The group of scientists at Paliku cabin along the eastern rim of Maui’s Haleakala crater in May 2001 could not help but draw stares from the backpackers sharing the campground. After sundown, at a time when most campers would be settling in for an evening of talk-story ’round a rustic, lantern-lit table, Dan Polhemus of the Smithsonian Institution, Jim Liebherr of Cornell University and their crew would spend the next hour beating the bushes, literally, along the eastern edge of Kaupo Gap, looking for critters not seen for more than a century.
During the day, their behavior was just as odd. In addition to beating bushes, they would sift through leaf litter under trees, pulling out whatever insects they might find. Or they might spread sheets under trees and, by applying an insecticide to the trunks, drive out whatever might be sheltering in the bark or mats of moss on the trees. The team was conducting a survey of beetles (Coleoptera) and true bugs (Heteroptera) in dry forest areas that had been fenced to keep out goats and other ungulates. Because of the “aggressive fencing efforts” of Haleakala National Park, says Polhemus, that area is particularly productive for such searches. Among other things, they were also looking for species that had not been seen in Hawai’i for a century or more – so-called hundred-year records.
The efforts paid off. Three specimens (two males and a female) of Blackburnia anomala, an endemic Hawaiian beetle last seen in 1894, were collected in three different locations near Paliku, on the opposite side (southeast) of the crater from where the beetles had been first collected (near Olinda, on the northwestern slope of Haleakala). Although the two sites are distant, the habitat – koa mesic forest and shrubland – is similar.
Polhemus, Liebherr, and the two other members of the team – Curtis Ewing, a graduate student at Cornell, and Raina Kaholoa’a with the U.S. Geological Survey’s Biological Resources Division at Haleakala National Park – wrote up their findings in a report published in the April 2003 edition of Pacific Science.1 The rediscovery of the beetle “in similar, though conserved, habitats suggests that other long-missing koa associates may persist in similar situations on Haleakala,” the scientists write. B. anomala is one of seven species of Blackburnia found in East Maui more than a century ago but not observed in nature since then.
Why might the beetle no longer be found near Olinda? As early as the late 19th century, when Dr. R.C.L. Perkins last found it there, logging and cattle grazing had decimated the koa forest. Perkins had first collected insects near Olinda in 1878, but when he returned in 1894, he wrote, “Here were Koa trees of huge size, but all dead.”
Among other lessons drawn from the rediscovery of B. anomala, the authors write, is that the habitat of this beetle and other “big-head carabid” species is probably more varied than first thought. All were found in areas on or near the ground surface, but, the authors write, these species almost certainly descended from a common ancestor that “exhibited the inherent propensity to climb vegetation.” “If these species retained the ancestral ‘big-head’ propensity to climb vegetation, one would predict that they would be found in similar arboreal situations,” assuming that they were not extinct, the authors write. Thus, the authors suggest, future searches for long-lost species should “focus as much on searching arboreal situations in leeward shrubland habitats as on surveying the ground surface.”
While the rediscovery of this beetle is good news, “not all the news is cheery,” says Liebherr. An O’ahu caribid beetle that “was the most common on O’ahu in the 1800s hasn’t been seen since 1940,” he says.
In addition to looking for “hundred-year records” of beetles and bugs, Polhemus has been assessing the potential rate of extinction in Hawaiian Heteroptera. “Although much recent concern has been voiced regarding rates of insect extinction worldwide,” he says, “comparatively little solid data exists with which to assess actual rates of loss or endangerment over time.” But endemic Hawaiian bugs, studied since the 1830s, “provide a 170-year baseline against which to assess the effects of environmental perturbations.” Some 370 species of true bugs are found in Hawai’i, and Polhemus has begun to search for those species not seen in more than 50 years.
“After two years of effort,” Polhemus told Environment Hawai’i, all but 38 have been rediscovered, “giving an upper bound of 10 percent species loss since 1830.” It’s a rate that, he adds, that while significant, is less than half that seen in the endemic Hawaiian plants, land snails, or birds over the same period. Overall, he says, this suggests that “extinction rates in Hawaiian Heteroptera (and probably Hawaiian insects in general) are lower than those for other groups.”
But there may yet be an accelerating crisis in dry forest extinctions, Polhemus adds, “where many Heteroptera species are confined to small stands of rare plants or aging individual trees.” “Without aggressive restoration ecology efforts,” he continues, “it is likely that this dry forest component will dominate endemic Hawaiian Heteroptera taxon losses in the coming decades.”
Nor should the losses that occurred after the earliest humans arrived be overlooked, says Polhemus. “Significant losses occurred in lowland coastal ecosystems, such as the now-vanished loulu palm savannahs, although the magnitude of such losses is impossible to estimate.”
Finally, the search to rediscover missing species has turned up a few new species as well. Polhemus and his colleagues have come upon as many as 50 species of Hawaiian bugs never seen previously.
- 1. “Rediscovery of Blackburnia anomala (Coleoptera: Carabidae), in East Maui, Hawai`i, after a 107-Year Hiatus,” Pacific Science (2003), vol. 57, no. 2: 161-166.
— Patricia Tummons
Volume 14, Number 1 July 2003
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