Date & Time: October 23, 2007. First observed by homeowner on 17 October 2007 and still present as of this writing (October 26, 2007). I arrived around 10:00 a.m. and waited about 15 minutes before the bird made an appearance. I then set up my trap at 10:25 a.m. and caught the bird at 10:27 a.m. The bird was banded and released at 10:47 a.m. under Federal permit No. 23156, and Michigan permit No. SC 1303. The bird had not returned to the feeders within an hour after being released.

Location: At the home of Dave and Sandy Schafer in Dewitt, Clinton Co., Michigan.

Observer (s): Allen Chartier, Adam Byrne

Equipment: Photographed in-hand with digital camera (attached to this document). All measurements were made using digital calipers. Bill corrugations were determined by viewing through a 10x loupe, as they are impossible to accurately determine any other way.

Viewing conditions: The sky was overcast and the light dim and diffuse. The bird was banded, measured, and weighed, indoors and photographed outdoors.

Description: When the bird first made an appearance at the feeder, it was apparent that it was a Rufous or Allen’s Hummingbird, based on peach-rufous on the flanks, and an irregular blotch of iridescent throat feathers. This observation was made with my naked eye from a distance of about 10-feet. The bird was then captured for banding, and it was aged, sexed, and identified in that order. The proper use of Stiles (1972) for banders requires that an individual Rufous/Allen’s Hummingbird in-hand be correctly aged and sexed before a species determination can be made (B. Sargent and N. Newfield, pers. comm.).

Age: The bird was aged as after hatch-year (adult) based on the absence of shallow groovings or corrugations on the upper mandible. This is universally recognized as the most reliable method for age determination in hummingbirds (Ortiz-Crespo, 1972).

Sex: The upper tail coverts and rump were entirely green. The rufous on the base of the central rectrix (r1) was restricted to about the basal 25%, and was completely covered by the green upper tail coverts. As the bill corrugations indicated the bird was adult, plumage alone is enough to confirm the bird was a female, but these additional characters support that this bird was a female.

The wing measurement of 43.54 mm was 0.1 mm longer than any age of male Rufous or Allen’s given in Stiles (1972), so this measurement is also an indication that the bird was female.

The bill measurement (exposed culmen) can sometimes be helpful for determining sex as indicated in Table 1 in Stiles (1972). This bird’s exposed culmen measurement of 18.87 mm was longer than males of any age of Rufous, and longer than males of nominate Allen’s (S. s. sasin), and was at the upper range for female Rufous and shorter than any age or sex of the longest sedentarius subspecies of Allen’s*.

The pattern of iridescent gorget feathers on the throat can sometimes be helpful in determining the sex of Selasphorus hummingbirds. This bird had 24 clustered together in the center of the throat (see photos). This pattern could occur in either immature males or females, and the number of iridescent feathers varies considerably and is not particularly useful for supporting an age determination. There is a tendency for immature males and immature females to have fewer iridescent feathers, so this bird’s throat pattern weakly supports it as an adult female (I’ve had immature females with up to 22 iridescent throat feathers, and adult females with as few as 9).

Species: Given that the bird was an after hatch-year (adult) female, using Stiles we can determine whether this bird was a Rufous or Allen’s Hummingbird using several additional measurements and observations. The presence of notching and/or emargination on the second rectrix from the center (r2) is one feature that can often be observed in the field to confirm Rufous, and is considered diagnostic. This individual had noticeable notching and emargination on both webs of the second rectrix (see photos), which confirms that this bird was a Rufous Hummingbird. Using Figure 3 in Stiles (1972), the shape most closely matched figure Bb.

As additional support for the identification, the widths of two other tail feathers, the central rectrix (r1) and the outermost rectrix (r5) were measured. The width of the central rectrix (r1) was measured as 8.52 mm. This is wider than adult females of either subspecies of Allen’s Hummingbird given in Stiles (1972) and provides additional confirmation of the bird as a Rufous.

The width of the outer rectrix (r5) was measured as 3.62 mm. This is broader than the maximum range for immature female Allen’s (max. 3.3 mm for both subspecies given in Stiles 1972) and so provides additional conclusive and diagnostic support to the identification as Rufous.

Tail measurements are often not very useful. This bird’s tail measurement of 28.5 mm is above the maximum for adult females of both subspecies of Allen’s (Stiles 1972) and is at the upper end of the range for adult female Rufous. So tail length is somewhat useful in this case. Also, the wing measurement of 43.54 mm is above the maximum for adult females of nominate Allen’s but is shorter than the maximum of the sedentarius subspecies of Allen’s, so weakly supports the identification as Rufous.

Molt: There was very little body molt evident on this bird, mainly on the lower back. The outer 3 primaries (p8-p10) were old and worn, and the inner primaries (p1-p7) were recently replaced and contrastingly shiny black. All the rectrices appeared fresh and probably recently replaced.

Fat/Weight: The bird had a fat code of 1 (0-3 scale) and weighed 3.32 grams, about average for an adult female planning to overwinter.

Voice: Brief, sharp chip note when the bird was released. More strident than Ruby-throated gives.

Similar Species: Allen’s Hummingbird is the species most similar to Rufous Hummingbird. On this bird, the diagnostic "notched and emarginated" second rectrix (r2), measured widths of the inner (r1) and outer (r5) rectrices were the primary characters confirming the identification, with tail length and to a lesser extent wing length supporting the identification.

Experience: I have seen dozens of Rufous Hummingbirds in several states, banded 38 in Michigan, Ohio, Indiana, and Ontario, and handled ~35 in Louisiana in February 2003 with Nancy Newfield, and handled about a dozen in Arizona in 2006 helping other banders. I have seen several Allen’s Hummingbirds on two trips to California and once recently in Arizona, and handled 3 in Louisiana in February 2003. As a trained, licensed hummingbird bander, I am familiar with all pertinent in-hand criteria for distinguishing Rufous from Allen’s Hummingbird, in addition to known field criteria for separating these species.

When report was written: This report was written on October 26, 2007 based on data and photos taken during the banding process.

References consulted: None were consulted while observing the bird in the field, nor were any used to write notes in the field or to write this report. Stiles (1972) and Pyle (1997) were available during the banding of the bird.

Ortiz-Crespo, F.I. 1972. A new method to separate immature and adult hummingbirds. Auk 89: 851-857.

Pyle, P. 1997. Identification Guide to North American Birds:
Part 1. Slate Creek Press, CA.