“There’s one!” a shout goes up.

Sure enough, one of their quarry flies brazenly overhead: a crow, giving a loud, taunting caw as it passed. This is the Crow Patrol of utility company Kyushu Electric Power, on the hunt for crows whose nests on electric poles have caused a string of blackouts in this city of a half-million on Japan’s southern island of Kyushu.

Blackouts are just one of the problems caused by an explosion in Japan’s population of crows, which have grown so numerous that they seem to compete with humans for space in this crowded nation. Communities are scrambling to find ways to relocate or reduce their crow populations, as ever larger flocks of loud, ominous birds have taken over parks and nature reserves, frightening away residents.

It is a scourge straight out of Hitchcock, and the crows here look and act the part. With wingspans up to a yard and intimidating black beaks and sharp claws, Japan’s crows are bigger, more aggressive and downright scarier than those usually seen in North America.

Attacks, though rare, do happen. Hungry crows have bloodied the faces of children while trying to steal candy from their hands. Crows have even carried away baby prairie dogs and ducklings from Tokyo zoos, city officials said.

While no one knows the precise number of crows in Japan, bird experts and government officials in cities across the nation say populations have increased enormously since the 1990s. Tokyo says the number of crows it has counted in large parks rose to 36,400 in 2001 from 7,000 in the late 1980s, prompting a trapping plan that cut the numbers to 18,200 last year. However, ornithologists say the actual number in Tokyo is closer to 150,000 birds, and that some crows may have moved to different areas to avoid the traps.