Simply stated, sorting out many of the female and immature hummingbirds in the American West is a challenge. In addition to being very plastic in terms of shape and profile, feather iridescence and plumage variation associated with age combine to confound even the most experienced observers, particularly when it comes to the genus Selasphorus. This genus includes three North American species: Allen's Hummingbird, Broad-tailed Hummingbird, and Rufous Hummingbird. Separating them in their female and immature plumages has spawned many a lively debate.
On 11 June 2012 Shawneen Finnegan and I were birding along Cow Creek Rd. e. of Azalea, Douglas County, Oregon. We came across a yard full of blooming Red Hot Pokers (Kniphofia uvaria) that was teeming with Rufous Hummingbirds. It was hard to to count, but there were about 20-25 hummers buzzing about feeding on these flower heads. Almost all were immature or female-type Rufous Hummingbirds, so I found a roadside vantage point that allowed me to photograph several different individuals. Ultimately, I got photos of about ten different birds, all of which seemed to sub-adults. This photo essay shows some of the variation that one might see in immature Rufous Hummingbirds. I captured all of these images at the described site on 11 June 2012.
The first five photos show variation in back color, most notably how much rufous or rust color there is on the back, rump, and upper tail.
Fig. 1. This bird was presumed to be a first-summer male based on the extensive rufous on the upper tail coverts and rump, as well as the near solid dark feathering on the throat.
Fig. 2. This presumed female shows an entirely green back, rump and, upper tail. Generally, perched Rufous Hummingbirds show some exposed rufous coloration on the rump and upper tail. I wondered if this might be a first-summer female, as it is conceivable that the rusty edges on the dorsal feathers of a first-summer female may have worn off this far into a plumage cycle. Hatch-year female Rufous Hummingbirds typically show less dense dark feathering on the lower throat. Note the somewhat alert and stretched-out posture of this bird, which tends to make it look bigger and longer-tailed. The length of the tail feathers contribute to a longer looking tail and support the notion that this is an after hatch-year female. Some might look at this bird and call it a female Broad-tailed Hummingbird, but Howell (2002) suggests that female Broad-taileds have a "colder" face pattern lacking the warmer subtle rufous tones shown by this bird.
Fig. 3. This bird shows what I would call intermediate rufous coloration on the rump and lower back, which makes it a challenge to sex. Notice the compact posture (neck not extended) of this bird and how it looks smaller and shorter-tailed in comparison to the bird in Fig.2. The tail feathers on this bird do look relatively short and may not be fully grown.
Fig. 4. This individual shows a mostly green rump and back with limited rust coloration showing. This back pattern seems to be pretty typical among immatures, particularly females. The tail look fairly short on this bird.
Fig. 5. Given the amount of rufous on the lower back, rump, and upper tail, which is beyond the maximum typically seen on hatch-year birds, I presumed this bird to be an after hatch-year (first summer) male.
The next seven photos show variations in the throat pattern and flank coloration of immature Rufous Hummingbirds. Of particular interest to me is the amount of dark feathering each bird shows on the chin and center of the throat. Birds that were presumed to be immature males seemed to show more extensive and richer rufous wash on the flanks, along with more dense dark feathering on the throat.
Fig. 6. I find the ventral pattern of this bird to be somewhat ambiguous. Flanks are washed out looking, but the amount of dark feathering below seems pretty dense.
Fig. 7. This bird approaches the minimum amount of dark feathering on the throat and the flank coloration is limited and a bit washed out to my eye. I would call this a hatch-year female. Also, note the elongated and rather streamlined profile of this bird.
Fig. 8 & 9. Two images of the same presumed after hatch-year male from different angles (above and below). Note the amount of rust coloration on the part of the back that is visible (above) and also note the rather solid dark feathering on the throat. This bird had more dark feathering on the throat than any other immature/sub-adult that we saw at this site. Finally, compare the scrunched-up puffed-out shape of this bird with that of the bird in Fig. 7.
Fig. 10. The amount of dark on the throat of this bird falls between the two birds in the three images immediately above (compare to birds in Figs.7-9). Note the fairly uniform pattern created by the dark lines of feathers across the entire throat. The rust on the flanks seems a bit darker than the first of the ventral shots (Fig. 6). I suspect that this bird is an immature male.
Fig. 11. When hovering to feed, all hummingbirds have a tendency to look larger and more elongated than they do when perched.
Fig. 12. This individual shows heavy dark feathering on the sides of the throat and lower cheek on the throat, which pales towards the center of the throat and chin.
I recognize that most folks reading this article aren't likely to invest much time and energy into aging and sexing every Rufous Hummingbird that they see (it can be an exercise in futility). Since I live in Oregon, where Rufous is the default Selasphorus across most of the state, appreciating the variability in Rufous Hummingbirds can come in handy. Occasionally, we see out-of-range reports of Allen's (nesting range extends to Oregon's southern coast) and Broad-tailed Hummingbirds (not known to nest in Oregon, but occurs as a rare migrant). Often times, such reports involve female/immature type birds. Here, the first order of business when considering a report of an out-of-range Selasphorus is to determine why it's not a Rufous.
In conclusion, it's important to point out that I've not studied museum skins of Rufous Hummingbirds, nor have I done any hummingbird banding, thus much of the commentary herein is speculative. I would welcome any comments on the specific age and sex of the birds in this collection of images. The main point was to display some of the individual variation one might encounter when observing this species in the field.
Howell, Steve N. G 2002. Hummingbirds of North America: The Photographic Guide. Academic Press: A Harcourt Science and Technology Company, London, UK.
Williamson, Sheri L. 2001. A Field Guide to the Hummingbirds of North America (Peterson Field Guide Series). Houghton Mifflin Co. New York, NY.
The links below provide additional photos of Rufous Hummingbirds and discussion of Selasphorus hummingbird ID.