During a drone delivery trial in March in Shiso, Hyogo Prefecture, a 3.6-kilogram device carrying a bento boxed lunch was surrounded by birds that appeared to be black kites. The pilot took evasive action to avoid a collision and the birds eventually dispersed, but other drones have not been so lucky.
With the use of drones to transport goods expected to increase in the future, especially in rural areas and on remote islands, reports of bird attacks have triggered calls for the government to raise drone pilots' awareness of the dangers involved.
It is thought that attacking birds confuse drones for potential enemies, and in some cases, they have caused unmanned flying devices to crash during midair skirmishes.
"I never thought birds would target a drone," said a shocked prefectural official who was observing the trial in Shiso. "Luckily it didn't collide with them."
According to experts, crows and black kites have a habit of attacking things they perceive as threats in the vicinity of their nests.
According to the Land, Infrastructure, Transport and Tourism Ministry, five drone crashes linked to birds have been reported since 2017, when the ministry received the first report of such an accident. In the first-reported crash, a drone fell into the sea after colliding with birds in Fukui Prefecture.
The actual number of crashes linked to birds is believed to be higher because reports are not mandatory unless accidents involve damage to people or buildings.
For example, when a drone operated by Honey Bee Works Co. crashed after a bird attack, the Hiroshima-based aerial photography firm did not report the accident, as no one was injured.
When drones are used, there is also a risk of out-of-control devices falling and hitting people on the ground. In February 2017, a drone became uncontrollable while taking aerial photos and crashed at a construction site in Fujisawa, Kanagawa Prefecture, leaving a worker with serious facial injuries.
Since June, the owners of drones weighing 100 grams or more have been required to register their devices with the central government. As of the end of July, about 287,000 drones had been registered, according to the transport ministry.
Drones are currently utilized for various purposes, such as inspecting bridges and steel towers, and spraying agricultural chemicals. In the mountain municipality of Ina in Nagano Prefecture, drones are used to transport groceries from the supermarket to a community center.
According to a survey by Impress Corp.'s research institute, the drone market was estimated to be worth 230.8 billion yen in fiscal 2021, a more than sixfold increase compared to five years before, when it was worth 35.3 billion yen.
The ministry plans to introduce drone licenses by the end of March next year and lift a restriction on flights in which the drones are not visible to pilots. Currently, such flights are only allowed in mountainous areas, but they will be permitted in residential areas.
The problem of bird attacks is likely to increase as drones become more widespread.
While warning shots are used to scare off birds at airports as a safety measure, efforts to ensure the safety of drone flights are lacking.
"If the number of accidents increases, we will consider how to deal with them," a ministry official said.
In a training program offered by the Japan Drone Association (JDA), participants are shown footage of a drone being attacked by birds and are advised to evade such accidents by rapidly increasing altitude when birds approach.
"There have probably been many near-misses in the past," said the JDA's Junichi Iinuma. "I hope the government informs people about the risks of bird attacks when it issues certifications to pilots."
According to Keisuke Ueda, president of the Wild Bird Society of Japan, increasing drone altitude is the best way to avoid attacks because birds typically dive from higher altitudes when they strike targets.
Ueda, a professor emeritus at Rikkyo University, said drone pilots should also understand something about the ecology of the birds.
"The breeding season for crows is from March to June, and for raptors, it's from December to early summer," he said. "It is also important to carefully set flight routes during these periods, for example, avoiding forested areas where nests are located."
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