Nature Corridors
The undeveloped areas that run alongside train tracks from rural to urban areas can be thought of as wild and as nature corridors. When I lived in South-East London, and was making a film about an urban nature reserve in Honor Oak, I was told by a conservationist that wild deer had been spotted locally, having used these nature corridors to make their way deep into the city from the countryside. 
Several years later, we decided to move house and leave the city. I now look for deer along the tracks when travelling to London from our home in East Sussex. As these photos show, I'm yet to be successful. Wildlife photography is not my calling.