Up until a scant few years ago it was believed that the Ruby-throated Hummingbird was the only species to visit our area. But as birders have become more knowledgeable about how to separate the very hard to identify females and young of not only Ruby-throated Hummingbirds but several western species that nest as far north as Alaska, other species are now almost routinely discovered in the fall. Most have been the very similar Rufous Hummingbird, but several other species have occurred as well.
It's known that many species of hummingbirds are highly migratory. Ruby-throated Hummingbirds that nest on Cape Cod probably winter as far south as northern South America, but so far we have not been able to prove it.