UNCW researcher finds evidence of past penguin supercolony

Adélie penguins nest on the lower terrace of Cape Adare in the Ross Sea region of Antarctica. During a research trip in mid-January, UNCW biology and marine biology professor Steven Emslie said evidence found suggests around 2,000 years ago the area may have been the nesting ground for a "supercolony" of nearly 1 million Adélie penguins. Photo contributed by Steven Emslie.

 

By Hannah DelaCourt
StarNews Staff

Published: Sunday, February 28, 2016

WILMINGTON -- For more than two decades, University of North Carolina Wilmington biology and marine biology professor Steven Emslie has traveled to Antarctica to study Adélie penguins.

During his most recent research trip from December to January to Cape Adare in the northern Ross Sea, Emslie found evidence that an Adélie colony that breeds on a lower terrace in the region may have once been double in size.

The colony on Cape Adare today is the largest Adélie penguin colony in Antarctica, he said, with more than 338,000 nests of breeding pairs.

Because of past research trips, Emslie said he knew abandoned penguin colonies were along an upper terrace above where the birds breed today, but he did not know the scale of them until this season.
“I was probing the ground, and I would see the eggshell remains that indicated former nests there,” he said. “It just kept going on and on and I just couldn’t believe it. We walked a kilometer from the terrace where penguins can gain access to the top and we were still finding abandoned sites.”

Emslie said this evidence means once the lower beach had filled in and penguins had covered that with their nests, more penguins coming in would climb 300 meters up a cliff and then walk up to a kilometer farther to get a nest site.

“I’ve never seen anything like that,” he said.

The two-month research trip stems from collaborative research conducted by UNCW, Louisiana State University and the University of California at Santa Cruz using grants from the National Science Foundation totaling nearly $1.28 million.

Emslie's research partner at LSU, Michael Polito, an assistant professor of oceanography and coastal sciences and principal investigator for the overall project, received his undergraduate and Ph.D degrees from UNCW. Ashley McKenzie, a UNCW graduate student, also helped collect samples on the trip.

With the discovery, Emslie estimates the former “supercolony,” as he calls it, would have comprised of more than half a million nests, or a million birds, when a major population shift occurred nearly 2,000 years ago.

Using sediment and other data samples collected during their trip, Emslie said the next steps will be to complete stable isotope and radiocarbon dating analyses to try and determine if there was a dietary shift going on at the time that would account for such a large colony to amass at the location.

And he hopes to also find answers as to why the area was later abandoned.

Just because the area was abandoned does not mean the number of Adélie penguins is dwindling. He said the birds may have had to move somewhere else to nest because of changes in the environment such as sea ice blockage or icebergs changing the currents.

The data and any answers found, he said, could help direct further research into the current colonies in Antarctica.

"If we can understand what happened in the past with population shifts and dietary changes it can help us understand and predict what will happen in the future with current warming trends and changes in ocean environments and how that’s impacting penguins today," Emslie said. "(Penguins) are really a bioindicator species for the marine environment because they feed on krill and any changes in krill is due to changes in algae, and that’s due to sea ice so there is a linkage between the physical and biological environments."

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Penguin feathers’ ice-resistant design revealed

24 February 2016

By Emma Stoye

© Shutterstock

The structural features that prevent ice forming on penguins’ feathers have been copied to make an ice-resistant polymer surface. The team behind the work says the surface could help to design new freeze-resistant coatings, and might one day lead to a coating to protect ships and aeroplanes from deadly ice storms.

In recent years much effort has gone into developing superhydrophobic surfaces that repel water, using ridges or bumps to create unevenness that prevents water settling. But at low temperatures, these are vulnerable to becoming coated with ice if ice crystals form in the gaps between ridges, or water droplets coalesce and freeze.

Some hydrophobic surfaces take their designs from nature, such as the leaves of slippery plants or the namib desert beetle, and in this case researchers turned to penguins – who can walk and swim in sub-zero temperatures without their feathers frosting over – for inspiration.

They collected some shed Humboldt penguin feathers from a zoo in Beijing and looked at them under a scanning electron microscope. They identified several air-trapping structures including nanoscale ridges and interlocking hooks on the barbs of the feathers that would create the characteristic rough surface needed for superhydrophobicity. When they sprayed them with supercooled water microdroplets they found that as well as being very good at repelling water, the feathers stopped ice forming. ‘We believe that the nano-grooves on the feather and the microscale distances between the adjacent feathers are crucial to the icephobicity,’ says team member Jingming Wang from Beihang University. The group observed that neither water droplets nor ice crystals were able to stick to the feathers well.

Under the microscope, the polyimide replica feather (top) has a radial density distribution (bottom) similar to a real penguin feather © American Chemical Society

The next step was to try and replicate these ice-resistant properties on an artificial surface. The team used high pressure electrospinning to build a fan-shaped replica ‘feather’ using very thin polyimide fibres. ‘The structure of the penguin feather is too complicated to replicate completely,’ says Wang. ‘We chose to focus on the main structure of the nanoscale fibres and the microscale distances [between them].’

When they carried out similar tests on the polyimide surface, they found that it was less icephobic than actual feathers. But the icephobicity could be altered by adjusting the spacing between the fibres. ‘If the distance between the air-infused nanostructures is high enough, the adhesion force between the ice and ice-resistant surfaces can be reduced, [and] the replica achieves good icephobicity,’ says Wang. When the spaces between the fibres were greater than the diameter of the droplets the surface could be sprayed with supercooled water at -5°C for hours without any ice forming.

The team hope their observations could be useful for designing new materials that are resistant to ice, such as the insulators used for electric cables.

Neil Shirtcliffe, who works on superhydrophobic surfaces at Rhine-Waal University of Applied Sciences in Germany says the findings are interesting because there has been ‘surprisingly little’ work on penguin feathers and ice. ‘The conclusions seem to agree with many others, that ice-resistant surfaces can be produced using roughness, but that more is needed than for superhydrophobicity,’ he comments. ‘We have many ways of producing and arranging polymer fibres, so this could help reduce the cost of ice-resistant coatings,’ he says, adding that the feather-inspired design would probably have to be further optimised, as ‘penguins have different environmental demands than a typical icing storm that might hit an aeroplane or bridge’.

References

S Wang et al, J. Phys. Chem. C, 2016, DOI: 10.1021/acs.jpcc.5b12298

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WATCH: A Detroit Zoological Society expedition to Antarctica

Feb 19, 2016

The Detroit Zoological Society (DZS) posted some footage of their donor-funded expedition to Antarctica. They uploaded some of the footage to Facebook, but have yet to go through all the footage they took.

DZS CEO Ron Kagan was on board the ship. As well as world-renowned polar ecologist and penguin expert Dr. Bill Fraser, head of the Polar Oceans Research Group. 30 donors and DZS board members joined them, and DZS staff members took part in the expedition.

The staff members objectives included “filming for the Science On a Sphere network, creating educational video and content for the Polk Penguin Conservation Center, using infrared thermography in animal welfare research, and identifying new field sites for research which the National Science Foundation funds.” According to Jennie Miller of the DZS.

While there they retrieved one of their life sciences staff members. The staff member had been there for the last three months assisting with penguin research.

The video was posted to Facebook February 17th, and has over 7,000 views. It has been shared over 70 times.

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Clues to Penguins’ Response to Climate Change May Be Uncovered in Recently Discovered Abandoned ‘Supercolony

02/16/2016

More than 600,000 Adelie penguins nest on Cape Adare, Antarctica.Steve Emslie, UNCW

BATON ROUGE – Researchers recently discovered that Antarctica’s most populous colony of Adélie penguins may have once been nearly twice the size it is today. Clues about why the colony grew so large and what caused the population to decline could help scientists chart the penguins’ response to changes in climate and food resources.

Collaborative research conducted by LSU, University of North Carolina Wilmington, University of California at Santa Cruz and University of Saskatchewan led to this discovery at Cape Adare, Antarctica.

“The goal of this multi-institutional collaborative project is to use penguins as sensitive indicators of past changes in the Antarctic marine environment,” said LSU Assistant Professor Michael Polito, the principal investigator of the project. "Samples from this newly discovered ancient colony at Cape Adare will allow us to track the penguins’ diets and population movements relative to natural and human-induced shifts in climate and food availability.”

Last month, a research team led by UNCW Professor Steve Emslie visited the large breeding colony of Adélie penguins at Cape Adare in the northern Ross Sea, which currently has more than 338,000 breeding pairs in one area.

During this visit, they found an abandoned “supercolony” on an upper ridge, which the researchers estimate was populated by more than 500,000 breeding pairs or more than 1 million penguins based on the total area of the abandoned nesting sites.

About 2,000 years ago there may have been a large influx of penguins to the colony at Cape Adare as climate shifted causing ice to block access to other nesting colonies farther south along the Antarctic continent, the researchers theorize. As the Cape Adare colony grew, the nesting grounds expanded to the upper ridge. However, a supercolony can thrive only as long as rich food resources are available.
“Many seabirds have large breeding colonies today that are located near abundant food resources,” Emslie said. “Most of those colonies are in decline, though, due to changing ocean temperatures and other factors that impact those food resources.”

The researchers will use radiocarbon dating to pinpoint the age of the abandoned nesting sites and stable isotope analysis of the colony’s ancient penguin feathers and eggshells to determine what the penguins’ diets were at the time the supercolony was active. This will lead to further clues as to when and why the Cape Adare colony shrunk to its current size.

“Understanding the past diets and population movements of penguins will help us better understand how these predators, and the Antarctic marine ecosystem as a whole, will respond to current challenges such as global climate change and expanding commercial fisheries,” Polito said.
This research is supported by the National Science Foundation.

Michael Polito is an assistant professor in the Department of Oceanography & Coastal Sciences. He is available for interviews. LSU has a video uplink studio with live broadcast capabilities.

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Chubby king penguins wobble when they waddle

Science Ticker

by Helen Thompson

February 17, 2016

When king penguins put on weight, it changes their waddling posture and causes them to walk less steadily (right) than when they are thinner (left), a new study suggests. Given that previous work has suggested that fat penguins expend the same amount of energy as thin penguins when walking, it’s unclear what the metabolic cost of this wobbling might be. 

Astrid Willener

King penguins excel at swimming. With such short legs, walking is not their forte and drains a lot of energy. Yet, every summer king penguins come ashore and trek inland to breed. They can’t forage during that time, so they pack on the pounds before coming ashore and then fast while on land.
To determine how the extra weight affects a penguin’s waddle, biologist Astrid Willener and her colleagues captured 10 wild male king penguins as they came ashore on Possession Island, between Madagascar and Antarctica. Special monitors called accelerometers measured aspects of the penguins’ gait while the animals walked on treadmills before and after a fasting period.

Fat birds were less steady on their feet than thin birds, the team reports February 17 in PLOS ONE. King penguins carry this weight on their front, which likely shifts their center of gravity and results in a less stable posture.

Penguins that are too wobbly could be vulnerable. If king penguins can't stand up and walk, they will be spotted by their predators such as giant petrels and eaten, says Willener. “So it is a huge matter for them to be able to still walk steady while being ‘fat’.”



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Penguin Apocalypse: Adelie colony in Antarctica faces extinction as giant iceberg blocks sea (VIDEO)

Published time: 11 Feb, 2016 

© Intrepid Science / YouTube 

A massive nature drama involving some 10,000 Adélie penguins and an iceberg is playing out in an Antarctic bay opposite Australia. Scientists fear the colossal ice heap is blocking the birds from feeding in the sea, and they have already stopped hatching.

The iceberg named B09B, which hit the Commonwealth Bay in 2011, is the size of a small country. It has cut off the birds’ food supply and altered their environment. While the unfolding events sound like a plot right out of the animated movie Happy Feet, it took scientists several years of serious research to realize how grave the penguins’ situation really is.

Researchers from the University of New South Wales censused the penguins as part of the Australasian Antarctic Expedition 2013–14 and have now published their findings in The impact of the giant iceberg B09B on population size and breeding success of Adélie penguins in Commonwealth Bay, Antarctica in Antarctic Science.



They found that the sea ice extended up to 60 kilometers across East Antarctica's Commonwealth Bay in 2013 and the penguin colony at Cape Denison now has a 120-kilometer journey to feed at the sea ice edge, leaving a devastating impact on the population.

About a century ago, it was estimated that around 100,000 penguins made their base at Cape Denison.

There are now less than 10,000 left, according to the research team, which also noted the remaining penguins were docile and that many were not hatching eggs.

The researchers found, however, that an Adélie population “on the eastern fringe of Commonwealth Bay, just 8 km, from the fast ice edge was thriving, indicating the arrival of B09B and fast ice expansion” were the probable factors behind the population decline at Cape Denison.

They also noted hundreds of abandoned eggs and “freeze-dried carcasses of the previous season’s chicks” on the ground.

Professor Chris Turney of the University of New South Wales, one of the report’s authors, told IFL Science: “We have no idea how long B09B will stay there. It could move this year, or it could be there for decades to centuries.”

"There is some evidence that this might have happened in the past," Turney added.

It is not known how the 5,520 surviving penguins pairs have been finding food - whether it is through rare cracks in the ice or if they are making the journey all the way to the edge.

Turney said the penguins appear unable to move to new colonies and there is no prospect for rescuing them by carving holes in the ice, as these would rapidly freeze over.

That leaves them at the mercy of the iceberg.

Turney and his colleagues concluded that “unless the B09B relocates or the now perennial fast ice within the bay breaks out” the Adélie penguin colony of Cape Denison could be no more in two decades time.

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Penguin parents: Inability to share roles increases their vulnerability to climate change

10-Feb-2016

Young penguins suffer at feeding time due to an inflexible division of parental duties

Springer

IMAGE: The fixed division of labor between crested penguin parents increases their chicks' vulnerability to food shortages made ever more common by climate change.

Credit: Kyle Morrison

The fixed division of labour between crested penguin parents increases their chicks' vulnerability to food shortages made ever more common by climate change. The parents have been unable to adapt their habits to the challenges of increasingly frequent years of limited food supply and, as a result, will become further threatened by extinction. So says Kyle Morrison of Massey University and the National Institute of Water & Atmospheric Research in New Zealand, who led a study published in Springer's journal Behavioral Ecology and Sociobiology.

The main duties of all penguin parents are to provide food and to defend their offspring against predatory seabirds and other intruding penguins. While on guard duty, parents fast and do not go off to sea to feed. Most penguins avoid long fasting periods by alternating brooding and chick-provisioning duties between the sexes. However, the seven species of Eudyptes penguins (the crested penguins, including rockhopper penguins) are an exception. Males guard and fast for the first three to four weeks after eggs have hatched. During this time, females are the sole providers. During the next six weeks, chicks gather together in crèches and can be fed by both parents. During this crèche phase, both sexes may make extended multi-day trips to sea to regain weight.

These parental roles never vary, no matter what the environmental conditions. However, how frequently each sex brings food to their chick can change drastically between years, depending on how much krill, fish, and squid the parents can find. Eudyptes populations have already seen worrying long-term declines, especially because of climate-induced food shortages.

The researchers studied Eastern Rockhopper Penguins (Eudyptes chrysocome filholi) on New Zealand's sub-Antarctic Campbell Island over two consecutive breeding seasons. During the 2011 season, abundant food was available, but 2012 was a lean year. The researchers noted how often chicks were fed, their subsequent size at one month old, and the colony's overall success in raising chicks. Data-loggers installed along a narrow travel pathway from the sea were used to gather accurate data on how much time tagged adult birds spent away from the island and how frequently they returned to feed their chicks.

Morrison and his team found that chicks were hatched and reared more successfully during the 2011 season than in 2012's lean months. During the 2012 crèche phase, males in particular spent more time at sea in search of food to regain the mass they lost during their chick-guarding fast ashore. This made males less likely to regularly bring food to their offspring. Chicks that were fed less also grew more slowly.

The results show that these penguins' rigid division of parental roles is not suited to ensure that their chicks grow and survive as well as possible, especially in times of poor food supply. The situation is expected to become worse with increasing climate change. The researchers estimate that if Eudyptes penguins were to share guarding and foraging duties equally, up to 34.5 percent more feeds could be provided to their chicks. However, changing their breeding strategy isn't a simple matter, because the smaller, less aggressive females would be less effective in the role of guarding chicks.

"Eudyptes penguins, ostensibly anchored in a reproductive strategy maladapted to a marine environment where food availability is less predictable, will continue to be highly threatened by climate change," warns Morrison.

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Reference: Morrison, K. et al (2016). The canalized parental roles of a Eudyptes penguin constrain provisioning and growth of chicks during nutritional stress, Behavioral Ecology and Sociobiology, DOI 10.1007/s00265-016-2060-z

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New twist in the case of the little blue penguin

Wednesday Feb 3, 2016
By Jamie Morton  

Jamie Morton is the NZ Herald's science reporter. 

Researchers have revealed an Otago population of the world's smallest - and possibly cutest - penguin species actually hailed from across the Tasman. Photo / Supplied

The curious case of a huddle of Aussie invaders that long managed to blend in with our native little blue penguins has just taken another mysterious twist.

Researchers recently revealed an Otago population of the world's smallest -- and possibly cutest -- penguin species actually hailed from across the Tasman and have now confirmed the immigrants arrived as recently as the past few hundred years.

It's the latest instance in which DNA analysis has dramatically changed what we know about many of our supposedly native species.

Following startling findings in December that, for the first time, described two distinct species of little blue penguin in New Zealand, a paper published today in the Proceedings of the Royal Society B: Biological Sciences finds the newcomers probably arrived here between 1500 and 1900.

This up-ended previous theories that the Australians had been here for thousands of years.

As part of her PhD research at Otago University, Dr Stefanie Grosser analysed ancient DNA from the remains of more than 100 little penguins, including bones dating back to pre-human times and specimens from archaeological deposits and museums. "Amazingly, all of the bones older than 400 years belong to the native New Zealand species," she said.

Dr Grosser said the arrival apparently followed the decline of the native penguin, which early human settlers and introduced predators hunted.

The Australian species were set apart by a few subtle differences in their colour, body and cranium size.

Other researchers had previously shown that calls differed between Australian and New Zealand little penguins and females preferred the calls of males of their own species. "You could say the Aussies like hearing 'feesh', while 'fush' sounds better to Kiwi ears," Dr Grosser joked at the time of the December findings.

But how they got here remains a mystery -- and one we might never solve. "It's one of those unlikely events that they happened to rock up on the Otago coastline and got a foothold," said study leader Professor Jon Waters, of Otago University's Department of Zoology. "You could make up a story that maybe an Australian ship picked up 10 and brought them over, but I'd find that really hard to believe."

The Australian sub-population appears confined to Otago. DNA analysis from other colonies, such as Wellington, Kaikoura and Banks Peninsula, turned up only the New Zealand lineage. "It's possible we might find another colony of Aussies somewhere like Fiordland, we don't know."

Professor Waters believed the findings should bring about a different approach to the species' conservation. "We have to think about them as being not one thing, but two, and manage them separately -- so there might be a real paradigm shift."

The native penguin, which on average stands at just 25cm and weighs 1kg, is considered in decline in New Zealand. Dogs pose their greatest threat.

The research, supported by the Marsden Fund and the now-closed Allan Wilson Centre, also provides the latest example of penguins winding up on foreign shores far from home.

Little blue penguins have been found as far as Patagonia in South America.

Other famous penguin stories have included the Antarctic emperor penguin Happy Feet, which captured Kiwi hearts after it arrived in Kapiti in 2011, and Katrina, a Fiordland penguin that swam 3000km to Mt Gambier, South Australia, in 2013.

How DNA has redefined our native species

The yellow-eyed penguin

DNA analysis and carbon-dating led to findings published last year that revealed a change-over between the yellow-eyed penguin and another penguin species that became extinct around the same time as the moa.

An Otago University team showed the waitaha, which was slightly smaller than the yellow-eyed penguin, vanished within 200 years of Polynesian settlement of New Zealand, before 1500AD.

In one of the most rapid biological transition events documented, the yellow-eyed penguin, or hoiho -- considered one of the world's rarest penguin species with a population of between 6000 and 7000 -- moved to the mainland from the subantarctic islands and replaced the waitaha within just a few decades, in the early 1500s.

The New Zealand sea lion

That research had fascinating parallels with the fate of a pre-historic species of New Zealand sea lion, which once dominated South Island shores before they became extinct as recently as between 1300 and 1500AD, soon after Polynesian settlement.

DNA analysis reported in 2014 showed their place on the New Zealand mainland was quickly taken by today's modern population, which was previously limited to the cold waters of the subantarctic.

The kiwi

2014 was also the year that scientists corrected the shocking suggestion that our national bird arrived here when its winged ancestor flew in from Australia.

The 150-year-old mystery was finally solved by DNA sequencing that revealed the bird was more closely related to the extinct, 2.3m tall elephant bird, a native of Madagascar.

The moa

A separate study in 2014 put even more genetic distance between the extinct moa and their old bush mates, the kiwi.

DNA-based research led by New Zealand scientist Professor Allan Baker suggested the giant birds were more closely related to a flying South American bird still alive today than our national icon.

The South American tinamous, one of the world's most ancient living groups of bird, can fly and are not categorised as ratites, but are considered close relatives because of the shared structure of their palate bones.

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Penguin chicks huddle up for heat, protection

Posted By Science Codex News on February 3, 2016

Location and environmental conditions may influence when gentoo chicks huddle in cold, wet Antarctic conditions, according to a study published February 3, 2016 in the open-access journal PLOS ONE by Caitlin Black from the University of Oxford, and colleagues.

Many penguin species form aggregations for conserving heat, providing protection, and other purposes. Scientists have observed gentoo penguins aggregating during the post-guard period, a period when the parents leave the chicks without waterproof feathers daily to go find fish, but these aggregations have never been studied over a large spatial range in the Antarctic. The authors of this study observed the gentoo penguin aggregation behavior across four study sites along a latitudinal gradient. To examine the adaptive benefit of aggregations, they observed each colony during the post-guarding period of the 2012-2013 breeding season using time-lapse cameras.

The authors found that gentoo chick aggregations help individual chicks save energy during wet, cold conditions. However, they also found significant differences in aggregation behavior between colonies. Chicks form aggregations more often and in a larger size at the northern-most colony studied on the island of South Georgia than at the southern study sites on the Antarctic Peninsula, suggesting this behavior may be colony specific. Since not all post-guarding periods occurred during the same time period at each study site, the differences in environmental conditions and post-guard period timing may have also played a role. The authors suggest their results highlight the need for studies to evaluate multiple seabird colonies within one species before generalizing behaviors based on one location.

Caitlin Black notes, "Behaviors, such as chick aggregations, influence whether a chick will survive and therefore may greatly impact the success of a colony. The results show why we must evaluate behaviors at multiple locations, as these behaviors are often colony specific and cannot be generalized from one year at one location."

Source: PLOS

 

Science Codex source

Ancient DNA Analysis Hints at Recent Arrival of Australian Little Blue Penguins in New Zealand

Feb 03, 2016

|

a GenomeWeb staff reporter

 

                                         Tatiana Gerus/Wikimedia Commons

 

NEW YORK (GenomeWeb) – An ancient DNA analysis has found that the Australian little blue penguin is a recent colonizer of New Zealand, according to a University of Otago-led team of researchers.

By radiocarbon dating and sequencing stretches of ancient DNA from Eudyptula samples found in New Zealand, researchers led by Otago's Jonathan Waters found that the Australian Eudyptula novaehollandiae likely arrived in New Zealand some 500 years ago, around the time of the decline of the indigenous Eudyptula minor. As they reported yesterday in the Royal Society Proceedings B: Biological Sciences, the researchers found that the decline of a native species could thus be masked by the introduction of a related taxon.

"Our results clearly show that the Australian penguin colonized Otago very recently, between 1500 and 1900 AD, apparently following the decline of the native New Zealand little penguin, which was hunted by early human settlers and introduced predators," first author and Otago researcher Stefanie Grosser said in a statement.

The little penguin genus is endemic to both Australia and New Zealand, and recent genetic analysis of mitochondrial DNA had found that there are two, divergent little penguin lineages: one that's found only in New Zealand and one that's found both on New Zealand's Otago coast and in southern Australia. Initial genetic studies had suggested that the Australian penguin had been in New Zealand for thousands of years, though a more recent study hinted at a later introduction.

Waters, Grosser, and their colleagues collected 146 prehistoric Eudyptula bones from museum and archaeological collections and nine historic Eudyptula samples that represent the full swathe of the little penguin range in New Zealand. They extracted and sequenced a 393-basepair stretch of DNA corresponding to the mitochondrial control region HVRI from 128 of those specimens, though 16 of those could only be partially sequenced.

At the same time, radiocarbon dating of nine of the prehistoric Eudyptula bones traced one sample as far back as 34,000 years before present (BP) — the oldest yet discovered, the researchers noted — though most of the others dated back to 1499 BP and 1112 BP.

The genetic analyses revealed a striking turnover in Otago, the researchers reported: E. minor was nearly completely replaced by E. novaehollandiae. All 119 Holocene samples — older than 1600 AD — were phylogenetically assigned to the endemic New Zealand E. minor lineage, while the more modern penguin samples were mostly E. novaehollandiae. Five of the six museum skin samples from birds collects in 1969 had Australian haplotypes, the researchers added.

Their analysis further found that the prehistoric New Zealand Eudyptula exhibited substantial haplotype diversity. Some of the ancient diversity has been lost as the research found that only two of the 12 detected prehistoric New Zealand haplotypes are represented in the modern samples. This, they added, indicates a haplotype diversity reduction of 35 percent.

Using a Bayesian serial coalescent approach, the researchers examined the demographic history of the Australian little penguin in New Zealand. After modeling a number of scenarios, they found that there was the most support for a two-step model in which an initial invasion of E. novaehollandiae was followed by a population expansion in Otago. Under this model, colonization likely took place about 25 generations ago, or in about 1500 AD to 1890 AD with an effective population size of the colonizers of about 2,900 individuals.

This timing, the researchers noted, broadly coincides with a 40 percent population loss of the endemic E. minor. However, they added that they had insufficient power to determine whether the E. novaehollandiae colonization or decline of E. minor occurred first.

Human colonizers, who arrived a few centuries prior, are thought to have aided in the E. minor decline likely due to hunting and the introduction of predators like the Polynesian rat and dog.

"[O]ur aDNA analyses of little penguins directly document a compelling example of rapid faunal shift coinciding with human expansion into New Zealand," the researchers wrote in their paper. "These data highlight that the decline of a native species can be masked by the cryptic invasion of a related species."

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