JUDY JESSOP: More Rufous Hummingbirds Finding Their Way South
The setting is late October high in the North Carolina mountains.
My husband and I sit on the porch of a small cabin perched on the side of Rich Mountain.
It is toward the end of this visit -- and as the days march on -- waves of yellow, gold and rust sweep each mountain from base to peak in a rich kaleidoscope of autumn colors.
However, during this visit not only leaves were changing color. Friends teased me for keeping a hummingbird feeder going -- after all, there were no takers because ruby-throats finish migrating through the mountains by early October.
Late one afternoon, however, a very hungry hummer showed up and spent the last of the fading light tanking up. Early the next morning, she was back, and as I marveled at her appetite I also noticed that this was a hummer of a different color -- her sides and tail a rusty orange, matching some of the foliage in the distance.
Out came the camera and fat lens, within moments I was e-mailing photos to Susan Campbell, our Sandhills' resident hummingbird expert. Her verdict came quickly -- yes, it was too late for ruby-throated hummingbirds, and it appeared from the pictures that I might have a rufous hummingbird partaking of my feeder's nectar.
Rufous hummingbirds nest in the Pacific Northwest, from Idaho, Oregon, Washington up through British Columbia into the southern part of Alaska. These hummers are considered North America's "extremists." Measuring about 3.5 inches in length, they are the only hummingbird that ranges all the way to Alaska.
They nest where the nighttime temperatures often dip well below freezing. With such a harsh climate, it is not surprising that insects, rather than nectar, comprise the largest portion of their diet.
They travel from a summer in the far north way down to Mexico to winter, stroke by stroke, on wings that span not quite four inches and beat from 50 to 60 times per second.
With all that distance to go and so much work to get there, why might a rufous hummingbird be stopping in at a feeder that is located on the other side of North America, in the North Carolina mountains? That seems a bit out of the way.
However, evidence is mounting that an increasing number of rufous hummingbirds end up wintering in the Southeast, instead of Mexico. The birds that are spending their winters with us are not lost -- their migration here just might be programmed in their genes.
Rufous hummingbirds were first observed in the Southeast at the turn of the 20th century. Reports of the birds were sporadic, and those few hummers were considered vagrants (birds that have wandered from their usual migratory route). Between 1909 and 1979, there were records of 68 rufous hummingbirds sighted east of the Mississippi.
In 1988, Bob Sargent and his wife, Martha, hummingbird experts and co-founders of The Hummer/Bird Study Group, began formally observing wintering hummingbirds. They compiled records of rufous hummingbird sightings in five southern states (Alabama, Georgia, Florida, Mississippi, and Tennessee), and when possible, the birds were banded.
With each passing year the number of rufous hummingbirds increased significantly. Researchers, led by Geoffrey E. Hill at Auburn University, joined the Sargents in conducting a study of Southeastern winter hummingbirds between 1990 and 1996.
During those six winters in the five states 1,643 hummingbirds were sighted. During the eight-year period of 1988 to 1996, 358 birds were banded. Based on the banding data, 95 percent of these winter guests were rufous. When you compare the 1990-1996 figures of six winters with the data on hummingbirds for the 70-year period prior to this study, there appears to be quite an increase of rufous hummingbirds wintering in the Southeast.
Young Ones Follow
Some believe the reason for more sightings may be attributed to more hummingbird enthusiasts keeping their feeders up, which attracts the birds.
Though there are certainly more people interested and trying to help track hummers, this does not account for the huge increase in the number of rufous hummers.
There are several species of hummingbirds, such as black-chinned and calliope, which have also been recorded in the Southeast since the turn of the century, yet none of these other species are showing any significant increase in the number of individuals per winter except for the rufous.
Another interesting finding of the study is that the birds are not evenly distributed, but instead clumped in certain areas. In addition, the clumps contain returning, previously banded birds, and hatchling-year or second-year birds.
Not only are adult birds returning, but also young birds are increasingly following the same course. Could these birds be establishing a wintering area in the Southeast? If so, how do they find their way? After all hummingbirds are solitary -- they do not travel in flocks, but each finds its own way.
The possible answers to these questions are intriguing. The Southeastern United States has changed dramatically in the 20th century, from mostly forested to a sprawl of suburbs that over time have developed a patchwork of gardens and flowering shrubs.
In addition, winters are increasingly milder, and many people maintain gardens throughout the year. Meanwhile in Mexico, the traditional wintering territory for rufous hummingbirds, habitat that supports them, has degraded steadily over the century, reducing their numbers to the point that they are considered a species of concern.
Several hypotheses have been offered in explanation for the increase of rufous hummingbirds in the Southeast. An interesting article about the theories can be found on the Internet at: elibrary.unm.edu/sora/Auk/v115n01/p0240-p0245.pdf.
The hypothesis that I find most captivating is that rufous hummers, spending their winters in the Southeast, are successful in surviving winter. As these birds return to breed, their genes, including those for migration orientation, are passed along to their offspring. As a result, with each successful hatching, more rufous hummingbirds are migrating to the Southeast -- ending up where their parents winter.
If this sounds far-fetched, let me assure you scientists have been able to prove that a migrating bird's orienting compass is genetically inherited. It turns out that the Southeast is just about the same number of miles from the breading grounds of these hummers as their traditional winter grounds in Mexico. They are simply orienting to the Southeast rather than due south.
So far this winter in North Carolina alone, there have been more than 80 confirmed reports of hummingbirds. Help us find out more about the winter population of these birds. If you, like me, are curious about these birds, start mixing up that nectar -- one part sugar to four parts water. It lasts much longer in winter, often up to two weeks in cold weather.
If you are fortunate enough to attract a hummingbird, contact Campbell by phone at 949-3207, by e-mail at firstname.lastname@example.org or regular mail at 144 Pine Ridge Drive, Whispering Pines, NC 28327.
Even some of our most public and respected figures are helping. One of these rufous hummingbirds showed up at the governor's house. The flower gardens there still have flowers blooming. Now there are two feeders and that particular rufous is sporting a shiny little leg band.
The hummer that stopped by our door in the mountains was just passing through.
Few rufous birds spend the winter in our mountains, but about 20 percent of those reported for our state are spotted there. Our bird got banded while I watched (snapping picture after picture).
A hatchling of this summer, she was in very good health and still had a little fat reserve to help her on her journey. Measurements of her wings and tail confirmed that she was indeed a rufous hummingbird.
Through the help of others living on Rich Mountain, we maintained that mountain feeder until this girl rufous was ready to move on.
Somewhere among us is a young rufous sporting a band that links her to a journey past our mountain door. I look forward to the possibility of her recapture and news of where she spends her time -- records indicate that three of the banded Moore County rufous have returned for two or more winters to the same yard to feed on small insects and sip at the same feeder.
Our bander, Campbell, just recently told me of two rufous, banded in the Southeast during winter, that were recaptured in the early spring on the eastern slope of the Canadian Rockies -- stopping no doubt at some interested birders' feeders to tank up on their way to start a new family.
It's just a couple of our Southern rufous hummingbirds moseying back to their breeding grounds, passing their genes along so their fledglings will know the way back down to the lovely Southeastern gardens of their winter home.
Judy Jessop can be reached at email@example.com.
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