So when TV footage was aired of police entering the facilities of Aum Shinrikyo in Kamikuishiki, Yamanashi Prefecture, in March 1995 with the precautionary gear, viewers were glued to their television screens.
Like coal miners of old, police used the birds to forewarn them of poisonous gas.
The word canary has a different connotation for people who have left the cult.
In 1995, former followers began publishing a newsletter called "Kanariya-no-Uta," (Poems of Canary) about their recollections of their time with Aum, what attracted them to the cult and updates on the trials of cult founder Chizuo Matsumoto and his lieutenants.
So far, 33 newsletters have been published. The 600-odd copies are distributed to former followers as well as to those who are still loyal to the cult.
The former followers began to congregate as "Kanariya-no-Kai" in June 1995, just weeks after police began widespread raids on cult facilities following the sarin gas attacks on the Tokyo subway system. Taro Takimoto, an attorney from Yamato, Kanagawa Prefecture, was the catalyst for these meetings. He has been helping followers who quit the cult and families whose offspring wanted to cut their ties with Aum Shinrikyo.
Takimoto began counseling Aum followers in 1989 along with Tsutsumi Sakamoto, who that year prosecutors say was murdered by the cult along with his wife and infant son.
Takimoto's dealings with the cult enraged Matsumoto, who retaliated by ordering a sarin gas attack in Kofu in May 1994, where Takimoto was attending a court session on a property dispute involving Aum.
Matsumoto's anger had no limit. Followers planted VX nerve gas on Takimoto's car in September of that year in the hope he would fall sick and die. It didn't work.
Takimoto has interviewed many of Matsumoto's disciples and he said that 80 percent of them now have come to realize that the cult is responsible for the crimes for which cult leaders have been indicted.
Before the arrest of Matsumoto and his lieutenants, followers always told him that the crimes were a conspiracy to destroy the cult and its leader.
Even so, many still believe that Matsumoto has been wrongly accused.
Against this background, former cult members publish the newsletter, which they try to do on a monthly basis.
"To Father and Mother: Please make sure to be there when I am in need and when I need your help. Please be healthy and fit when I turn 30 or 40," wrote a female former follower in one of the newsletters.
Since followers were obliged to donate all their personal assets when joining Aum, many find it difficult to leave the group and start a new life from scratch.
Takimoto noted that many people joined the cult because of problems at home, at school or in society in general.
Former followers contribute articles to the newsletter encouraging cultists to leave.
Takimoto's immediate concern is the probable release next year of Fumihiro Joyu, the eloquent cult spokesman who is serving a three-year prison term for perjury. Joyu is currently awaiting the outcome of an appeal before the Supreme Court.
"We have much to do before Joyu walks out of prison," said Takimoto. He fears Joyu has the power to rebuild the cult's base, although many followers have expressed an open dislike for him.
Joyu would be the first top lieutenant to win his freedom, and that could come as early as the spring of 1999. His release likely would have an enormous impact on those still dedicated to following Matsumoto's teachings, Takimoto said.
However, the attorney cautioned that getting followers to leave the cult is a slow process. He said followers cannot be rushed since they are capable of rejecting the arguments presented to them and in classic fashion return to the clutches of the cult.
Other attorneys who monitor cult activists raise concerns about the followers. Takeshi Ono, who has been working as the secretariat chief of the group of attorneys against Aum, cited the example of a woman follower. She fled from an Aum gymnasium in Yokohama's Naka Ward late last year and took refuge in a nearby shop that sells rice.
A group of followers tracked her down at the shop and explained to the owner that the woman had had a nervous breakdown. In that way, they managed to take her back to the cult.
Ono said whereabouts of dozens of followers are a mystery. Most, if not all, appear to be dead. That is the conclusion they reached after listening to statements by followers and former followers, Ono said.