Living World | Subject area | New Zealand Geographic

Living under a rock

It’s been alone for two million years, during which time it lost the ability to fly, and its habitat has shrunk to just a few hundred metres of stream with a view of Dunedin Airport—but the Maungatua stonefly is finally enjoying a moment in the spotlight. Its discovery was an accident: Jon Waters, a professor of zoology at the University of Otago, was out in the Maungatua Range looking for an entirely different species of stonefly. But this species was different, and Waters knew it. It’s flightless, chunky, and short, less than two centimetres long. PhD student Brodie Foster, who led its taxonomic description, called it a “relict”. Juvenile stoneflies, called nymphs, live under stones in rapids. At first, researchers found only nymphs of the Maungatua stonefly, so they reared a male to adulthood to study. DNA analysis confirmed it as a new species, named Zelandoperla maungatuaensis. Landcare Research considers nymphs from the Zelandoperla genus to be indicators of good water quality—they’re among the first species to disappear from an unhealthy stream.

Geo News

Frog apocalypse

Chytrid fungus is the Genghis Khan of the amphibian world: it has spent the past 50 years invading nations one by one, slaughtering as it goes. It has spread to more than 60 countries, wiped out 90 species, and caused significant population declines in more than 500 species, according to an international study led by the Australian National University. The fungus, which eats the skin of amphibians, is responsible for the world’s greatest biodiversity loss due to a disease. Researchers say it should be considered one of the most damaging invasive species in the world—up there with rats and cats in terms of the number of species it endangers. Though chytrid is present in New Zealand and Australia, one nearby land mass remains a sanctuary: New Guinea, which is home to six per cent of the world’s frog species. In June, a team of 30 international experts published a paper in Frontiers in Ecology and the Environment calling for greater support and protection for New Guinea’s island haven.

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Born this way

Three fathers, two mothers, one father and two mothers—all are naturally occuring parent combinations for honeybees. Honeybees are haplodiploid, which means that females hatch from fertilised eggs (and have two parents) while males hatch from unfertilised eggs (and have no father). This makes it possible for new forms of reproduction to occur, and new research into bees’ DNA, published in Biology Letters last November, found that they can have multiple parents of various sexes. Researchers estimate that one to two per cent of bees are born this way—they’re known as sex mosaics, or gynandromorphs, and have a mixture of male and female characteristics.

Geo News

I spy for science

A citizen-science project to spot Otago skinks will help a Dunedin PhD student collect valuable data about the weather conditions that they prefer. Jo Virens set up eight cameras in Redbank Reserve to photograph Otago skink habitat every minute. The result: 750,000 images. Virens now needs help identifying which pictures feature skink appearances. By plotting the reptiles’ activity alongside detailed data on wind, solar radiation, temperature and humidity, Virens will be able to figure out which temperature conditions best suit them. “It’s all about how that affects body temperature, they’re going to be wanting to maintain a body temperature of probably around 25 to 35 degrees.” Then, using localised weather projections for the next 100 years, Virens will be able to create a skink forecast: will there be skink-friendly weather, encouraging them to bask all day long? Or will they need to move to new habitat to survive? There aren’t many skinks to spot—they’re endangered—but they pop into the frame often enough to tempt a viewer to spot just one more. “I’m not expecting it to be that entertaining,” says Virens. “I’m hoping the challenge behind it is what’s going to be appealing about it.” Otago skinks have black and gold markings reminiscent of lichen growing on rock, and reach up to 30 centimetres in length. Their patterns are unique—individual skinks can be identified from pictures of their face markings. Not that they always come that close in Virens’ pictures. Virens has set up the project on citizen-science platform Zooniverse—anyone can view 10 time-lapse images at a time, and flag when Otago skinks appear. Follow this shortcut to access them: nzgeo.com/skink The skinks are hard to spot, warns Virens, so look closely. “The beta test revealed that false negatives—people missing skinks—were relatively common, whereas false positives—people saying they saw a skink when there wasn’t one—practically never happened.”

Geo News

Fossilised fish flock together

Fish have been forming shoals since at least the Eocene Epoch, according to this fossil of 259 tiny, extinct Erismatopterus levatus, which lived about 50 million years ago in giant lakes that covered Wyoming, Colorado and Utah in the United States. By analysing the positions and swimming directions of the fish, researchers from Arizona State University found their group behaviour to be the same as fish species today: they avoid straying too far from the shoal and swimming too close to each other. Communication and behaviour are usually absent from the fossil record, but in this case, a mystery remains: how were these fish preserved mid-swim?

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Goodwill hunting

Spearfishers are taking aim at freshwater pests instead of dwindling marine species.

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The wreck of the penguins

Why did hundreds of dead kororā—little blue penguins—wash up on beaches around the country two summers ago? Has their fate got anything to do with the weather? Or has it got something to do with us?

Geo News

Too much browsing

Is it true that deer act like moa in our forests, filling the ecological niche that moa left empty? Nope, says a new study by Landcare Research–Manaaki Whenua palaeobiologists Janet Wilmshurst and Jamie Wood. They compared prehistoric moa poo with modern-day deer poo, both from Daley’s Flat in the Dart River valley. Using plant pollen preserved in the faeces, they reconstructed the diets of both species, and found a wider variety of pollen in the moa poo. This points to a more diverse forest having existed at the time. Some of the plants found in moa poo are now restricted to areas deer can’t reach. (The lower half of the picture above is a boulder-top inaccessible to deer.) “It is the final nail in the coffin for any idea that deer fill the same job vacancy in the ecosystem as moa,” says Nic Rawlence, director of the University of Otago’s palaeogenetics laboratory. “Ever wondered why our native forests are relatively open under the canopy? Now you know why.”

Geo News

Bat maps

The lesser short-tailed bat was once in residence in forests around the country, but has disappeared since the arrival of humans, thanks to forest clearance and the introduction of predators. Short-tailed bats are thought to be important pollinators—they crawl on the forest floor to forage for food.

Geo News

New squid on the block

A number of squid newcomers have been found on a single research expedition to the Kermadecs, an island arc 1000 kilometres northeast of New Zealand. AUT University postdoctoral research fellow Heather Braid defrosted about 150 cephalopod specimens collected in late 2016 on a NIWA deep-sea survey voyage, identifying 43 species. Thirteen of these had not been sighted in New Zealand waters before, including bobtail squids, comb-fin squids and myopsid squids. Five are likely new to science (three of the five are pictured below; the other squid, lower right, is Histioteuthis miranda). Braid extracted DNA from the new species in order to compare them with squids from other parts of the world. [gallery columns="2" link="none" ids="329323,329324,329325,329326"] The Kermadecs are a site of high marine biodiversity, thanks to the juncture of a warm ocean current from the north and a cool current from the south. There is a long-stalled campaign to declare a marine sanctuary across the region. “Pretty much every time they go they find something exciting,” says Braid. “We have one of the highest biodiversities of squid and octopus species in the world.”

Geo News

Slender button daisy

Leptinella filiformis

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Where are all the spotted shags?

Seabird scientists are creating a fake home for shags on the Noises, an island group off the coast of Auckland, in the hope that the Hauraki Gulf’s rapidly diminishing spotted shag population will be fooled into thinking it’s a great place to start a family.

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Bat signals

Nightfall, and the forest comes alive with squeaking. Or it used to. Lesser short-tailed bats are clinging on in a handful of places, their populations blinking out of existence. Yet researchers are only just beginning to learn about our bat species—New Zealand’s only native mammals—and what they’re finding out is pretty weird.

Geo News

Insectpocalypse now

The first global review of studies about the decline of insects predicts the planet will lose its insects within a century if the current rates of extinction continue. Notable insect population crashes have been documented in Puerto Rico, where one study found a 98 per cent decrease in ground insects over 35 years, and the United Kingdom, where butterfly species dropped by 58 per cent in a decade on agricultural land. In Oklahoma, only half of bee species recorded in 1949 were found in 2013, while in Germany, the abundance of flying insects in national parks declined by 75 per cent over 25 years. Insects are the most abundant animals on Earth—they outweigh humans by 17 times—but their mass has been declining by 2.5 per cent a year for the past three decades. The insect rate of extinction is eight times higher than that of birds, mammals and reptiles. According to the analysis, which will be published in Biological Conservation in April, the decline in insect numbers is primarily due to intensive agriculture, heavy pesticide use, loss of habitat through urbanisation and climate change. “Unless we change our ways of producing food, insects as a whole will go down the path of extinction in a few decades,” write the authors of the review. “The repercussions this will have for the planet’s ecosystems are catastrophic, to say the least.”

Geo News

Moth magnet

On spring nights, bogong moths migrate to the Australian Alps, travelling distances of more than 1000 kilometres to reach the cool mountain caves where they spend their summers aestivating. But how does the moth navigate from its winter breeding grounds to the alps? Tests in a flight simulator found moths found their way by the stars and moon, but became disoriented when researchers deliberately misaligned the sky and the Earth’s magnetic field. That magnetic field is crucial to the moths’ ability to find their way, making bogong moths the first nocturnal insect known to use magnetic sensitivity as a tool in long-distance migration. (Birds have long been known to navigate using the Earth’s magnetic field.) Do other insects have an internal compass tuned to the Earth’s magnetic field? Study co-author Eric Warrant, a sensory physiologist from Lund University in Sweden, says monarch butterflies, which migrate by day across the United States to overwinter in Mexico, may also have some magnetic sensitivity, but their primary compass is the sun: “Bogong moths must rely on the Earth’s magnetic field because the moon is a very variable and unreliable cue compared to the sun—which is a very constant cue day after day.”

Geo News

Safety in flamboyance

Birds with colourful plumage are better at attracting mates, but also more likely to attract predators—right? Well, no. When a team of New Zealand and Australian biologists investigated whether dull-coloured birds had better survival rates than brightly coloured ones, they found both were equally likely to be attacked. The fairy-wren, an Australian songbird, varies wildly in colour—some have brilliant plumage, while others are nondescript. The researchers placed 3D-printed models of the birds at eight fairy-wren sites in Australia, then settled in to watch. They found that 13.1 per cent of brightly coloured female birds were attacked, compared to 13.6 per cent of dull-coloured females. But there was a wide discrepancy in the rate of attacks between sites, suggesting that survival had more to do with vegetation and location than the flashiness of the birds’ feathers. “While being brightly coloured can be important, for example in competing for a mate, the assumption has been that it is costly for birds because it appears to scream ‘Here I am, come eat me’,” says lead researcher Kristal Cain of the University of Auckland. “It suggests the relationship between predation and colour is not as simple as we might have thought. “Instead, it appears that because males and females behave differently—females often take more risks—bright feathers may be more dangerous for females than for males.”

Geo News

On the spectrum

Birds fly at high speed through dense forests without crashing into trees or leaves—and this navigational prowess may be due to their ability to see ultraviolet light. Two researchers photographed forest habitats with a multispectral camera, allowing them to look at the scenes through the birds’ eyes. In a paper published in Nature Communications in January, they determined that contrast between leaf surfaces was greater with UV vision, and speculated that UV vision also helps birds search for particular leaf surfaces, leading them to prey or safe refuge.

Geo News

Why don’t birds have teeth?

Birds may have lost their teeth to speed up hatching time, according to a new theory published in May in Biology Letters. The toothless beak is a relatively recent invention. Dinosaur birds had teeth, and incubated their eggs for a lengthy three to six months. Research on fossil embryos shows tooth formation took 60 per cent of this time. But eggs in open nests are vulnerable to predation, compared with mammal embryos that are protected inside the womb, or eggs that are buried. Losing teeth would allow for a shorter incubation time—and thus a higher survival rate for chicks. Other theories postulate that birds lost their teeth in order to become light enough to fly, and that the toothless beak is better adapted to certain foods.

Geo News

Taking calls

A happy hihi, or stitchbird, has a call that sounds like two marbles clacking together. Using sound-recording devices, researchers listened to hihi calls in Rotokare Scenic Reserve in Taranaki to determine whether the reintroduction of the birds to the area was successful. “By recording and listening to the hihi calls, we were able to figure out how the birds were using the area they’d been reintroduced to,” says PhD candidate Oliver Metcalf, from a Zoological Society of London research team. “Using the calls, we found the birds moved from an initial exploration phase around the habitat, to a settlement phase—meaning the birds had established their own territories.” It’s hoped that auditory monitoring may replace more-invasive radio tracking for some species. Since 2004, six new populations of hihi have been established across their former range.

Features

Road to recovery

Takahē numbers are rising by 10 per cent a year. The problem now is where to put them.

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