For generations, gardeners in the eastern U.S. and southern Canada have had an affinity for Ruby-throated Hummingbirds that visit well-tended plantings all during the growing season. Early April through mid-October, plant enthusiasts delight in their tiny featherballs and sometimes cultivate special flowers that attract even more hummers. Thus, it's understandable that horticulturists lament fall days when the last hummingbird departs in migration and the last flower wilts and dies. Over the past few decades, non-gardeners have been equally entranced by summer hummingbirds, with homeowners enticing the nectar-eaters even to city yards by hanging artificial feeders filled with sugar water. These enthusiasts likewise are saddened by the departure of the final hummer each autumn, but sometimes--either by design or by accident--folks leave up a half-filled feeder well past the last sighting of a ruby-throat. Occasionally, those same people are surprised by the sudden appearance of another hummingbird--often one that doesn't quite resemble their familiar summer visitors. As twice has been the case here at Hilton Pond Center, a closer view usually reveals these winter visitors to be Rufous Hummingbirds--vagrants from the western U.S. that are far more likely to spend colder months in central Mexico.

There's no doubt that some western hummers wandered eastward in late autumn well before the invention of plastic hummingbird feeders. Records of winter sightings in the southeastern United States go back at least until the early 1900s, and in that region through about 1980 there are nearly 100 acceptable reports of probable Rufous Hummingbirds (immature male above right; also see bottom photo). In the past 25 years, such sightings have skyrocketed, and now hundreds of western vagrant hummingbirds are reported every winter from the eastern half of the U.S. Already in 2003 we're aware of Rufous Hummingbird reports from 132 counties or parishes in 25 states east of the Rocky Mountains, and the winter season is just getting started! The big question is whether the number of wintering hummingbirds is increasing or whether folks are just getting better at attracting, observing, and reporting them.

Ruby-throated Hummingbirds, Archilochus colubris--our summer breeders in the eastern U.S.--are not very cold-tolerant, and nearly all of them bail out each autumn to spend the winter in tropical Mexico or Central America. Those few that remain typically occur in coastal states where the maritime effect makes weather less severe. By comparison, Rufous Hummingbirds, Selasphorus rufus--which breed in southern Alaska, western Canada, and the northwestern U.S.--see freezing temperatures upon occasion even on their nesting grounds, so making it through the winter in the eastern U.S. when there's a little snow on the ground probably doesn't seem like an impossible challenge.

Although feeders do bring hummingbirds close enough for folks to see, in most cases the device probably is not essential for a winter hummer's survival--despite the absence of nectar-rich flowers. In the eastern U.S., there may be sufficient sap oozing from mostly dormant tree trunks to provide a carbohydrate fix for some hardy hummers, but many winter birds seem to subsist primarily on tiny insects and spiders that fly or crawl on all but the very coldest days. These mini-invertebrates are chock full of proteins and fats that are just what a winter hummingbird needs to maintain its basal metabolism and fuel its feeding flights. More than once in the Carolina cold we have seen a Rufous Hummingbird fly into clouds of gnats to snap them up one by one, filling its crop and thereby enriching its energy supply.

Although Rufous Hummingbirds are the only vagrants we've banded at Hilton Pond Center, they aren't the only winter species in the East. North Carolina now has ten species on its unofficial list and South Carolina claims eight; several of these have been seen only once, and most arrive after our summer-resident ruby-throats depart. So far we've banded two vagrant hummingbird species elsewhere within York County--the Center's home base--including 11 Rufous (at ten different locations) and a tiny immature male Calliope (at Bethany, about ten miles from York, photo above left). At other sites in South Carolina we've also trapped an immature male Black-chinned Hummingbird (Columbia, photo just above) and the state's first and only Buff-bellied Hummingbird (near Lexington, photo below). Calliopes and Black-chinneds are both western U.S. breeders that winter in Mexico like the Rufous, but the Buff-bellied nests along the warm and sunny Gulf Coast from south Texas to Belize and would seem to have no reason to migrate. What our red-billed Buff-bellied Hummingbird was doing in central South Carolina in early December 2001 is anyone's guess.

Actually, explaining why ANY of our winter vagrant hummers appear hundreds--even thousands--of miles north and east of their historical wintering grounds is pure speculation. We suspect the perceived "increase" in vagrant winter hummingbirds is due to a combination of factors, some of which are mentioned above and reiterated below:

• Hummingbird feeding has become far more popular over the last 10-15 years, and many more people are maintaining feeders.
• More feeders mean more people who "forget" and leave their feeders up past Labor Day, the "traditional" date for taking down hummingbird feeders.
• More people are intentionally leaving a hummingbird feeder up past Labor Day, and maintaining it at least through November.
• All three of the above scenarios mean there are lots more eyes looking out--accidentally or on purpose--for winter hummingbirds, which are more noticeable than summer hummingbirds. Some of those eyes belong to K-12 students and teachers in the U.S. and Canada who are involved with Operation RubyThroat: The Hummingbird Project and its connection with The GLOBE Program.
• The Internet makes a difference. Not only has it made people more aware of the winter hummingbird phenomenon, it is now easier for folks to hear the opinions of hummingbird experts (through chat groups such as "Hummingbird Hobnob") and then to contact them via e-mail without long distance phone charges.
• Initiatives such as the Web sites for Hilton Pond Center and Operation RubyThroat: The Hummingbird Project have alerted people to the scientific value of reporting winter vagrant hummers.
• In southern states, feeders--and late-blooming ornamental plants such as Pineapple Sage, Salvia elegans (right)--may have opened an artificial corridor for wandering western hummer species. This could also be true of the Great Plains, which historically may have been a relatively "food-less" barrier to western hummingbirds trying to fly east in late fall.
• Mild weather during the past several winters may have allowed vagrant hummingbirds to wander further than normal. (Global warming may be playing a role.)
• Habitat destruction in the traditional wintering grounds and/or along migratory paths may be influencing more hummers to wander.
• Hummingbirds are inquisitive creatures; they constantly investigate their environment for new food sources, and it's not unreasonable to think a combination of factors may be enabling (or causing) them to explore distant locales into which they might extend wintering--and even nesting--ranges. After all, in the eastern U.S. there's only one breeding species--the Ruby-throated Hummingbird--while a dozen or more species nest in the West and Southwest.

Regardless of which of these factors--or perhaps others that we haven't considered--might result in increased sightings, it's important that observers report any and all winter hummers for capture and verification. Without in-the-hand measurements by a certified hummingbird bander, it's often not possible to know a vagrant hummingbird's species; without a numbered band on the bird's leg there's no way to know the hummer's origin or its final destination; and, without identification and banding data, our job of understanding what these little birds are doing is far harder, maybe impossible. Thus, we ask you to spread the word about reporting any vagrant hummingbird to RESEARCH so we can travel to band it, or so we can contact another bander closer to where the hummer has been seen. Perhaps through the collective efforts of banders and the public we'll someday find the answer to this week's question at Hilton Pond: "What's with all these winter hummingbirds?"

Hatch-year male Rufous Hummingbird (November 2003)

NOTE: For a complete list of all vagrant hummingbirds we've banded in the Carolinas--plus suggestions for how to maintain a winter feeding station--see Vagrant & Winter Hummingbird Banding; this link includes some information from the account above. For excellent maps that show reports of vagrant hummingbirds, visit Stacy Jon Peterson's Trochilids Web Page.