by Bob Sargent
(exerpted from Netlines, the historic newsletter chronicling what we were learing in the early days of hummbanding)
This is the first installment in a series on hummingbirds that we have encountered in the Southeastern United States as part of our study of this wonderful family of birds. We will be giving some opinions based on our work and observation both in the hand and in the field. As with any scientific endeavor, the truth is constantly revealing itself to those that systematically search for it. We are engaged in that search, thanks to the generosity of our members. What you will read here will surely be refined and updated in the future by other qualified researchers, including current members of our staff.
To tell you about Rufous hummingbirds is a labor of love. Starting from the time that Martha Gail and I would regularly drive 600 or 700 miles to investigate a single reported ‘brownish’ hummer in the late 80’s, till now where we get 500 such reports annually, it never grows old. There simply is not enough time to check out all of the reports, but we try. I remember the first Rufous we captured and banded, an adult male in Mountain Brook, Alabama, in August 1987. The Banding Laboratory in Laurel, Maryland, wanted to know how we could have captured and banded a bird in an area so completely out of range. They wanted measurements and weight and photographs. We had all of that and more. I also remember the hordes of people that visited the home of Ellen Cunningham to see this very special bird. Although we certainly find Rufous to be a regular winter resident of the Southeast each year, they are no less special. It seems appropriate that one of our first Rufous of the ‘winter season’ of 1995/96 was at the new residence of now Life Member Ellen Cunningham.
Rufous hummingbird is probably the most hardy of all the hummer species that nest in the United States and Canada. They are beautiful and hateful, real ‘junk yard dogs’. They are by far the most common of all the winter hummers that we encounter. The bulk of the Rufous population spends the winter in Mexico. Their known nesting range includes Northern California, Washington, Oregon, Central Idaho, Western Montana, Southwestern Alberta, British Columbia and as far north as Southeastern Alaska in the area around Seward. I would not be surprised to learn that Rufous nesting had been documented in other areas of the United States. The very fact that we have documented Rufous in the Southeast in every month except June gives us pause to speculate about the accuracy of what we now know as their nesting grounds. In the state of Georgia in May, we have had adult males and adult females on site within three miles of each other.
On birding trips to the port city of Seward, Alaska, we have observed adult males on breeding territory and females flying with nesting materials in June. The commitment to complete their nesting must be accomplished ‘before the snow flies’. As soon as the young havefledged, there appears to be a mass exodus back to the warmer climate of Mexico. Sounds like I’m quoting here from your friendly field guide. Enter the role of amateurs in ornithology. First, our good friend and mentor, Nancy Newfield of Louisiana, started the furor with her pioneering work that located hundreds of Rufous wintering in her home state. Our own HBSG studies have now painted an even broader picture of where these birds live in winter. This winter alone we have captured and banded over 100 Rufous in our study area. A new assumption is now suggested. It would appear to us that a part of the Rufous hummingbird population is composed of birds that are no longer ‘tropical’ birds. This is supported by 22 individual return birds being recaptured at or near there original winter banding location this season (winter 1997/98). Many of these individuals have returned 3, 4 and even 5 years in a row.
This phenomena of a separate population of Rufous might even suggest that now or in the future these individuals might be considered a separate race. There is precedent in other species of hummingbirds for separate races. Part of our study is to accurately record and photograph those Rufous that we encounter in an effort to determine if there are plumage or structural differences that would support such a hypothesis. What cannot be denied is that the Rufous that we do encounter year after year are not vagrant birds. These hummers that we are now calling non-tropical birds have been generally referred to by the ornithological community and writers as vagrants, wanderers, lost, off course, sick or genetically impaired. It is our belief that although their ancestors may well have been genetically altered some untold number of generations ago, that defect in the gene that controls migration is now normal for this U.S. population. The fact that we have some very localized areas all over the Southeast, not just on the Gulf coast, where new Rufous occur year after year would appear to take the element of chance out of the equation in their selection of wintering sites. It is, in our opinion, a decision over which these non-tropical Rufous have no control. They are directed to these wintering sites by the genes of ancestors that have wintered there successfully. It is not known in our proposed scenario about the timing and merging of these separate populations of Rufous at a breeding site. However, if these Rufous are confined to a particular breeding area where they will encounter others with a similar genetic disposition, the prospects for a wintering population of Rufous may be on the verge of an explosive expansion. It may have already occurred and we are just beginning to document the fact. Wouldn’t it be neat to know that if you hung out your feeder in winter, Rufous would be as dependable as White-throated sparrows, Juncos and other winter residents? Tiny numbered bands on tiny hummer legs have given us a very special window into the life of these Rufous. We have long advocated that Rufous could not simply be dismissed as vagrants. But, it was not until we had accumulated mountains of evidence to the contrary did most ornithologists take any notice. This is as it should be in the scientific community.
A few details about Rufous. Females are larger than males, this is true in many hummingbird species. Females, adults in particular, have many irridescent feathers in the throat, unlike our more common female Ruby-throated who are ‘plain-throated’. Males as young birds have white tips on their outer tail feathers (rectrices), as do adult females. Only when they molt into their adult male plumage will they get the all dark tail feathers. After fledging, young males soon start to molt their all-green feathers of the back. These new feathers will be rufous colored (or commonly called brown). A ‘brown-backed’ hummingbird at your feeder in winter will be a male Rufous. Some very young male Rufous may show little or no brownish feathers in the back.
Normally, male Rufous will show considerable rufous color in the area of the rump and in the tail feathers themselves. The outside tail feathers in males will be 2/3 to 3/4 rufous colored at the basal end where they go into the body. Females of all ages will normally be rufous only 1/3 to 1/2 the length of these same tail feathers (Stiles 1972). The shorter wings of males beat faster than females and have a higher pitch that is noticeable in flight. Males tend to be a bit brighter in those areas of rufous coloring than females. The area of iridescence on the individual gorget feathers is much wider in males than in females and the color that you perceive will be much more shimmering. In our experience, if a Rufous has shiny gorget feathers on the sides of the throat, it is a male.
The first molt of any feathers that we normally see is on the underparts. In very young wintering Rufous, the loosely textured feathers of the breast and belly are easily dislodged. The feathers of the wing molt symmetrically from the body sides outward. Normally, when we see a Rufous with all new wing feathers except the outside two on each side, they are subject to leave almost any time. Even though the brilliant gorget feathers will continue to erupt from their sheathing during the winter months, the back of a male Rufous will be essentially all-brown before the gorget color is complete.
Males tend to have a much harsher tone to all their vocalizations. In addition, males are much more active vocally than females. Even as very young birds, males in winter begin to hone the intimidation skills that they will employ on their breeding grounds to dominate a breeding territory. Like other hummingbird species, young wintering Rufous males appear to do their version of a territorial morning song, in effect a declaration of territory. With experience, you can tell whether a bird is a male or female simply by their voice and how and when they use it.
Rufous hummingbirds are very cold hardy. They are hatched in a cold climate, they spend nights on nesting grounds where the temperatures are near freezing. They migrate down mountain corridors where the temperatures are cold. Finally, these U.S. Rufous are continually being refined by the genes of cold hardy ancestors that have endured severe winters. We regularly have Rufous in the Southeast that seem little effected by nighttime temperatures of 0 to 20 degrees F. The presence of Rufous going about their daily routine in times of severe cold requires rethinking our impression of hummingbirds in general.
Unfortunately, in many cases much of the information about Rufous available to the public is both incomplete and inaccurate. The very nature of birding field guides will always have them playing ‘catch-up’ to the facts. Revisions and new editions are never far behind. In my opinion, the single best paper on Rufous hummingbird is the new species account by our friend, Dr. William Calder of the University of Arizona. This booklet is part of the new Birds of North America series being published by the American Ornithologist’s Union and The Academy of Natural Sciences, Philadelphia. We hope to have some exciting news about making these booklets available to our members later as they are published.