seeds, and pollen. (Ref. 11)

Endemic bats in New Zealand
From left to right: long-tailed bat, short-tailed bat (Credit: GH Ford – Proceedings of the Zoological Society of London 1857), and the greater short-tailed bat (Credit: Auckland War Memorial Museum – Auckland Museum specimen LM60, CC BY 4.0).

Reptiles

Tuatara, the country’s largest reptile, is the only living representative of Rhynchocephalia — an ancient group of lizard-like reptiles from the Mesozoic. Having traced the lineage of tuatara to this ancient reptile group was an exciting discovery. It is as if we are looking at a species that has persisted over millions of years. Because of this, the tuatara has been regarded by many as “living fossils”. However, this may not be entirely correct. The tuatara may be the last representatives of their ancient group but they evolved and subsequently acquired features that made them distinct from their ancestors. (Ref. 12)

tuatara and relative
On the left is “Henry”, the world’s oldest tuatara in captivity in New Zealand (Sphenodon punctatus) (Credit: KeresH, CC BY 3.0). On the right is a life reconstruction of Priosphenodon avelasi, an extinct relative of tuatara. (Credit:Nobu Tamura, CC BY-SA 4.0)

 

Credit: Dr. Polaris

Frogs

Frogs (Māori names: pepeke, peketua, pepeketua) are the only naturally-occurring amphibians in the country. (Ref. 13) Of the seven native frog species identified, three of them are extinct. The remaining four species are Leiopelma hamiltoni (Hamilton’s frog), Leiopelma pakeka (Maud Island frog), Leiopelma archeyi (Archey’s frog) and Leiopelma hochstetteri (Hochstetter’s frog). (Ref. 13) All species belong to one genus — Leiopelma.

Unlike most frogs, Leiopelma frogs do not croak but they make chirping sounds. Their eyes are round and they didn’t evolve external eardrums. Their tongue is shorter and attached at the back. Thus, they lunge forward when catching prey. And when they hop, they come down in a sort of a belly flop rather than a perfect landing as seen in frogs elsewhere. (Ref.14)

Most of them live and breed on dry land. Unlike most frogs that lay eggs hatching to tadpoles, most Leiopelma frog eggs skip the free-swimming tadpole stage. Instead of hatching from the eggs, the tadpoles develop inside the eggs. And so, when the eggs, froglets, not tadpoles, come out. (Ref. 13)

Leiopelma frog
Hochstetter’s Frog sitting on Moss – Leiopelma hochstetteri

Marine Mammals

Although New Zealand has few mammals on land, it is abundant in marine mammals. Almost half the world’s cetaceans (dolphins, whales, and porpoises) have been sighted in its waters. (Ref.15)

One of its endemic cetaceans is Hector’s dolphins. They include the South Island Hector’s dolphins and the North Island’s Māui dolphins. You can easily identify them from the common dolphins by their round dorsal fin and gray body with black and white markings. They can grow to about 1.5 m in length. Māui dolphins are the world’s smallest dolphins. (Ref.16)

Endemic cetaceans in New Zealand
Left: Hector’s Dolphin (Cephalorhynchus hectori), (Credit: Gregory “Slobirdr” Smith, CC BY-SA 2.0). Right: two Maui’s dolphins (Cephalorhynchus hectori maui) (Credit: Department of Conservation, New Zealand, CC BY-SA 3.0.

Conservation

As already mentioned, there are no native land mammals in New Zealand except for bats. The mammals that are now seen in the country are introduced species. Rats and mice were able to reach and establish on the islands when humans began settling. And as it turned out, many of the introduced mammals became pests. They hunted and disrupted food webs and ecological balance. For instance, wētā have to compete with rats and mice over a similar niche. Both animal groups eat the same things, and yet unlike wētā, rats and mice do not serve as a food source for kiwi or tuatara. (Ref.7)

Many of these fascinating animals are at risk of getting extinct. Thus, conservation efforts are intensified to revive their declining population. In the next tutorial, we will take a closer look at takahē, which was declared extinct but was rediscovered.

References:

1. Conserving our native kiwi. (2019). Science Learning Hub; Science Learning Hub. https://www.sciencelearn.org.nz/resources/2784-conserving-our-native-kiwi
2. Whio – threats and conservation. (2017). Science Learning Hub; Science Learning Hub. https://www.sciencelearn.org.nz/resources/2416-whio-threats-and-conservation
3. Whio – the blue duck. (2017). Science Learning Hub; Science Learning Hub. https://www.sciencelearn.org.nz/resources/2414-whio-the-blue-duck
4. Kererū – our native pigeon. (2017). Science Learning Hub; Science Learning Hub. https://www.sciencelearn.org.nz/resources/2719-kereru-our-native-pigeon
5. Mistletoes and mutualism. (2012). Science Learning Hub; Science Learning Hub. https://www.sciencelearn.org.nz/resources/74-mistletoes-and-mutualism
6. Wētā. (2019). Science Learning Hub; Science Learning Hub. https://www.sciencelearn.org.nz/resources/1962-weta
7. Wētā poo and DNA. (2016). Science Learning Hub; Science Learning Hub. https://www.sciencelearn.org.nz/resources/1963-weta-poo-and-dna
8. Cave wētā. (2018). Science Learning Hub; Science Learning Hub. https://www.sciencelearn.org.nz/resources/2623-cave-weta
9. Honeydew ecosystem. (2020). Science Learning Hub; Science Learning Hub. https://www.sciencelearn.org.nz/resources/1436-honeydew-ecosystem
10. New Zealand bats – pekapeka. (2018). Science Learning Hub; Science Learning Hub. https://www.sciencelearn.org.nz/resources/2837-new-zealand-bats-pekapeka
11. New Zealand Ministry for Culture and Heritage Te Manatu Taonga. (2020). Bats. Govt.Nz. https://doi.org/https://teara.govt.nz/en/bats
12. Tuatara. (2010). Science Learning Hub; Science Learning Hub. https://www.sciencelearn.org.nz/resources/1382-tuatara
13. Native frogs. (2018). Science Learning Hub; Science Learning Hub. https://www.sciencelearn.org.nz/resources/1380-native-frogs
14. Kolbert, E. (2014, December 15). New Zealand’s Crusade Against Mammals. The New Yorker; The New Yorker. https://www.newyorker.com/magazine/2014/12/22/big-kill
15. Marine mammals. (2020). Govt.Nz. https://www.doc.govt.nz/nature/native-animals/marine-mammals/
16. Hector’s dolphin. (2018). Govt.Nz. https://www.doc.govt.nz/nature/native-animals/marine-mammals/dolphins/hectors-dolphin/


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