http://www.popsci.com/science/article/2010-01/moscows-stray-dogs-evolving-greater-intelligence-wolf-characteristics-and-mastery-subway

The guard dogs follow around, and receive food from, the security personnel at Moscow's many fenced in sites. They think the guards are their masters, and serve as semi-feral assistants. The scavengers roam the city eating garbage. The wild dogs are the most wolf-like, hunting mice, rats, and cats under the cover of night.

But beggar dogs have evolved the most specialized behavior. Relying on scraps of food from commuters, the beggar dogs can not only recognize which humans are most likely to give them something to eat, but have evolved to ride the subway. Using scents, and the ability to recognize the train conductor's names for different stops, they incorporate many stations into their territories.

http://www.ft.com/cms/s/2/628a8500-ff1c-11de-a677-00144feab49a.html