SCOTT SHALAWAY Fall and winter hummingbird facts

Almost every fall I remind readers to take down their hummingbird feeders only after they've seen no hummers for at least a week. It's good advice because shorter days, not food supply, induce ruby-throated hummingbirds to head south.
Over the last five years, however, a curious phenomenon has occurred. Some people forget to take their feeders down, and hummingbirds continue to visit. But they are not ruby-throats; They are usually rufous hummingbirds and occasionally calliope hummingbirds. Both are western species that have no business showing up east of the Great Plains. Yet over the last few months backyard birders in Michigan, Ohio, Pennsylvania, West Virginia, New Jersey, New York, Massachusetts, and even as far north as Maine have spotted vagrant hummers in their back yards. Many have been captured and banded.
Work in progress
A satisfactory explanation for western hummingbirds showing up in the east is still a work in progress, but several factors are at least partly responsible.
First, back-yard birding has never been more popular; every year more eyes observe the happenings in their own backyards. Perhaps these birds have always done this, and we just didn't notice. After all, who looks for hummers in the winter?
Second, back yards landscaped to be hummingbird-friendly and equipped with nectar feeders are hummingbird magnets. Pennsylvania naturalist Scott Weidensaul describes the coastal southeastern states as, & quot;one giant hummingbird garden. & quot;
The third factor, one championed by several hummingbird banders including Weidensaul, is that we may be seeing a, & quot;rapid evolution of new migration routes & quot; by these species. Migration is genetically encoded, and coding mistakes happen. Any birds that head west would die in the Pacific Ocean. But those that head east find conditions that are at least tolerable. And survivable. We now have some recaptures of banded birds that have wandered east and been captured at least twice. If only a few hundred of the thousands of potentially wandering western hummers survive the errant trip, they are likely to repeat it. And birders are increasingly likely to spot some of them. Thanks to the internet, such observations are communicated within minutes of being made.
More notable
Southern banders have been banding hummers along the Gulf Coast for years and their winter work, while interesting, is not surprising because of their southern locations. Fall and winter hummingbird reports from the Midwest and East Coast are far more notable.
Weidensaul explains that these tiny wanderers are hardy critters despite their size. & quot;Rufous hummers nest as far north as Alaska, and calliopes breed at high elevations in the Rocky Mountains, & quot; he says. Snow often covers the ground when rufous hummers return to Alaska in the spring, and it often snows while calliopes are nesting in the mountains. So these birds are not strangers to cold conditions.
Hummers in cold climes respond in a number of ways. At night they enter a torpid condition by slowing their heart, breathing and metabolic rates. At dawn it takes them awhile to waken and warm up. I recall a visit to the higher elevations of a volcano in central Mexico back in the early 1980s when I literally grabbed a torpid white-eared hummingbird from its perch just after dawn. It took the bird about three minutes to warm in my hand and fly off. Hardy hummers prove that size is no indicator of toughness.
What they eat, drink
Winter hummingbirds fuel their metabolism by drinking nectar from late-blooming flowers, sapsucker wells, and feeders when they are available. And they round out their diet with invertebrates just as they do during warmer conditions. Insects called springtails are active even on the surface of snow, and Weidensaul has had reports of winter hummingbirds foraging on the trunks of trees much like woodpeckers. Presumably they find enough dormant insects, spiders and egg cases to meet their nutritional needs.
If you see a hummingbird this winter, especially one that's more brown than green (think rufous) or one that's very small (think calliope), set out a nectar feeder and contact a local nature center or Audubon group. Or send me a note, and I'll pass the information along to someone in your area. For more information about hummingbirds, visit these Web sites: www.hummingbird.org or www.hummingbirds.net.
sshalaway @aol.com.