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In Japan, Extinction Threatens an Ancient Empire of Industrious Insects

Biology: On the island of Hokkaido, the world's largest ant colony once housed more than 300 million of the creatures, but they are being decimated by development.

August 22, 1999|GINNY PARKER | ASSOCIATED PRESS

ISHIKARI, Japan — A man in a tweed blazer and a white sun hat walks slowly through a patch of sea grass on the coast of northern Japan, searching.

A truck rumbles down the highway toward a cluster of cranes in the distance, but he doesn't look up. He bends down when he finds what he was looking for, a small hole in a pile of sand--the entryway to the largest colony of ants ever found on earth.

For Prof. Seigo Higashi, this is not just an anthill, it's a life's work. For 28 years, he has studied, counted and even lived among the hundreds of millions of Japanese red wood ants that dwell on this strip of shoreline.

Higashi has observed every facet of their life cycle, from their eating habits to their mating rituals. Now 50, he began studying the ant colony as a graduate student in his early 20s. Today he is watching their ancient empire die.

"There used to be a whole lot of these," he said, kneeling to pick up one of the orange-brown bugs between his thumb and forefinger. "Now so many have disappeared."

In the early 1970s, Higashi was part of a Hokkaido University team that made a startling discovery.

Studying ants on the coastal grasslands of Japan's northern island of Hokkaido, they found a cluster of nests linked in a large network, a supercolony.

At the time of its discovery, the Hokkaido colony included an estimated 45,000 nests and stretched nearly 12.4 miles along the shore of the Japan Sea.

The complex housed an estimated 307 million Japanese red wood ants, including some 306 million workers and about 1.1 million queens.

The scale was--and still is--unprecedented.

"As a species, this ant isn't rare or particularly unusual," said Higashi, who took the first head count here in 1971. "As a supercolony, though, it's really something."

There are only two known ant supercolonies in the world. The other, smaller one is in the Swiss Jura mountains.

A typical ant colony is composed mostly of one or more egg-laying queens and infertile females, or workers, who tend the young, expand the nest and defend the colony. For a short period once a year, the colony produces males and fertile females. These ants leave the nest in a "nuptial flight" to mate and start new colonies.

Generally, individuals from different nests will fight each other to the death, even if they're the same kind of ant.

But for reasons scientists don't fully understand, the ants here and in Switzerland--both of the Formica genus--have been able to build supercolonies connected by trails or tunnels through which workers can travel freely.

The Hokkaido supercolony is populated by a relatively common species, the Japanese red wood ant. It can be found in Japan, Siberia, China, Taiwan and the Korean Peninsula.

But only in Hokkaido is it known to have constructed a supercolony.

Higashi said he thinks the colony could have been started as long as 1,000 years ago near the mouth of the Ishikari River, about nine miles north of Sapporo, Hokkaido's largest city.

Since the colony wasn't discovered until this century, Higashi said, scientists aren't 100% certain of its age.

There is one thing he does know: It takes a lot longer to build a supercolony than to destroy one.

Construction of the new port on Ishikari Bay began in 1973. Port facilities were constructed, roads were built, warehouses, cement silos and industrial-sized freezers were installed--all on top of the ant megalopolis.

Within a decade, the development project covered about 30% of the area formerly occupied by the supercolony. Today, Higashi estimates, it has reduced the number of ants living there by more than half.

"If only we'd found the supercolony sooner," he said. "Maybe then we could have done something to save it."

The Japanese wood ant defends itself easily. Touch the outside of one of their mounds, and ants will rush up your arm and deliver a smarting bite.

But it is extremely sensitive to change. Vibrations caused by jackhammers and trucks can easily wipe out entire nests. Roads, waterways and buildings can restrict the ants' ability to move between the nests of the colony.

Still, the Hokkaido government and authorities in Tokyo say protecting the colony is not of particular concern.

"This species of ant is not seen as endangered," said Takanori Higuchi, a spokesman for the Environment Agency in Tokyo. "There's nothing we can do."

So the construction continues.

Higashi rarely gets out to see his ants anymore.

He has taken up studying several other types of ants and has left the research on the supercolony to his graduate students.

"It's a pity," said Daniel Cherix, a professor at the University of Lausanne in Switzerland who has studied both the Swiss and the Japanese supercolonies.

In much of Europe, Cherix said, the Formica ant nests are protected. But he admitted that when economics is a factor, protection "is really kind of hard."

Higashi, however, thinks the real problem is that ants are ants. Why would anyone want to protect bugs?

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