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I am not sure where it began, but the notion that we had to take down our hummingbird feeders in the fall so as to discourage birds from remaining past their normal time of departure has been around a long time. My guess is that this piece of suburban folklore has arisen on two false premises: 1) that the feeder serves as a primary source of nutrients and 2) the observation of a few late season hummingbirds at feeders. The latter subsequently, and I suggest erroneously, interpreted as individuals that lingered, having failed to migrate. Thus we did harm, subjecting the bird to severe weather that it might otherwise not be exposed to normally. Consequently, we would want to 'correct' the situation by taking the bird into our care. Such was the case with Wisconsin's first Anna's Hummingbird (Calypte anna) at a feeder since late one August. Upon removing the feeder in early November, "it quickly became evident that the hummingbird was totally dependent upon the feeder and would die if not fed, so the feeder was returned" (Tessen 1991). On 3 December, 1990, the bird was captured and moved to the tropical dome of Milwaukee's Mitchell Park Conservatory (Robbins 1991). Similar pre-emptive measures have involved the Rufous Hummingbird Selasphorus rufus twice recently in Ohio( pers. comm. Orendorff 1993, and Tom Kemp 1994), Ontario (Weir 1986), and Pennsylvannia (Hall 1992). Our motives are no doubt well-intentioned. Of the few instances where hummingbirds have been captured and housed in an artificial enclosure, there are few instances where this involved a licensed rehabilitator. However, the increase in detection of several species throughout the midwest and east coast and the attention brought by authors in the popular press (e.g. A. Heidecamp's, Hummingbird in My House: The Story of Squeak) may see more of the above decisions referred to the rehabilitator. The past couple of decades have seen such an increase in winter hummingbird activity throughout the midwest and the southeast US that I have come to view the appearance of late season hummingbirds in a different light. Records had accumulated to such a degree by Conway and Drennan's review (1979) as to indicate that for the Rufous Hummingbird the southeast US, in particular the Gulf states, was increasingly a favorable wintering site. This represents an extension northeast of their normal wintering in Mexico, inclusive of the Florida Panhandle and a smattering of sites north to the Alabama/Tennessee border Calder (1993). Today, largely through the efforts of hummingbird banders like Nancy Newfield in Louisiana and Bob Sargent in Alabama, we understand that not just Rufous Hummingbirds but a half dozen other species of "western hummers" now frequent the southeast in winter on a regular basis. Coincidentally, we know that our "eastern hummingbird", the Ruby-throated Hummingbird Archilochus colubris, with rare exception (southernmost Texas and elsewhere along the Gulf coast), migrates completely out of the country. I am not aware of any evidence to suggest that hummingbirds rely on a feeder for their survival, save for those extreme instances of prolonged freezes. Generally it is thought that a feeder is only supplemental to a hummingbird's diet (Calder 1993). I understand how difficult that view may seem late in the fall especially against a snowy background. However, hummingbirds do consume insects much as the familiar 5.5 gram Golden-crowned Kinglet which winters throughout the midwest and into Canada. Hummers also can experience torpor, a brief metabolic shutdown, so as to conserve energy. That is not to say that any hummingbird may survive persistent harsh weather. The Ruby-throated Hummingbird begins its southward journey by the last few days of July and most adults are gone from Ohio by mid-August. Immatures follow in earnest usually peaking about the 2nd week of September. Late Ruby-throats do routinely appear through mid-October but surprisingly few have been reported any later. Indeed none have been documented in Ohio after mid-October (Peterjohn 1989) and it is quite possible that claims of this species, well into November or December actually represented the very similar Black-chinned Hummingbird Archilochus alexandri or another western species. This apparently holds true of Indiana (Mumford and Keller 1984), Michigan (Adams 1991), and Illinois (Bohlen 1989), although Wisconsin (Robbins 1991) reports a sight record from December, a bird having survived "snowstorms and subzero cold". During an especially mild winter a Ruby-throated Hummngbird overwintered as far north as Wilmington NC (LeGrand 1986). However, looking at the documented record across the mid-west, it appears observers may simply have been too quick to assume that a late season hummingbird was the same species they had seen all summer. The Rufous Hummingbird, in contrast to the Ruby-throat, is a very hardy species. Just why we have seen its range expansion into the southeast remains open to speculation. Global warming . . . ?, more likely a growing human population and coincident growth in feeding stations, and/or the surge in exotic flower plantings through the area. Whatever it is, it certainly helps, on the part of the bird, to be able to survive freezing temperatures ( Calder 1993; pers. comm. Sargent 1995). The winter of 94-95 saw a Rufous Hummingbird surviving at least to the end of January in Missouri. Nor was it alone, Anna's Hummingbirds have been wintering in both Missouri and Tennessee the same season. Further south one party banded about 70 hummingbirds of several species the same winter (pers. comm. Sargent). Just as there is a distinct migration period for the Ruby-throat, there is also one developing for those few Rufous Hummingbirds on their way to the southeast U.S. for the winter (Fazio 1991). Throughout the midwest we can expect adults any time from mid-July to November, although most appear in August. We can expect immatures from late August to November with most first appearing in October. Many are likely to hang around a feeder and may regularly do so well into December, expressing the normal habit of the species to defend a territory in migration (Gass 1978). The sudden departure of one of these lingering individuals may be construed as death of the individual or that it has finally moved on. I grant that we can |
rarely be sure. Most late season hummingbirds, for all their cold-hardiness, are not seen much past late December to mid-January in the upper midwest. Rather than succumbing to the cold as is often asssumed, these individuals may respond with facultative migration. One enterprising Selasphorus in Surrey, Maine, apparently moved into a greenhouse of its own volition remaining at least through January (Duncan 1990). Many, however, may move on to the Gulf coast or in mild seasons the Carolinas. Evidence of this pattern is slowly developing through the banding efforts of the Newfields, Sargents, and others. An Allen's Hummingbird Selasphorus sasin, from late October to early January in Chattanooga TN where banded, was later captured that winter in Cartersville GA (Hall 1994). Most telling, is the story of one remarkable female Rufous Hummingbird. Banded as an adult in December 1989 on the wintering grounds of Pensacola FL, she was subsequently captured 2 Feb 1992 in Bay Minette AL, and again in Springfield MO 26 October 1993 (Brock 1994). Attraction of any bird to a feeder may increase its risk of mortality ( e.g. disease, depredation ). Do hummingbirds attracted to feeders succumb to the elements? - certainly. A Rufous Hummingbird was found frozen one late January day in Arkansas (James and Neal 1986). Such are the perils of overwintering attempts at the thermal limits for any species. Those limits were no more clearly defined for wintering hummingbirds along the Gulf Coast by the record-breaking freeze of December 1989. Temperatures dipped to 11 F in coastal Alabama and Louisiana, remaining below freezing for 80 hrs straight (Muth 1990). Muth's summation say's it all : ". . . in a winter like the one past . . . disaster strikes. A few made it through because of prodigious human effort: round-the-clock feeder warming, makeshift heated feeders, and, in some cases, because birds were lured into greenhouses, temporary enclosures, garages, or even homes. Absolutely astonishing, however,were the few birds that seemed to survive without obvious human intervention." Even in the face of 'disaster', I find no convincing argument for such intervention. Do we attempt to house every bird that would be susceptible to the elements? Why do we not capture all lingering feeder species? What of the Cape May Warblers Dendroica tigrina and Baltimore Orioles Icterus galbula found every year attempting to overwinter further north than usual. I suspect we are biased toward the plight of the hummingbird less for biological reasons and more because of the perceived fragility of these tiny creatures. Tiny creatures with life spans generally longer than that of many songbirds 3 or 4 times their mass, and which undergo significant migrations; in the case of the Rufous Hummingbird, the longest known avian migration, as measured in body lengths (Calder 1993). It is not as though taking a bird into our care is without risk. A Rufous Hummingbird at a feeder in Bemidji MN from late August died 3 days after its capture October 22nd (Tessen 1979). Would this bird have left of its own accord in time? More recently a Calliope Hummingbird (Stellula calliope) was captured in Minnesota with the intent of sending it to Louisiana - it died shortly after capture (pers. comm. Schumacher). Should you find yourself with a report of a hummingbird that "needs rescuing" first find out what kind of hummingbird it is. Consider that the individual may simply be stocking up for the journey ahead. With respect to Rufous Hummingbirds, if a live individual is brought to you, a weight much below 3.5 indicates the bird may be in stress, having burned up some muscle tissue (expected if the bird has only recently arrived on the scene from a migratory flight). If above 3.5 grams it is likely putting on lipid weight, refueling for further adventures (Carpenter et al. 1993). If the bird is otherwise healthy, I recommend you resist the urge to get the bird off the sauce and into rehab. The question of necessity aside, rehabilitators should ask their state agency of the legality of handling an otherwise healthy bird. There is no certainty that a late season hummingbird will survive severe energetic demands, no more or less so than another feeder species. There is also no certainty that capture of the animal will lead to a beneficial outcome. Final notes: I focused on the Rufous Hummingbird as this is the most likely hummingbird species in the midwest after mid-October. There are only about 11 records of this species for Ohio, however, all from the past 10 years. Indeed, it now seems to be a rare but annual autumn visitor, which I can only imagine will become more prevalent were more birdwatchers to make a point of leaving up hummingbird feeders into November. An avante garde suggestion? Not really, both the Missouri Dept. of Conservation and the Texas Parks and Wildlife Dept. (Isham 1995) have engaged in 'backyard hummingbird diversity' studies wherein they urge enthusiasts to leave their hummingbird feeders up. In Texas this is a year-round activity, while in Missouri J.D. Wilson (MDC, state ornithologist) suggests taking down feeders January 1st. Feederwatchers in Ohio or other midwestern states engaged in such a survey might experiment with a mid-December cut off . Although Missouri and Texas are likely closer to the main flyway for western hummers, I suspect that more feeders and more people watching for them elsewhere would reveal additional species for the midwest and better elucidate the timing of their migrations. In Tennessee, J. McLaughlin attributes such an awareness to the increase in the detection of western species in that state (BIRDCHAT internet posting Jan 6 1995). These might include Black-chinned Hummingbird, Anna's Hummingbird, Allen's Hummingbird and Broad-tailed Hummingbird (Selasphorus platycercus); all recorded now in the midwest. All of which present some considerable identification challenges so you will want a copy of the National Geographic Society's field guide and Kaufman's (1990) "Advanced Birding" on hand. |
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