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Ahinahina (Silversword)



At 10,000 feet we began to note the first tufts of •Ahinahina, the silversword, a marvelously hardy vestige of plant life. This spectacular creature which I have never observed elsewhere on the high mountain tops of Hawaii, is a veritable miracle. Clinging to the ground by its very deep roots, in form it resembles the aloes. Its sword-shape leaves are whitish gray, covered with light down. They glitter brilliantly as they catch the rays of the sun. From the center rises a stalk reaching as much as ten feet high.
–Charles De Varigny, French consulate secretary, 1857

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Plants which grow at the high elevations on Mauna Kea (11,000 – 12,000 feet) are particularly adapted to little rainfall, harsh weather, a huge ultra-violet impact from the sun and a cindery substrate that holds little water.

One of the most uniquely adapted plants in this alpine zone is the beloved ‘ahinahina or silversword. The leaves are thick and groove-shaped for catching rain. They are covered with a mat of tiny silver hairs that both reflect the heat of the sun and absorb whatever moisture there is from the passing mists.

Some of the magnificent ‘ahinahina on Mauna Kea live up to 50 years before flowering once and dying.

The Hawaiian word hinahina means “silver” or “gray.” At one time ‘ahinahina were so abundant on the mountain that cowboys sang songs about the blinding glare from the reflection of the sun on their leaves.

The ‘ahinahina is found only on the islands of Maui and Hawai‘i.


Vanishing species
Originally widespread across the slopes of Mauna Kea, the plant was victim, like so many others, to the browsing and rooting of cattle, sheep and goats that were introduced to the islands in the late 18th century.

The upper limit of the mamane tree is not far from 10,000 feet. The Raillardia, apiipii, extends a thousand feet higher. The beautiful Silver Sword (Argyroxiphium), once so abundant is nearly extinct, except in the most rugged and inaccessible localities.

W. D. Alexander
"The Ascent of Mauna Kea, Hawaii"
Hawaiian Gazette, September 20, 1892 (p. 56)
(from Mauna Kea - Kuahiwi Ku Ha‘o i ka Malie by Kepa Maly)



~excerpt from
Mauna Kea – Kuahiwi Ku Ha‘o i ka Malie
A Report on Archival and Historical Documentary Research
Ahupua‘a of Humu‘ula, Ka‘ohe, districts of Hilo and Hamakua, Island of Hawai‘i
By Kepa Maly ©1997 Kepa Maly, Kumu Pono Associates and Native Lands Institute

Once common as low as 6,000 feet, the ‘ahinahina were pushed further up the mountain because of the increasing numbers of grazing animals. By 1920, surviving ‘ahinahina were seen only at higher elevations (10,000 -12,000 feet) on steep cliff faces or rocky shelves, where goats and sheep couldn't go.

From 1936 to 1950, hunting campaigns were carried out to thin the feral populations of cattle and the 40,000 sheep then ravaging the mountain. By 1950 the wild cattle were mostly eliminated and the sheep population had been reduced to only 200 individuals.

Then a pivotal decision was made by a government forester to keep the remaining sheep on the mountain for sport hunting.

It was never planned to eradicate them entirely as the hunting of these animals furnishes excellent sport and is an important form of recreation here on the island of Hawaii.

L. W. Bryan, Associate Forester
“Wild Sheep on Mauna Kea Forest Reserve”
Paradise of the Pacific, 1950

Within a decade the sheep population had expanded again, to 3,500.

In 1971 foresters counted only 100 ‘ahinahina (silversword) plants on Mauna Kea.

At last, in the 1980’s, the state of Hawai’i was ordered by a federal judge to remove all sheep and goats from the mountain. But the damage had already been done. In 1986, the Mauna Kea silversword joined its cousins, the Mauna Loa silversword and the Haleakala silversword, on the endangered species list.

In 1998, there were fewer than 50 ‘ahinahina plants in the wild. Today, the only known naturally occurring population is on cliff faces of Waipahoehoe Gulch.

The remnant populations of ‘ahinahina are undergoing a severe genetic bottleneck, having limited genetic diversity. The native bees and moths needed to cross-pollinate are diminishing. The few remaining plants don't flower at the same time and grow far apart from each other, making cross-pollination almost impossible.

In an attempt to save the silversword from a catastrophic wipeout, specimens have been sent overseas to botanical gardens in New York, Washington, D.C., Chicago, Berlin and San Francisco.

Today’s wildlife biologists continue to search for unknown wild populations of ‘ahinahina, attempting to protect these existing populations from goats and sheep by constructing fences, or exclosures, around them.

But they know that is not enough.



Reintroducing the Silversword
The effort to propagate the ‘ahinahina has had a dismal history. Propagation efforts were begun in the 1960's within a few fenced enclosures on Mauna Kea. But mouflon sheep, which had been introduced to the mountain in 1958 for sport hunting, were released from pens at Kahinahina and Pu’u La’au near the plant propagation areas. The sheep jumped the fences and consumed the precious few young plants.

Over the years, propagated silverswords were outplanted in enclosures near Pu’u Nanaha, Skyline jeep trail, Waipahoehoe gulch and Pohakuloa. But these planted populations, even more limited genetically than the wild populations and still vulnerable to remnant populations of sheep and goats, had only a 34% survival rate.

Beginning in the 1990’s, a concerted effort to save the silversword was begun by a public/private partnership between the Volcano Rare Plant Facility, Hawaii Division of
Forestry and Wildlife, U.S. Fish and Wildlife Service, National Park Service, Biological Resources Division of the U.S. Geological Survey, and the Hawaiian Silversword Foundation.

In 1999, more than 2,500 silverswords were outplanted on Mauna Kea, bringing the total reintroduced population to about 4,000. 1,000 silversword seedlings were also planted on Mauna Loa and Hualalai. Survivorship has exceeded 90 percent at some locations.

The partners have set a long-term goal to propagate and outplant 15,000 silverswords throughout their historical ranges on Mauna Kea, Mauna Loa and Hualalai.

To ensure high genetic diversity in the reintroduced silversword populations, biologists hand-pollinate flowering silverswords in both the greenhouse and the field to produce seeds, in some cases negotiating steep cliffs and rock faces to reach the wild plants.

Read more about propagation efforts: endangered.fws.gov/esb/2000/05-06/22-23.pdf

Although the total population of silverswords has increased during the decades of management, the remnant naturally occurring population has declined.

Every time you’re thinking about working to restore rare plants such as silversword, there’s always the problem of having a really limited genetic set to work with. Some people even claim that, once the population gets down too low, it goes through a bottleneck in which it probably will not recover.

And so every time you find a new undocumented population of silverswords, another steep section of cliff in which a crack in the rocks kept it from the goats or mouflon, that’s when people celebrate because here’s yet another important piece of genetics to be able to add to that pool. And you can try, in those lucky years when both plants are flowering, to cross pollinate and to get much better seeds and to have a richer genetic representation of that plant for the future.

Sam ‘Ohukani’ohi’a Gon III
conservation biologist, 2003


See also

Silversword fact sheet
Endangered Species Bulletin

The Recovery Plan for the Mauna Kea Silversword
U.S. Fish & Wildlife Service
http://www.fws.gov/pacificislands/wesa/mkeaslvrswrdidx.html

WORKING TOGETHER - Partnerships for Endangered Species Recovery
http://www.fws.gov/endangered/partners/poster/silversword.html

Restoring Mauna Kea’s Crown Jewel
View PDF

Arizona Biologists Help Restore Mauna Kea Silversword, One of Hawaii’s Most Critically Endangered Plants
http://www.sciencedaily.com/releases/1998/03/980310080030.htm

University of Hawai’i Botany Department
http://www.botany.hawaii.edu/faculty/carr/ass.htm

Wikipedia
http://en.wikipedia.org/wiki/Silversword

 

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