"Why ?, its not for an easier living, as i watch some of them scratching hard to exhist,...." (Sirocco)
for many it is an easier living, town foxes don't have to catch their dinner it's just taken from the nearest bin outside the takaway or fed to them by a 'kindly animal lover'. For peregrines there's an abundance of starlings and feral pidgeons in our cities. The urban environment is a patchwork of habitats that suit many native and non native creatures against the countrysides, often, sterile monocultures.