Ancient Karst Reef Sinkholes On The Ewa Plain Hold Secrets To Oahu’s Earliest Residents

Looking Back by Looking Down 

By Chad Pata, August 22, 2014  Go Kapolei Magazine

http://gokapoleimagazine.com/history/looking-back-looking/

In general, sinkholes are created over centuries as the acidity of rainwater eats away at the limestone, causing underground caverns to form and eventually give way to the weight of the earth above them.

Here in Kapolei, anyone who has ever put a shovel in the ground knows that the entire plain is made up of an ancient reef that dried up as ocean waters receded 120,000 years ago. This weathered karst, as it is known, is a limestone substrate that through the centuries was eaten away by the rains creating thousands of vertical bell-shaped caves or sinkholes.

While they are—geologically speaking—of some interest, their true value comes from their unintended ability to serve as a trap for animals. Due to their vertical nature, once a creature found itself in such a place, there was little chance of escape as scaling the walls was impossible and rare is the bird that can hover straight up like a helicopter to escape these narrow confines.

So what we had was a perfect repository to collect fossils of the wildlife that occupied these islands long before the Polynesians ever set foot on this volcanic chain.

Unfortunately, 99 percent of these “fossil tombs” have either been bulldozed for agricultural lands, lain over with concrete for development or simply lost to the ever-shifting sands of time, which brings us back to our little six-acre plot in Kapolei.

They were first discovered in the 1970s by Jennie Peterson, an archaeologist with Bishop Museum, as she was doing an environmental impact study on the once-proposed Deep Draft Harbor, but the history of the sinkholes would be written by local zoologist Dr. Alan Ziegler who spent decades exploring, documenting and teaching others about the wonders to be found out here on the Plain.

Eventually, the Smithsonian got involved with the project and the preeminent avian paleontologists Storrs Olson and Helen James came in to examine the remains.

What they found was astounding. More than 40 extinct species were interned in the sinkholes and of whose existence no one had known until they were discovered here.

There were remains of sea eagles and hawks, flightless rails and finches, and most shocking of all the moa nalo, which in Hawaiian means “lost fowl.” It was a three-foot tall flightless goose-like duck with a head like a tortoise. Many of the remains were in articulated form, as they had most likely died in the sinkhole after having fallen in, giving scientists an unadulterated look into our distant past.

“Back in the day, with all these birds, it must have been quite a raucous place!” says Marjorie Ziegler, daughter of Alan and executive director for the Conservation Council for Hawai‘i who hopes to oversee the care of the preserve one day.

Many of these remains now reside in Washington, D.C. at the Smithsonian and while the important artifacts have been removed, there is still much for future generations to learn at this holdover from pre-human contact Hawai‘i.

For years the CCH and Hawai‘i Nature Center led tours to the sinkholes, allowing children a chance to play archaeologists for a day. Ladders would be set up, many of the holes are 8-feet deep, and the kids would descend into the depths to use trawls, scoop sand and bring buckets of it to the surface.


Here they would use screens to discover the bones of Hawaiian petryls, the ‘ua‘u, that is only found on neighbor islands now and the beaks of long-gone crows who used to call O‘ahu home. They would always return the remains to the sinkhole to allow the next group to discover them.

But in recent years, invasive species of plants have overgrown the property, the holes are obscured by weeds making it difficult to find them or, even worse, hard to see their openings until you are falling into one.

The sea air and vandals have ravaged the fencing; and while still protected on paper, Ziegler is concerned about what could happen to this valuable natural resource.
“I worry less about homeless people setting up camp in there than about the accidental bulldozer collapsing them,” says Ziegler.

The holdup on the turnover of the land to the DLNR is a modern-world one.

The property cannot be conveyed until the surrounding land is subdivided and the subdivision cannot happen until there is improved road access to the surrounding industrial park development. This development, named Kapolei Harborside is planned to happen over the next decade, so while the plan is still to turn the land over to the DLNR, it may be some time before the public gets to visit this important bit of our area’s history.

When this lot at the corner of Malakole and Hanua streets is officially turned over, Ziegler and her team at CCH have big plans for the sinkholes starting with clearing the land of all the invasive species, including many large kiawe trees, and marking the sinks so that the visitors can be safe when visiting.

Next will be to build an educational area where kupuna can talk about these extinct species before kids go visit the sinkholes. And here, Ziegler’s visions can finally be realized, as amongst the remains our ancient past, the minds of our future can grow.

For more on the Conservation Council for Hawai‘i, log on to www.conservehi.org

SINKHOLE BIRDS THAT ARE EXTINCT

Extinct species of birds from sinkholes on the 'Ewa Plain:

Pterodroma jugabilis, a medium-sized petrel
Thambetochen xanion, a large flightless species of waterfowl (moa nalo)
Branta (uncertain species), a weak-flying goose, closely related to the nene
Porzana ziegleri, a small flightless rail
Porzana ralphorum, a large flightless rail
Circus dossenus, a small harrier, apparently adapted to feed on forest birds
Grallistrix geleches, a long-legged, bird-eating owl
Corvus impluviatus, a raven-sized crow with a deep, arched bill
Corvus viriosus, a raven-sized crow with a long, straight bill
Myadestes oahuensis, the O'ahu thrush
Moho apicalis, the O'ahu 'o'o (a honeyeater)
Chaetoptila (related to) angustipluma, a large honeyeater
Telespiza persecutrix, a small finch similar to the Laysan and Nihoa finches
Chloridops wahi, a grosbeak finch similar to the extinct Kona finch of the Big Island.
Chloridops regiskongi, a grosbeak finch with a really large bill, nicknamed King Kong finch.
Rhodacanthis litotes, similar to the extinct koa-finches of the Big Island.
Xestospiza fastigialis, a finch with a conical bill that was once common on O'ahu, Moloka'i and Maui.
Hemignathus upupirostris, an 'akialoa (Hawaiian honeycreeper with a long, thin, decurved bill)
Aidemedia chascax, a Hawaiian honeycreeper with a long, straight bill
Aidemedia zanclops, a Hawaiian honeycreeper with a sickle-shaped bill
Ciridops (uncertain species), a short-billed, strong-legged Hawaiian honeycreeper of a type previously known only from the Big Island.

SINKHOLE BIRDS STILL THRIVING

Sinkhole birds that are not extinct:

Pterodroma sandwichensis, the Hawaiian petrel; not previously known from O'ahu but bones are abundant in the sinkholes, showing that the region once had a major colony.
Haliaeetus (related to) albicilla, the white-tailed sea eagle. These eagles were either resident in the Islands or were regular visitors in the past. (A sea eagle was spotted on Kaua'i and possibly on O'ahu late last year and earlier this year.)
Telespiza cantans, the Laysan finch, known historically only from Laysan Island.
Loxioides bailleui, the Palila, known historically only from high-elevation Big Island mamane-naio forest.

Source: Helen James, Smithsonian Institution

Oahu's Ewa Plain Karst Sinkholes And Caves Yield Extinct Bird Fossils

 http://ewa-hawaii-karst.blogspot.com/2015/01/ewa-plain-karst-sinkholes-and.html

US Fish Wildlife Demonstrates How 

Ewa Plain Karst Can Be Restored

 http://ewa-hawaii-karst.blogspot.com/2014/12/us-fish-wildlife-ewa-preserve.html

Oahu's Ewa Plain Karst Sinkholes And Caves Yield Extinct Bird Fossils

Oahu's Ewa Plain Karst Sinkholes And Caves Yield Extinct Bird Fossils 

By Jan TenBruggencate, Advertiser Science Writer  August 7, 2007 

http://the.honoluluadvertiser.com/article/2007/Aug/07/ln/hawaii708070352.html

SINKHOLE BIRDS THAT ARE EXTINCT

Extinct species of birds from sinkholes on the 'Ewa Plain:

Pterodroma jugabilis, a medium-sized petrel

Thambetochen xanion, a large flightless species of waterfowl (moa nalo)

Branta (uncertain species), a weak-flying goose, closely related to the nene

Porzana ziegleri, a small flightless rail

Porzana ralphorum, a large flightless rail

Circus dossenus, a small harrier, apparently adapted to feed on forest birds

Grallistrix geleches, a long-legged, bird-eating owl

Corvus impluviatus, a raven-sized crow with a deep, arched bill

Corvus viriosus, a raven-sized crow with a long, straight bill

Myadestes oahuensis, the O'ahu thrush

Moho apicalis, the O'ahu 'o'o (a honeyeater)

Chaetoptila (related to) angustipluma, a large honeyeater

Telespiza persecutrix, a small finch similar to the Laysan and Nihoa finches

Chloridops wahi, a grosbeak finch similar to the extinct Kona finch of the Big Island.

Chloridops regiskongi, a grosbeak finch with a really large bill, nicknamed King Kong finch.

Rhodacanthis litotes, similar to the extinct koa-finches of the Big Island.

Xestospiza fastigialis, a finch with a conical bill that was once common on O'ahu, Moloka'i and Maui.

Hemignathus upupirostris, an 'akialoa (Hawaiian honeycreeper with a long, thin, decurved bill)

Aidemedia chascax, a Hawaiian honeycreeper with a long, straight bill

Aidemedia zanclops, a Hawaiian honeycreeper with a sickle-shaped bill

Ciridops (uncertain species), a short-billed, strong-legged Hawaiian honeycreeper of a type previously known only from the Big Island.

SINKHOLE BIRDS STILL THRIVING

Sinkhole birds that are not extinct:

Pterodroma sandwichensis, the Hawaiian petrel; not previously known from O'ahu but bones are abundant in the sinkholes, showing that the region once had a major colony.

Haliaeetus (related to) albicilla, the white-tailed sea eagle. These eagles were either resident in the Islands or were regular visitors in the past. (A sea eagle was spotted on Kaua'i and possibly on O'ahu late last year and earlier this year.)

Telespiza cantans, the Laysan finch, known historically only from Laysan Island.

Loxioides bailleui, the Palila, known historically only from high-elevation Big Island mamane-naio forest.

Source: Helen James, Smithsonian Institution

Oahu sinkholes yield extinct birds

The baking sun and thorny kiawe trees of Kapolei hide dense caches of history, relics from a time when the 'Ewa Plain was a dense forest alive with strange birds now long extinct.

In those years, before the arrival of humans, the amazing moa nalo lumbered through the trees. It was a 3-foot-tall, flightless gooselike duck — the largest of the Native Hawaiian birds. Flightless rails and geese waddled around with it. Overhead flew a sea eagle, owls, crows, a hawk and bats. Finches and other perching birds flitted among the trees.

Most of these birds have been extinct for hundreds of years.

But proof of their existence lies in the bottom of limestone "sinkholes" where they sometimes were trapped and died, leaving their bones and beaks behind. The shells of now-extinct tree snails, and the pollen from the plants that once forested this area are found in sediments with the bones.

The sinkholes are vertical caves in an ancient reef that grew during a period 120,000 years ago when sea levels were much higher. There once were thousands of sinkholes across the 'Ewa Plain — time traps that preserved evidence from Hawai'i's prehistory.

Most have already been filled or covered by development.

Kapolei Property Development, which is proposing a 350-acre light industrial park at Kapolei, plans to preserve a six-acre parcel of undisturbed land that contains several of the sinkholes.

A chain-link fence, stained pale brown with the coral dust of the region, protects the acreage.

"This area hasn't been touched," said Steve Kelly, manager of development for Kapolei Property Development. "It was fenced in the early 1990s by the Estate of James Campbell, and we plan to put a new fence around it. We will be looking to pass on the property to some appropriate entity."

Scientists and community leaders cheer the firm's decision.

"This is a community resource, a place where people can come and learn about the past," said Ati Jeffers-Fabro, an environmental educator who has brought kids to the sinkholes to learn natural history.

"This is all we have left of a unique geological and biological setting in these Islands," said Helen James, a fossil bird expert at the Smithsonian Institution, who with her former husband, Storrs Olson, has taken the lead in identifying the ancient bones and beaks. "For future understanding and research of the Islands' natural history, we should preserve this."

The Conservation Council for Hawai'i is spearheading the effort to ensure protection for the sinkholes. Council executive director Marjorie Ziegler said the organization would like the six-acre plot to be transferred to the Department of Land and Natural Resources, perhaps designated as a state Natural Area Reserve. But if not that organization, some other caretaker should be established, she said.

Key goals are protection, scientific research, public education and the possible reforestation of the area with some of the native plants that the pollen record proves once lived here, Ziegler said.

The first person to find bird bones in sinkholes here was Jennie Peterson, now the environmental education program manager with the Hawai'i Nature Center. During the 1970s, she was an archaeologist with Bishop Museum, studying the area for an environmental impact statement on the then-proposed Deep Draft Harbor.

"I was digging in a large sinkhole when I found bones. They were so big that I thought they were mammal bones, but I knew they couldn't be because they were too light," she said.

'VANISHED FOWL'

No animal known to have lived in Hawai'i could have produced those bones, so she took them to Bishop Museum zoologist Alan Ziegler, Marjorie Ziegler's dad. He recognized they were the same class as extinct birds whose bones had been found in sand dune deposits on Moloka'i, and consulted with Olson, the Smithsonian Institution fossil bird expert, who happened to be conducting research on Maui.

It was a huge bird like nothing alive in the world today.

They called the group "vanished fowl," or moa nalo in Hawaiian. There are examples in the fossil record on all the major islands. The O'ahu moa nalo was given the scientific name of Thambetochen xanion.

A grazing animal, it looked most like a huge goose, but appeared to be most closely related to the dabbling ducks, said James, with the Smithsonian. The moa nalo had lost the ability to fly, and its flight muscles — robust in ducks and geese — were just thin straps across its chest, she said.

Further digging in sinkholes — some of them dry, and some with pools so deep that scuba gear was needed — yielded the bones of dozens of species of flightless birds, land birds, sea birds and raptors. The most common bones came from the ua'u, or Hawaiian dark-rumped petrel. This seabird has never been reported from O'ahu in historic times, but the fossil evidence shows there was an immense number of the birds here at one time.

"There must have been a major colony here. The whole 'Ewa Plain was just covered in them," James said.

When a team of visiting scientists, students and community members explored the six-acre Kapolei site last month, in a few minutes, one collected a handful of bones lying in plain view on the floor of a sinkhole. The collection included wing bones from ua'u and an extinct crow, skulls of ua'u and the beak of a very large, raven-sized extinct crow. The extinct crow has been named Corvus impluviatus.

Today, people think of the arid Kapolei area as former desert, but in pre-human times, it was forested.'

Researchers have found shells from extinct tree snails, and the pollen from the kinds of vegetation that probably once populated 'Ewa, including pritchardia palms, an acacia that was probably koai'a, and a critically endangered legume called kanaloa.

SURVIVAL PRECARIOUS

Once common, the kanaloa was found growing on Kaho'olawe, but its survival is exceedingly precarious, with just one plant in the wild and one in captivity. There has been no success in getting it to reproduce.

Preliminary dating of the sinkhole material suggests that most of the bird species were in the region for thousands of years, and most disappeared from the area in the years after human contact with the Islands. It is not yet clear what the direct cause was — perhaps humans directly feeding on birds, fire or other kinds of habitat disturbance, human-brought rats that could have both eaten vegetation and bird eggs, or something else.

Michigan State University zoology professor Peggy Ostrom is conducting studies to help answer some of the questions. She said she and her students will attempt to extract proteins from fossils for radio-carbon dating, and to analyze material in the bones to gain information about what the birds ate.

She and James also hope to find clues about the fate of the sinkhole birds.

"I'd be careful about making assumptions. It could have been a number of things," Ostrom said.

There is very little left of the prehistoric life of this region. Almost all the vegetation is modern weeds and hardy introduced trees like kiawe and banyan.

But deep in at least one of the wet sinkholes, in a tiny pool of brackish water, by the illumination from a flashlight, you can see tiny flickers of movement. They are the native anchialine shrimp — living in darkness and among the last survivors of the time when this region was alive with forms of life no living human has ever seen.

Oahu's Ewa Plain Karst Sinkholes And Caves Yield Extinct Bird Fossils

 http://ewa-hawaii-karst.blogspot.com/2015/01/ewa-plain-karst-sinkholes-and.html

US Fish & Wildlife Demonstrates How Ewa Plain Karst Can Be Restored

 http://ewa-hawaii-karst.blogspot.com/2014/12/us-fish-wildlife-ewa-preserve.html