The Financial Times has a fascinating article on the lives of stray dogs in Moscow. They quote a wolf biologist who's taken to studying the dogs as dividing them into four categories: guard dogs (relatively domesticated, often "associated" with security guards), beggars (sort of socialized, adept at...begging), wild dogs, and some amorphous category between the beggars and the wild dogs.
But here's the best part:
There is one special sub-group of strays that stands apart from the rest: Moscow’s metro dogs. “The metro dog appeared for the simple reason that it was permitted to enter,” says Andrei Neuronov, an author and specialist in animal behaviour and psychology, who has worked with Vladimir Putin’s black female Labrador retriever, Connie (“a very nice pup”). “This began in the late 1980s during perestroika,” he says. “When more food appeared, people began to live better and feed strays.” The dogs started by riding on overground trams and buses, where supervisors were becoming increasingly thin on the ground.
Neuronov says there are some 500 strays that live in the metro stations, especially during the colder months, but only about 20 have learned how to ride the trains. This happened gradually, first as a way to broaden their territory. Later, it became a way of life. “Why should they go by foot if they can move around by public transport?” he asks.