The Savannah sparrow (Passerculus sandwichensis) name comes from Savannah, Georgia, where one of the first specimens of this bird was collected by ornithologist Alexander Wilson. One of the most numerous songbirds in North America, it is a very variable species, with numerous subspecies, several of which have been split as separate species at various times. The different forms vary principally in the darkness of the plumage. Savannah Sparrows frequently return each year to the area where they hatched. This is called natal philopatry.