The Savannah sparrow (Passerculus sandwichensis) is a small American sparrow. It is the only widely accepted member of the genus Passerculus. Comparison of mtDNA NADH dehydrogenase subunit 2 and 3 sequences indicates that the Ipswich sparrow, formerly usually considered a valid species (as Passerculus princeps), is a well-marked subspecies of the Savannah sparrow, whereas the southwestern large-billed sparrow should be recognized as a distinct species (Passerculus rostratus).
The common name comes from Savannah, Georgia, where one of the first specimens of this bird was collected.
This passerine bird breeds in Alaska, Canada, northern, central and Pacific coastal United States, Mexico and Guatemala. The Pacific and Mexican breeders are resident, but other populations are migratory, wintering from the southern United States across Central America and the Caribbean to northern South America. It is a very rare vagrant to western Europe. source