On a busy street in Tokyo, you might be surprised to hear the loud call of crows going through garbage. Although crows are abundant throughout Japan, they are particularly noticeable in central Tokyo. They are troublesome because they attack birds, small animals and humans. Scavenging and scattering garbage also cause problems.
The Urban-bird Society of Japan has estimated the number of crows in Tokyo by counting major roosts every five years since 1985. They counted 7,000 in 1985, 10,000 in 1990 and 20,000 in 1995, which shows a dramatic increase.
So, why is the population of crows increasing? Ecological theories state that when food and habitat are secure and there are less predators, animal populations expand. Human activity produces a lot of garbage, which is usually collected in the morning in most areas of Tokyo. What’s more, the garbage is in translucent plastic bags which enable the birds to see the meals. When crows wake up every morning, they can enjoy a feast. In addition, as goshawks and owls don’t live in central Tokyo, the crows have no natural predators. Furthermore many parks in Tokyo which close during the night provide ideal roosting places for them.
The rising crow population causes mounting problems for Tokyo. In the breeding season, crows aggressively defend the territory around their nests, swooping down on people walking below. They peck open garbage bags when they scavenge, scattering the contents, which also annoy people. They sometimes feed on small birds and mammals. At Tokyo Ueno Zoo, you can see that the prairie dog’s enclosure is covered with wires to prevent crow attacks. Starlings and wagtails often roost in huge groups in places where there are a high population of humans to escape the predation of crows. Therefore, their impact on the ecosystem is huge. In addition, last year the nation was terrified when the bird flue virus H5N1 was found in the body of some crows in Kyoto.
Since 2001, every spring the Tokyo government dismantls crow’s nests, disposing of chicks and eggs in the process. They have also killed about 2,000 crows every year. But some researchers believe it is s a waste of time and money as the more birds they remove, the more birds move in from neighboring prefectures.
The key to decreasing the crow population is to control their food. Though it may well be too late, the Tokyo government has finally started to distribute nets to place over garbage bags to keep the birds out. This method, consequently, have proved to be successful but whether people will cover the garbage bags regularly and thoroughly is another question. Furthermore some wards have begun to collect garbage during the night to deny crows access to food, which also works well.
Crows are an important member of the ecosystem, and we should try and live with them harmoniously. They are intelligent birds with lots of ingenuity, I believe, somehow we can get along with them.
Struck, D. “Tokyo’s Winged Bullies” Washington Post Foreign Service Tuesday, June 12, 2001 http://www.crows.net/japnlogs.html [accessed:7/20/2005]
The crom problem in big cities. Yacho, 648,40-41.(Dec.2001)
Hooper, R. “ANIMAL TRACKER Jungle crow” The Japan Times: Feb.10, 2005 http://search.japantimes.co.jp/print/features/enviro2005/fe20050210at.htm [accessed:7/20/2005]