Wekiu
Mauna Kea, kuahiwi ku ha’o i ka malie. Mauna Kea, standing alone in the calm.
‘Olelo No’eau Hawaiian Proverbs & Poetical Sayings, by Mary Kawena Pukui (1983)
Mauna Kea is prominent in Hawaiian cultural and natural history. When measured from its base on the ocean floor to the tip of the summit cone, Pu’u Wekiu, it is the tallest mountain in the world at over 29,500 feet. Its distinct profile can be attributed to the dozens of volcanic eruptions along its slopes. Celebrated cultural features include a network of ancient trails linking lowland habitation sites with the summit, home of the snow goddess, Poli’ahu; Lake Waiau, carved by glaciers; and Keanakako’i, a traditional Hawaiian adze quarry in the Mauna Kea Ice Age Natural Area Reserve. Over the years, concerned individuals and organizations have taken action to protect its manane-naio forest, the endangered palila bird, and more recently, the summit itself.
Mauna Kea also is the only place in the world where the wekiu bug (Nysius Wekiuicola) can be found. The bug, whose Hawaiian name means summit, was unknown until discovered in 1979 by Francis G. Howarth, Steven Lee Montgomery, and William P. Mull. This unique insect lives at elevations above 11,000 feet and is a member of the aeolian alpine lava natural community. This community is sparsely vegetated with lichen, algae, and moss and supported by organic matter blown up the mountain from lower elevations. A wolf spider, centipede, and flightless moth are among the native species that share this habitat with the wekiu.
The wekiu lives in spaces between cinders and other tephra (volcanic fire-broken rock) where it rests, hides, and migrates without being exposed to the surface. It has been reported from volcanic cones, including floors, inner and outer slopes, and ridges; crevices associated with lava flows; and talus slopes. Black with pale reddish-brown median bars, adult wekiu are small -about the same size as a grain of rice.
As with almost all other endemic Hawaiian species, the most fascinating aspect of the wekiu is its natural history. The wekiu has evolved to occupy a predator-scavenger niche on the summit, preying on dead insects and birds blown up the mountain from lower elevations. It uses snow to its advantage by feeding on organic matter kept fresh or immobilized by the cold. Permanent ice exists just a few feet below the surface, and antifreeze properties in the wekiu’s blood allow it to inhabit this harsh alpine zone.
The family of Lygaeidae (seed bugs), which includes the wekiu, contains few predators. In Hawai’i, the genus Nysius has radiated into over 26 species that eat the seeds of native plants, with the exception of the wekiu and its close relative and Mauna Loa counterpart, Nysius aa. The wekiu may be the most unusual of the 106 Nysius species worldwide.
In May 2003, KAHEA: The Hawaiian-Environmental Alliance petitioned the Secretary of the Interior to list the wekiu as an endangered species with critical habitat designation.1 Habitat loss and degradation, human activities, and introduced species threaten the wekiu. The wekiu is currently designated by the U.S. Fish and Wildlife Service as a candidate for listing2 and, the service says, the wekiu is one of its highest-priority species for listing.
No one knows how many wekiu occur on the mountain or what their reproductive potential is. Previous surveys of selected habitat were conducted in 1982, 1997, 2001, and 2002. The number of bugs captured in the 1982 sampling effort was higher than the numbers captured in 1997 and 2002. However, biologists note that population trends cannot be made based on the 1982, 1997, and 2002 data because of varying methodologies and other factors. Any decline that might have occurred in the population as a whole, or in localized areas, may have been the result of climate change, a possible long-term downward trend in winter snowpack depth and persistence, introduction of predatory alien arthropods, habitat disturbance from telescope construction, recreational impacts, vehicle impacts, and the possible presence of environmental contaminants from human activities.
The species’ rarity is demonstrated by the fact that only 47 wekiu were trapped and an additional five were observed despite 398 total trap-days of sampling effort in 2002. According to the service, since the 1960s, when the first modern road to the summit was bulldozed, approximately 62 acres of potential wekiu habitat have been lost to astronomy development. More than two-thirds of the wekiu bug’s potential range is currently unprotected from future development.
The Mauna Kea Science Reserve, administered by the University of Hawai’i Institute for Astronomy, occupies approximately 11,200 acres on the summit and includes nearly all the wekiu’s known habitat. The proposed outrigger telescopes at the W. M. Keck Observatory, associated infrastructure, and human activities on Pu’u Hau’oki pose the latest threat to the wekiu. If the telescopes are approved, the California Association for Research in Astronomy proposes to try to restore 6,200 square feet on the crater floor (15.5 percent of the crater floor). This dubious proposal is unproven and focuses on only a small portion of the wekiu’s range.
The service is preparing a Candidate Conservation Agreement with the Institute for Astronomy and the state for the wekiu. A draft has not been finalized or released to the public for review, but it is highly unlikely that such a voluntary agreement will lead to the recovery of the species or its habitat.
The constant human traffic to the Mauna Kea summit associated with astronomy-related activities, tourism, and recreation increases the likelihood that harmful alien species will be introduced to the wekiu’s habitat. Controlling such species will not be possible without threatening the wekiu and other native invertebrates. The wekiu must already compete with at least one introduced sheetweb spider that has become established on the summit. Of even greater concern is the establishment of the introduced spider Meriola arcifera, native to South America. This spider, which is not a web-builder, hunts for its prey on the ground. It is so common in the Mauna Kea Science Reserve that some fear it may already be reducing populations of the smaller native arthropods, including the wekiu.
The unique wekiu and its habitat on Mauna Kea must not be sacrificed in the name of scientific and economic pursuit. Mitigation measures – promised in exchange for land development and increased human activities – should be scrutinized carefully by independent experts. Given the state’s history of land abuse on the mountain and efforts by the current administration to commercialize Natural Area Reserves and other public-trust resources, concerned individuals must continue their involvement in Mauna Kea matters.
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- 1. Petitioned critical habitat includes the Mauna Kea summit above 11,700 feet, including all locations from which the wekiu has been observed or reported, and any unoccupied habitat deemed necessary to recover the species.
- 2. Candidate species are those for which the service has sufficient biological information to indicate that listing the species as threatened or endangered may be warranted
— Marjorie Ziegler
Volume 14, Number 2 August 2003