Per lune:

Japan Fights Crowds of Crows
Fanning out in small teams, the men in gray jumpsuits scour the streets and rooftops with binoculars, seeking to guard this city from a growing menace. They look for telltale signs: a torn garbage bag, a pile of twigs atop an electric pole or one of the black, winged culprits themselves.
http://www.nytimes.com/2008/05/07/world/asia/07crows.html?_r=2&oref=slogin