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Sunday, Nov. 29, 2009
Bearing the brunt
Conflicts between bears and people in Japan are on the rise, and bears are paying a particularly heavy price. How can all this be?
Special to The Japan Times
In a log cabin high on a wooded mountainside in Hiroshima Prefecture, Kazuhiko Maita, 61-year-old director of the nonprofit Institute for Asian Black Bear Research and Preservation, is puzzling over the fate of Japan's black bears.
Outside, the unpainted wood stairs are scored with scratches (four long, one short) where a "moon bear" (so-called because of the white marking on each animal's chest) has climbed up to the porch. Inside, a bear skeleton hulks in a corner of the room beneath photographs Maita has taken during years of field research: bears poking their noses out of winter dens, bears draped sleepily over tree branches, and bears snuffling around for acorns.
Maita has devoted his adult life to Japan's black bears (Ursus thibetanus japonicus). He worked for 20 years in a prefectural wildlife bureau and has since put in another two decades as a conservationist.
Now he watches as the normally reclusive mountain-dwellers teeter on the brink of extinction in much of western Japan and come into increasing conflict with humans nationwide — as in a headline incident this September, when nine people were injured by one animal at a mountaintop bus terminal in Gifu Prefecture.
With sad, tired eyes, Maita stares at his computer screen, where a cascade of graphs he's created from Environment Ministry and prefectural government statistics, and from newspaper reports, illustrate the problem.
Injuries caused by bears: up since 1999 and generally peaking in October. Bears entering residential neighborhoods and buildings: numerous puzzling reports since 2004. The number of bears killed: those killed by sports hunters down, but those killed as pests up — with dramatic peaks in 2004 and 2006.
Theories to explain this potentially terminal turn of events abound, but Maita isn't fully satisfied with any of them.
"(In the 1990s) I felt confident that through various conservation and environmental-education activities — teaching people how to avoid accidents, how to avoid meeting a bear — we had managed to keep the number of people injured per year down to around 20. Then in 2000 the number suddenly shot up. Something is happening here. It's gone beyond our understanding of the situation," says Maita, who throughout the '90s helped popularize catch-and- release rather than killing as a way to deal with bears that entered towns in search of food.
Now, he thinks that weather patterns may play an important role in explaining exactly when and why humans and bears clash.
Maita believes that bears sense drops in atmospheric pressure that often presage rain and strong winds. Consequently, he says, they become more active in order to secure food before the bad weather hits. That could make them more likely to show up in towns to raid fruit trees and other crops, where they easily cross paths with humans. Predicting such behavior through close attention to weather conditions, he says, could help reduce both human injuries and bear deaths.
"On sunny days, activity levels increase — that's true for humans as well. Before it rains, we (traditionally, in farming, hunting or gathering societies) go out to work, and bears go out to search for food. For bears, an increase in activity means an increase in potential aggressiveness (if they encounter people)," he says.
Many animals are sensitive to changes in atmospheric pressure. Migratory birds, for instance, use this sensitivity to avoid bad weather during their flights. Bees are said to hole up in their hives when pressure falls. A 2003 study in the Journal of Fish Biology showed that sharks off the coast of Florida fled to deeper, safer waters before Tropical Storm Gabrielle hit in 2001 — most likely in response to the drop in air pressure that signaled its impending arrival. Regardless of the weather, black bears become particularly active each fall — before retreating to a hollow tree stump, a rock cavity or a hole in the ground in November or December to hibernate until spring warmth gives them a wakeup call. During hibernation, their heart rate and body temperature drop, and through these and other means they are able to survive for months at a time without either eating or drinking.
This is a particularly critical time for females, which generally give birth and start to nurture their offspring in late January or early February while still in hibernation. Scientists think successful reproduction may depend on whether a female bear gets enough to eat in the fall: Although mating occurs in the summer, the fetus does not begin to develop until hibernation begins and may be naturally aborted if the female is undernourished.
Conflict with humans usually rises around September to a peak in October when bears are most intent on finding food, and it tends to happen when they are caught unawares or feel cornered.
Maita wondered if weather might further affect exactly when these incidents occur. To test his hypothesis, he researched newspaper reports on 975 incidents of injuries caused by bears since 1953, then compared that data with weather information from the area where each conflict occurred.
What he found, he says, was that 62 percent of the incidents happened in the three days before a significant drop in atmospheric pressure.
The theory he has developed — summed up in his 2008 book, "Kuma wa Nemurenai" ("The Bears Can't Sleep"; Tokyo Shimbun Shuppan Kyoku) — has not been confirmed by any other scientific studies. Although Maita is one of the country's best-known bear experts after his 40 years' research into them, he neither has a high-level degree nor publishes his work in academic journals. Perhaps predictably, he has received little response to his book from Japan's academics in the field. Many scientists and conservationists, however, agree that bad weather was probably behind the unusually high number of bear-human conflicts that occurred in 2004 — but they point to a decrease in forest food sources rather than to bear psychology.
In the autumn of that year, frequent and strong typhoons tore unripe and inedible acorns from trees in unusual quantities, which many believe was what sent hungry bears into villages afterward in search of other food to fatten up on before their winter hibernation.
Acorns from oak, beech and other broadleaf trees are staples in a bear's diet, and natural cycles in the abundance of acorns are said to impact the frequency of bear appearances (fewer acorns leads to more bears in villages).
Habitat loss has exacerbated this problem, and it may grow worse in the future. In 2004, a study in the Journal of Vegetation Science warned that climate change could cause Japan's beech forests, a key bear habitat, to shrink by 90 percent by the end of the century. Their food supplies could also be impacted by strong tropical cyclones and instances of very heavy rainfall, which are both predicted by the government's Japan Meteorological Agency to be more frequent in the future.
However, Catherine Knight, a New Zealand-based environmental historian who has studied Japan's human-bear conflict extensively, says she is reluctant to accept climate change as an explanation for the increase in bear accidents.
"It's possible that we're seeing more extreme weather that's making the (forest food availability) cycles more severe. But climate change is not that rapid. We have a tendency to latch onto things that are beyond our control. We blame nature for certain things, but we've forgotten our environmental histories," she says.
As far as Japan's black bears go, the key element of that history has been habitat degradation.
"More and more, people are encroaching upon forested areas," says Knight. "Japan is a densely populated country, and so (bears) are going to strike human beings pretty readily to do the things they need to do."
Males typically range over up to 100 sq. km — and females up to 50 sq. km — in search of acorns, insects, leafy plants, honey, bamboo shoots and occasionally carrion or small animals.
Diverse broadleaf forests provide the most abundant feeding and denning locations, but while trees cover 60 percent of Japan, coniferous plantations account for 41 percent of that. In addition, much of the natural mixed forest that remains is fragmented by roads, dams and tourist infrastructure.
Mark Brazil, a biologist (and monthly JT nature columnist) who studies animal behavior, agrees that it's important to think about how changes in human behavior could be causing conflict with bears.
"In the past 20 to 30 years, leisure activities such as hiking and picking mushrooms have become more popular. The number of people entering the forest (to do these things) has increased, and that could explain the increase in injuries," says Brazil, a longtime resident of Hokkaido. In Japan, 25 people have been killed by black bears since 1972, and according to data collected by Maita, all but three fatalities were in forests (the exceptions were in 2004 and 2006). Similar analysis for nondeadly incidents is not yet available.
Much more often, though, it is the bear that dies when the two species come into contact.
From ages past, there has been a tradition of bear-hunting in Japan by matagi (mountain hunters in northern Honshu), but in the 1970s and '80s they were extensively targeted by many others who sought to limit the damage they caused in plantation forests and farm fields. These days most are culled because they are deemed a threat to safety. That is permissible — and common — throughout the country, even in national parks and areas where sports hunting is prohibited.
"Every bear must live in fear of seeing a human," Brazil quips wryly. "If they get sighted and reported, chances are they'll be caught, regardless of if they've done anything. It's like seeing a suspected pickpocket on a corner and shooting them."
Black bears are listed as vulnerable throughout their entire Asian range on the Red List of the Swiss-based International Union for Conservation of Nature (IUCN), with very low populations identified in some countries, including Bangladesh and South Korea. In Japan, they are threatened with local extinction in the Chugoku Mountain Range of western Japan (running 500 km from Hyogo Prefecture in the east to the coast of Yamaguchi Prefecture), on the Kii Peninsula (extending through Mie, Wakayama and Nara prefectures) and the Shimokita Peninsula (Aomori Prefecture), as well as on the island of Shikoku. They do not live in Okinawa or Hokkaido, which is inhabited by brown bears, and are thought to have disappeared from Kyushu decades ago.
Many experts agree that drastic postwar rural depopulation is also a factor in Japan's human-bear conflict, as it has left fewer people to maintain farms and fields. The percentage of people living in towns with populations of less than 5,000 shrank from nearly 50 percent in 1920 to just 1.7 percent in 2000. Small, aging towns on the edge of forests are where much of today's conflict with bears occurs.
"Before the '80s, there was a zone between the villages and the mountains where people cut grass and harvested firewood," Maita explains. "When people stopped managing those areas, the trees grew larger and bears and wild boars were able to live closer to the villages." Orchards full of unpicked fruit and nuts also draw the animals out of the woods.
In this respect, Koji Yamazaki, a council member of the IUCN's Bear Specialist Group, and director of the Japan Bear Network, a national education and information-sharing organization, notes that in northern Honshu bears are not only expanding their range but also, most likely, their numbers.
Yet neither forest degradation nor depopulation have accelerated sufficiently over the past decade to fully explain the recent events: Afforestation with timber crops was largely accomplished by the early '70s, and rural towns were already languishing by the '90s.
That mystery is what sent Maita hunting through stacks of climate data for another explanation for events of the last decade.
But while his theory may shed light on the timing of human-bear clashes, neither it nor other environment-based explanations can fully explain why so many bears are being killed. That's because the relationship between bear accidents and bear culls is not entirely linear.
For example, 2006 — a relatively calm year weatherwise, but a poor year for beechnuts — saw a new high of 145 injuries caused by black bears, marking a 158 percent jump from 2004. Culls, however, leaped to 4,340 — a staggering 218 percent increase over 2004. Both injuries and culls have fallen again over the past two years.
No one knows exactly how many bears live in Japan, but 8,000 to 12,000 is a commonly cited range. That means half of Japan's entire black bear population may have died in the 2006 cull — most without ever harming a human.
"If those numbers are correct, that is really an absolutely unsustainable take from a population," says Brazil. Bears are slow reproducers, with females giving birth to only one or two cubs every other year.
The cause for the killings, according to Maita, was what some call "bearanoia."
"Starting in April, several prefectural governments issued warnings that it would be a bad beechnut year, so villages prepared (for the predicted bear appearances) by setting out bear traps. In 2004 there had been a lot of media, and the city halls were told by local people to work harder on the issue. So they captured bears zealously, and they captured too many," he says.
In other words, as the discussion over what is causing more bears to appear in "human" areas continues, it is ultimately public attitudes and government policy that determine their fate.
The Japan Bear Network's Yamazaki fears that even though bears are not presently endangered in northern Japan, a backlash in public opinion could easily threaten them in the future.
"If we look at whether (their expanding range and population) is a good thing, we see those bears are causing a lot of problems in villages, so the possibility of bears being captured (and killed) also increases. We've got to manage their range. If we don't, in 10 or 20 years it may become acceptable to kill more and more of them," he says, adding that planning and education are desperately needed to halt that negative cycle.
For Maita, gaining a deeper understanding of bear behavior — including how they react to extreme weather and other changes in the environment — is a crucial part of the puzzle that needs to be solved if humans and bears are to continue to coexist in Japan.
"We have to think more about bear psychology, not just data and simulations," he says.
He might well have added that it's time to pay more in-depth attention to humans' attitudes toward bears, too.