Ancient botanical ink between far-flung Polynesian cultures, and why does Pitcairn keep showing up?

Polynesian voyagers visited nearly every island in the tropical and subtropical Pacific, and they colonized and remained on most of them.

But a remarkable few were abandoned, despite apparently having the resources to maintain a population. Pitcairn is one of those.

This remote high island in the eastern South Pacific is best known as the refuge that the Bounty mutineers and their Tahitian friends went to, to hide from the British navy. Pitcairn was uninhabited at the time. But it had been inhabited.

Canoe-sailing Polynesians had moved there a millenium ago, apparently thrived for 400 years, and then vanished. Like a sailing ship found drifting with no one aboard, its story is a mystery. Even today, as a British Overseas Territory, it has difficulty attracting people. An immigration site for Pitcairn is here. 

There is something eerie about Pitcairnʻs Polynesian history. Where did these islanders go? Did they abandon their island. Were they killed off by disease? Did war play a role? Or starvation?

One thing they may not have been is alone. 

In a major study of the Pacific-wide connections between island samples of paper mulberry (wauke, or Broussonetia papyrifera), which this blog covered in an earlier post, the plants collected on Pitcairn display deep genetic connections to Polynesiaʻs ancient past.

Wauke was a canoe plant—one of the critically important plants that all Polynesian voyaging canoes carried on their missions of colonization. It was important because it was the key plant for making fabric.

In studying the genetic differences and similiarities of wauke collected on different islands, the researchers found that Pitcairnʻs plants had strong genetic roots elsewhere in Polynesia.

For example, they found that "New Guinea is directly connected to Remote Oceania through Pitcairn."

There are distinct cultural differences between portions of Polynesia that were occupied at different times. For example, Fiji, Tonga and Futuna are an older Polynesian culture, which the authors call Western Remote Oceania (WRO). Islands like Niue, the Cook Islands, the Marquesas, the Austral Islands and Rapa Nui are understood to have been populated later. They are called Eastern Remote Oceania (ERO). New Guinea, in Near Oceania is outside that range and is considered even older in Polynesian history.

Yet, then there is Pitcairn.

"We found Pitcairn plants in a pivotal position between WRO and ERO. In addition, Pitcairn accessions linked with genotypes from New Guinea in Near Oceania," they write.

How to explain that? Pitcairn is physically in the newer area of Eastern Remote Oceania. Yet its wauke tells a different story, a story of ancient connections: "The link between these... groups was Pitcairn," the researchers write.

But the authors suggest that this does not suggest that Pitcairn was an ancient voyaging crossroads that maintained voyaging connections across thousands of miles of open sea. "We do not propose a direct migration route from New Guinea to Pitcairn," the authors write.

The explanation, they suggest, is simpler.

Pitcairn was occupied so long ago, and also abandoned so long ago, that it retained the ancient genetics of the wauke that the earliest voyagers carried with them.

"This relationship between samples from New Guinea and Pitcairn represents the survival of old genotypes on Pitcairn Island due to centuries of isolation after initial colonization by Austronesian speaking peoples. We suggest that these genotypes were probably lost on other islands that represent the intermediate steps of dispersal and migration," they write.

Hawaiʻi, the Marquesas, Rapa Nui (Easter Island) and Pitcairn are also linked genetically through wauke.

"The connections observed in our study through the genetic analysis of paper mulberry plants... show ties between Rapa Nui and Marquesas and between the Marquesas and Hawaii," the write.

Ultimately, the work confirms the conclusion that all Polynesia is connected, and that a thousand years ago, this stone age culture was tightly connected.

©Jan TenBruggencate 2019

Wauke tracks Polynesian voyaging routes: New genetic studies

Fiji kapa making. 

Credit: Andrea Seelenfreund

Genetic studies of one of the key canoe plants, wauke, appear to confirm Polynesian voyaging from west to east across the Pacific, but also identify key regions of voyaging.

Wauke, also known as paper mulberry or Broussonetia papyrifera, is the raw material for some of the best Hawaiian and Polynesian kapa or bark cloth. It also produces edible fruit. And interestingly, most of Polynesia only has female plants, while the Hawaiian Islands have both males and females.

How does that happen? The Hawaiian males apparently were brought to these islands after European contact. That will be reviewed later.  On all other Polynesian islands, all plants found today are female, but the research did find a couple of examples of male plants in samples from the early 20th century from the Marquesas and Rapa. 

This is confusing. The authors of one study on the subject said it could be that wauke males were included in early voyaging, and have since disappeared, leaving the plants to be reproduced only by human involvement. But there is an odd alternative possibility. The Broussonetia clan is known to occasionally undergo sex reversion, in which female plants may rarely produce male flowers, or males may change to females. 

Wauke

Credit: USDA, J.S. Peterson

Hawai`i is different from the rest of Polynesia because it still has male wauke. But those do not appear to be from early Polynesian introductions. Rather, the males apparently descend from a separate, non-Polynesian introduction to the Islands by 19th century Asian immigrants. The male wauke do not appear to have come through Polynesia, like the females. You can read more about the sexual distribution of the paper mulberry here. 

"Most paper mulberry plants now present in the Pacific appear to be descended from female clones introduced prehistorically," the authors of that paper write.

The dominant wauke stock in the Pacific appears to have originated in Taiwan, where, as in China and Indochina, it is native. But as a valued canoe plant, it was carried by Polynesian voyagers virtually everywhere they went. The plants are found not only in Hawai`i but at New Caledonia, Fiji, Samoa, Wallis and Tonga, in the Marquesas, the Society Islands, the Austral islands (Rapa), Pitcairn and Rapa Nui or Easter Island.

Wauke is a dioecious plant, meaning that male and female flowers occur on different plants. Because the existing plants are all female, the Polynesian wauke can't reproduce itself, and needs human help being transported and being kept alive.

"In the absence of breeding populations, the spread (i.e. movement) of paper mulberry depends entirely on a continuous human cultural tradition of preserving, propagating and transporting the plant," wrote the authors of the paper cited above.

In a new paper, many of the same authors, add to the story of the wauke. The latest paper, published this year in the journal PLOS One, is entitled "Human mediated translocation of Pacific paper mulberry [Broussonetia papyrifera (L.) L’He ´r. ex Vent. (Moraceae)]: Genetic evidence of dispersal routes in Remote Oceania."

The authors are from Chile, New Zealand and Taiwan. They include Gabriela Olivares, Barbara Peña-Ahumada, Johany Peñailillo, Claudia Payacan, Ximena Moncada, Monica Saldarriaga-Cordoba, Elizabeth Matisoo-Smith, KuoFang Chung, Daniela Seelenfreund and Andrea Seelenfreund. 

A Eurekalert press release on the study, which is simpler reading. 

The researchers conducted genetic studies on samples of wauke from 380 modern and museum samples from 33 islands across the Pacific.

They found that while all those female wauke are presumably clones of an original import, there is still some genetic diversity, and it can help understand migration patterns within the remote islands of Oceania.

"Our data detect a complex structure of three central dispersal hubs linking West Remote Oceania with East Remote Oceania. despite its vegetative propagation and short timespan since its introduction into the region by prehistoric Austronesian speaking colonists," wrote co-author Andrea Seelenfreund.

The three clusters where the wauke are most closely related to each other are: 1. Tonga and Fiji; 2. The islands of Samoa, Wallis and New Caledonia; 3. and then all of eastern Polynesia, including Hawai`i, Tahiti, the Marquesas Islands, Austral Islands and Rapa Nui.

There is evidence that Hawai`i had a more complex wauke heritage than other islands. Not counting the modern importation of male plants, it appears that traditional Polynesian strains of wauke came from both eastern Polynesia and Tonga in separate importation voyages. That adds an odd wrinkle to migration theory.

There seems to be a suggestion in the data that the wauke traveled between Taiwan and New Guinea, and from there into the rest of Polynesia. There are also suggestions that the wauke traveled on all voyaging canoes that were in the process of colonizing new areas, but after that were likely not on subsequent back-and-forth voyages.

"Crops important for survival and cultural reproduction were probably aboard all colonizing canoes, although probably not part of later inter-archipelago commercial networks or part of ritual exchanges of high valued objects, such as textiles, adzes, whale teeth, shells and other items between established settlements," the authors wrote.

© Jan TenBruggencate 2019

Controlling rats doubles `elepaio nesting success, and other conservation success stories

Hawai`i `elepaio, Image: Kelly Jaenecke, USGS

A new study, published this year in the journal The Condor, found that removing black rats from a forest environment quickly improves the ability of the native `elepaio to bounce back.

It is part of a growing body of evidence that removing rats from environments where they are not native can significantly improve bird survival and forest recovery. 

And unexpected benefits can happen. As when black rats were removed from Palmyra Atoll. While it was mainly intended to protect seabirds and native crabs, the removal also wiped out the Asian tiger mosquito, Aedes albopictus, which carried disease. It turned out the mosquitoes needed the rats as a blood source.

And with rats gone, suddenly the Palmyra forest floor burgeoned with seedlings of native trees.

The new `elepaio study is entitled, "Increased nesting success of Hawaii Elepaio in response to the removal of invasive black rats." You can find it here. Authors are Paul C. Banko, Kelly A. Jaenecke, Robert W. Peck and Kevin W. Brinck.

It's not news that rats are toxic to the natural environment in the Islands. They eat everything--seeds, seedlings, eggs, adult birds, insects and lots more. What's new here is clear proof of the direct impact on one important deep forest species.

"In Hawaii and other oceanic islands with few native land mammals, black rats (Rattus rattus) are among the most damaging invasive vertebrate species to native forest bird populations and habitats, due to their arboreal behavior and generalist foraging habits and habitat use," the authors wrote.

There are models that suggest that growth rates for native bird species populations should respond well to removing rats, but there hasn’t been a lot of evidence—mainly because that evidence is hard to get. Many of the critical native forest birds are rare, their nests are hidden and hard to observe and they can be high in trees.

One reason black rats are a special problems is that they climb trees, and will take females and eggs right off the nest. There are wildlife video images of it.

"Lower female survival rates have been attributed to nest predation by rats for a number of Hawaiian species," the authors write.

"Hawaiian forest bird nesting studies have indicated that rats are an important cause of nest failure for at least the Oahu Elepaio in lowland mesic forests dominated by invasive fruit-bearing tree species and for the Puaiohi in wet montane ‘ōhi‘a forests." O`ahu `elepaio are known to science as Chasiempis ibidis, and puaiohi or small Kaua`i thrush as Myadestes palmeri.

In the paper's study, researchers used rodenticide to reduce rat populations by 90 percent in two Hawai`i Island forest areas, each 120 acres in size, along the Mauna Loa Strip Road in Hawai`i Volcanoes National Park. They also trapped rats, catching thousands of them.

Their finding: Once the rat populations were reduced, for the Hawai`i puaiohi or Chasiempis sandwichensis, nesting success doubled, from 33 to 62 percent, and female survival also increased dramatically.

"The rapid response of Hawaii Elepaio to rat removal indicates that predator management could be a powerful tool for restoring the entire forest bird community. Hawaii Elepaio are representative of other forest bird species because they nest in a variety of widespread, abundant tree species and they build their nests throughout the forest canopy," they wrote.

And one of the benefits of keeping the bird numbers elevated, they argue, is to give the species time. Time to evolve natural resistance to one of the other critical threats, mosquito-borne avian malaria.

It's good news for conservation. 

Another bit of positive news from a couple of years ago was that native forest birds like the `elepaio quickly inhabit newly established native forest areas.

It's another case of, if you build it, they will come.

© Jan TenBruggencate 2019

Bee swarm visits, leaves a pristine waxen gift

Itʻs June and that means the beehives are overfull with bees--swarm season.

Iʻve had two swarms come through my yard this week. One took up residence in an old empty hive box, but the other was just passing through.

A basketball sized bunch of bees hung under a loulu palm frond for a few hours this morning.

They were not aggressive. I could walk right up and photograph them. 

And then they seemed to get message--perhaps scout bees had found a likely home. 

A bunch of them left the clump and swirled up into the air. And then the swarm came apart, fist-sized clumps of bees falling off and flying up into the air.

They swirled up in a great buzzing storm, right above the palm tree on which they had perched.

The cloud of bees began extending itself to the south, and in another minute, they were gone.

Swarm hangs under loulu frond

The only evidence that they had been there was a cell-phone-sized pristine white wax comb.

Swarm starts to break up, leaving the palm.

All the remains is a bit of wax comb.