Location Code: OH-31
Ohio Rare Bird Report
Species: Rufous Hummingbird (Selasphorus rufus), adult female
Date & Time:November 14, 2008. First observed by homeowner on October17, 2008 and was last observed by the homeowner on December 12, 2008. I arrived around 9:00 a.m. and watched for the bird to make an appearance, which had been seen at 8:00 this morning. The bird had been very infrequent on occasion and by 9:30 the bird had not appeared, so I set up my trap. The bird finally made an appearance, and went into the trap, at 11:54 a.m. The bird was banded and released at 12:09 p.m. under Federal permit No. 23156, and Ohio permit No. 0208. The homeowner reported that the bird returned to the feeder in mid-afternoon.
Location: At the home of JoAnn LaMuth in Bexley, Franklin Co.
Observer (s): Allen Chartier. Homeowner (JoAnn LaMuth), Jim McCormac, and several others also present.
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 partly cloudy and the light conditions were excellent. The bird was banded, measured, weighed, and photographed outdoors.
Description: When the bird first made an appearance at the feeder and trap, it was not examined very closely in order that it could be captured quickly. Once the bird was in-hand it was aged, sexed, and identified in that order. The proper use of Stiles (1972) for banders requires that an individual Rufous/Allenís 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 less than 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 42.78 mm was at the short end of the range for adult female Rufous given in Stiles (1972) and also within the range for adult female Allenís of both subspecies, and near the large end for immature male Rufous and within the range of sedentarius Allenís. So, the wing length was only somewhat useful for determining the sex of this bird.
The bill measurement (exposed culmen) can sometimes be helpful for determining sex as indicated in Table 1 in Stiles (1972). This birdís exposed culmen measurement of 16.54 mm was at the short end any age or sex of Rufous and nominate Allenís (S. s. sasin), but shorter than the smallest adult of the sedentarius subspecies of Allenís*. So, in this case, the bill measurement was not particularly useful for determining the sex of this bird.
The pattern of iridescent gorget feathers on the throat can sometimes be helpful in determining the sex of Selasphorus hummingbirds. This bird had only a single iridescent gorget feather in the lower part of the throat, just above a bare area where feathers were missing on the lower throat (see photos). Any number of the missing feathers could grow in iridescent, so there is no value in assessing the gorget of this individual.
Species: Given that the bird was an after hatch-year (adult) female, using Stiles we can determine whether this bird was a Rufous or Allenís 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 Aa.
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 7.84 mm. This is very slightly wider than adult females of the nominate subspecies of Allenís Hummingbird given in Stiles (1972) and is close to the upper range for the sedentarius subspecies of Allenís, and so is suggestive of Rufous but not diagnostic. The width of the outer rectrix (r5) was measured as 3.63 mm. This is broader than the maximum range for adult female Allenís (max. 2.7 for sasin and 3.0 mm for sedentarius as 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 birdís tail measurement of 28.5 mm is above the maximum for adult females of both subspecies of Allenís (Stiles 1972) and is even slightly above the upper end of the range for adult female Rufous. So tail length is somewhat useful in this case.
Molt: There was some body molt evident on the throat and breast of this bird. The outer 8 primaries (p3-p10) were old and worn, and the inner primaries (p1-p2) were recently replaced and contrastingly shiny black (p2 was about 90% grown in). The third and fourth rectrices were old, while r1, r2, and r5 appeared fresh and had probably recently replaced.
Fat/Weight: The bird had a fat code of 1 (0-3 scale) and weighed 3.72 grams, a little above average for an adult female planning to overwinter (typically 3.4-3.6 in my experience).
Voice: Brief, sharp chip note when the bird was released. More strident than Ruby-throated gives.
Similar Species: Allenís Hummingbird is the species most similar to Rufous Hummingbird. On this bird, the diagnostic "notched and emarginated" second rectrix (r2) and the measured width of the outer (r5) rectrix were the primary characters confirming the identification, with tail length supporting the identification somewhat.
* There are two subspecies of Allen's Hummingbird. One is the widespread and migratory nominate subspecies (Selasphorus sasin sasin) breeding from coastal northern California to coastal southern California and mainly migrating southward into Baja California, Mexico. The other is a more range-restricted and generally non-migratory subspecies (S. s. sedentarius), breeding on California's Channel Islands and the adjacent mainland (around Los Angeles). But sedentarius presents some problems, because it is intermediate between S. s. sasin and Rufous in some characters. And, while sasin has a shorter bill than Rufous, sedentarius has a longer bill! If sedentarius were entirely sedentary, this would not be an issue. But, I've been told (N. Newfield, pers. comm.) that the first specimen of Allen's Hummingbird collected in Louisiana actually fits sedentarius! So, however remote the possibility, sedentarius must also be considered.
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.
Stiles, F.G. 1972. Age and Sex Determination in Rufous and Allen Hummingbirds.The Condor 74: 25-32.