This also, in the Telegraph. Evidently, the German squirrels have emboldened the crows. What's really alarming is this:

Officials such as Volker Dumann, a spokesman for Hamburg's Environment Office, said there was little his authority could do because EU legislation permitted the shooting of crows only under exceptional circumstances. "The EU guidelines only allow crows to be shot if they pose a serious threat to citizens' well being," he said. "For that to happen, the number of attacks would have to increase rapidly."

The birds have certainly posed a threat to some citizens' well-being. Maybe they should carry umbrellas modeled on the Avengers.