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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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