The WSJ has this great section on geese:
What could possibly cause a majestic V-formation of honkers high overhead on a thousand-mile migration to the Arctic tundra to suddenly drop down and land on a golf course in, say, Greenwich, Conn., defy their instincts, and take up the posh suburban life?
The answer is startling to many Americans: These geese didn’t stop migrating. They never migrated. These geese, say wildlife historians, have virtually nothing to do with wild, migrating flocks. “Resident” geese — the ones most likely to be seen in suburban parks, ponds and soccer fields — are descendants of farmed geese and flocks of “live decoys” once used by professional hunters.
The Fish & Wildlife Service calls them “hybrids … originating in captivity and artificially introduced” around the country. In other words, in most places these geese are a non-native species thriving, like feral cats and kudzu, in an artificial habitat: the welfare-wildlife world of sprawl.