The Eurasian Ring Neck Dove is a peaceful dove. They do tend to travel in pairs or even in groups of even numbers. I am assuming they are in pairs of the birds. The variety invaded this country from across the waters first being spotted in Florida. I don't know the specific dates but it didn't take it long to spread throughout this country. I believe I have viewed photos of ring necks in Canada and in England. Hearsay from others on the blogs say that this bird is has crowded out a lot of our smaller morning doves. I don't know the stats on that but I do still see the smaller doves at my feeders and in my yard. I know when these birds are at the feeder as they are a large bird.
On a side note, these birds have good eyesight as they were watching me from the window as I stood in the dining room looking out. I can play "statue" and they do get use to my watching them.