Susanne Sternthal reports from Moscow:

[Animal specialist Andrei] 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.

“They orient themselves in a number of ways,” Neuronov adds. “They figure out where they are by smell, by recognising the name of the station from the recorded announcer’s voice and by time intervals. If, for example, you come every Monday and feed a dog, that dog will know when it’s Monday and the hour to expect you, based on their sense of time intervals from their ­biological clocks.”

The blog English Russia also covered the phenomenon:

Another skill they have is to on the green traffic light. “They don’t react on color, but on the picture they see on the traffic light”, Moscow scientist tells. Also they choose often the last or the first metro car - those are less crowded usually. It’s funny but the ecologists studying Moscow stray dogs also tell the dogs don’t miss a chance to get some play while on their travel in the subway. They are fond of jumping in the train just seconds before the doors shut closed risking their tails be jammed. “They do it for fun ..."