Location Code: GEN5
Michigan Rare Bird Report
Species: Rufous Hummingbird (Selasphorus rufus), adult female
Date & Time: December 6, 2009. First observed by homeowner in late September and last observed on December 29, 2009. It was coming to the feeder with a second bird, probably an immature male Ruby-throat based on her description, until early November. I arrived around 10:00 a.m. and set up my trap at 10:15 a.m. and caught the bird at 10:23 a.m. The bird was banded and released at 10:41 a.m. under Federal permit No. 23156, and Michigan permit No. SC 1303. The bird had returned to the feeder by about 11:30 a.m. according to the homeowner.
Location: At the home of Karen Bennett in Flushing, Genesee Co.
Observer (s): Allen Chartier, Nancy Chartier, Karen Bennett (homeowner), Jeff Buecking, Maureen Buecking.
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 excellent. The bird was banded, measured, weighed, and photographed indoors.
Description: When the bird first made an appearance in the area, it was apparent that it was a Rufous or Allenís Hummingbird, based on peach-rufous on the flanks, and a large triangular patch of iridescent throat feathers, which appeared black. This observation was made with my 10x Swarovski binoculars 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/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 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 plumage characters support that this bird was a female.
The wing measurement of 42.25 mm was near the low end of the range for adult and immature female Rufous given in Stiles (1972). It is also near the large end of the range for immature male Rufous and Allenís, so the wing chord measurement supports the sex of this bird as female.
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 17.97 mm was near the middle of the range given for adult and immature females Rufous. It is also above the large end of the range for immature male Rufous but in the middle of the range for male Allenís, so the exposed culmen measurement somewhat supports the sex of this bird as female.
The pattern of iridescent gorget feathers on the throat can sometimes be helpful in determining the sex of Selasphorus hummingbirds. This bird had 33 clustered together in a triangular patch at the bottom center of the throat (see photos). This pattern is more indicative of females than males, though the number of iridescent feathers varies considerably. It is not particularly useful for supporting an age determination.
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). Using Figure 3 in Stiles (1972), the shape most closely matched figure Bb. This character is diagnostic for Rufous Hummingbird. Additional characters used for identification were the widths of two other tail feathers. The central rectrix (r1) and the outermost rectrix (r5) were measured. The width of r1 was measured as 8.18 mm. This is near the mid- range for adult female Rufous and outside the range for both subspecies of Allenís Hummingbird* given in Stiles (1972) so also confirms Rufous. The width of r5 was measured as 3.65 mm. This is broader than the maximum range for immature female Allenís (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 birdís tail measurement of 28.0 mm is above the maximum for adult females of both subspecies of Allenís (Stiles 1972) and is at the upper end of the range for adult female Rufous. So tail length is somewhat useful in this case.
Molt: There was no body molt evident on this bird. The outer 2 primaries (p9-p10) were old and worn, and the inner primaries (p1-p8) were recently replaced and contrastingly shiny black, appearing to be in suspended wing molt as is the case with most Rufous Hummingbirds banded in our region. All rectrices were new.
Fat/Weight: The bird had a fat code of 2 (0-3 scale) and weighed 4.01 grams, above average for an adult female planning an extended stay.
Voice: None heard.
Similar Species: Allenís Hummingbird is the species most similar to Rufous Hummingbird. On this bird, the diagnostic "notched" second rectrix (r2), the measured width of the outer (r5) rectrix, and the measured width of the central (r1) rectrix all confirmed the identification as Rufous Hummingbird and eliminated Allenís, with some support also from the wing length and tail length.
Experience: I have seen dozens of Rufous Hummingbirds in several states, banded nearly 60 in Michigan, Ohio, Indiana, and Ontario since 2001, 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 Allenís 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 Allenís Hummingbird, in addition to known field criteria for separating these species.
When report was written: This report was written on December 12, 2009 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.
Stiles, F.G. 1972. Age and Sex Determination in Rufous and Allen Hummingbirds. The Condor 74: 25-32.