Tokyo (CNN)Wild monkeys have attacked dozens of residents of a city in southwestern Japan in recent weeks, with reports of the animals crawling through house windows and striking from behind, as police step up an unsuccessful search for them.
Japanese city thought they had a rogue wild monkey. As attacks rise, now they fear there's more than one
Since July 8, at least 45 people have been injured by Japanese macaques -- also known as snow monkeys -- in and around Yamaguchi city, according to Yoshitaka Morishige, an official from the Yamaguchi prefectural government's conservation department.
Initially, officials reported that the attacks were the work of one rogue monkey -- but authorities now say they cannot confirm if one or several of the animals were responsible.
The number of confirmed attacks has more than doubled in less than a week. Victims range from toddlers to the elderly, Morishige said.
Those attacked have been scratched on their hands and legs, and bitten on their necks and stomachs, but have not reported any serious injuries, said Masato Saito, an official from the Yamaguchi city hall.
"Recently, we've heard of cases where the monkey has clung onto a person's leg and once that person tries to get them off, they get bitten -- or they've gotten sprung on from behind," he said.
Victims have reported seeing monkeys of different sizes -- "but whether a monkey is small or big changes from person to person as it depends on their perception," Saito said. "Of course, we could work it out if there were a line-up of monkeys, but in this case, we can't say for sure if there are one, two, or several monkeys."
Earlier this month, many of the attacks took place when at least one monkey entered homes and a school through open windows and sliding doors. But now, with residents instructed to keep those entry points shut, more people are being attacked outside, Saito said.
The attacks had prompted police to lay traps, and step up their patrols armed with nets -- but after failing to capture any monkeys, officers were armed with tranquilizer guns Sunday.
Macaques are native to the country and found throughout most of its islands.
"Japanese macaque monkeys have coexisted alongside humans since the Edo period -- Japan is very mountainous and communities live close to mountains where monkeys live, so it is easy for monkeys to enter villages and towns," said Mieko Kiyono, an expert in wildlife management and associate professor at Kobe University.
She added that monkeys live in groups, but young males often leave to live alone for a period of time, meaning the monkey responsible for attacks is most likely to be a male individual.
Yamaguchi officials said such attacks were rare. "This is a very unusual occurrence; they have never come into an urban area like this before and assaulted this many people," Saito said.
But Kiyono said these kinds of human-monkey conflicts have become increasingly common over the years, with research pointing to factors like the resurgence in macaque populations thanks to conservation efforts and decline in their natural habitats.
"In Japan, more and more monkeys are coming into homes and farms, damaging crops," said Kiyono. "Local governments have measures to chase the monkeys away -- for example, they may use fireworks to chase them back into their habitat."
But these measures don't always work -- monkeys could develop hostility toward humans as a result, and may not even return to their mountain habitats. "Monkeys who learn to react against humans will