There's a wonderful story in our local paper about a fellow who was surprised to see what he thought was an ostrich running along the road, he raised the alarm and a policeman wrestled it to the ground until a local farmer brought a trailer along to take it to safety. Turns out that it was a rhea, one of a pair, which escaped from a local smallholding when it was spooked by a visiting chihuahua!
I was convinced i saw one yesterday, going by on the train, along with any number of other animals, pony's and a horse, it was a quick look but it must have been a Rhea, don't they look rather similar.