They're a feature of Marple canals and lakes where children feed them copious amounts of dubious food. As a result, they're quite friendly with humans and don't even worry about well-behaved dogs, although they roost well away from us in secluded fields.
Yes, we're on the flyway between the Canadian north and the wintering grounds. Of course, since the weather here is fairly moderate, many of the illegal aliens have taken up surreptitious year-round residence in many public parks and private stubblefields. They are not particularly welcome in public parks because of their tendency to defecate en masse with no aim.