Crows are considered to be some of the most intelligent birds around and some will be trained to pick up litter in exchange for food, potentially saving the Nordic country millions in street-cleaning efforts.videoA start-up in Sweden has begun recruiting crows in a pilot project to assist in cleaning up the streets of the city of Södertälje in Greater Stockholm.Crows are among the most intelligent animals in Sweden and can learn to pick things up in exchange for food, something that the local company Corvid Cleaning aims to benefit from. In particular, the birds will be taught to pick up...