No. 189 BATON ROUGE, LAFebruary 2000

LOS NEWS, Page 2

Table of Contents

Searching for IBWO
IBWO Tee-Shirts
Year of Discovery
Yard List ‘99 Final Call
The Botanical Birder
Camellias
Ag Wetlands
Selasphorus ID Article
Selasphorus Figure 1
Selasphorus Figure 2
Selasphorus Figure 3
Selasphorus Figure 4
LOS Pelagics 2000
Winter Meeting Report
Swallow-tailed Kites
Waxwings Poem
Rare Bird Alert
BirdSource
New Members
LOS Officers
LOS Sales
Membership Form
 
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Table of Contents

Let’s take another look - "rufous" hummingbirds

by Donna L. Dittmann & Steven W. Cardiff

In a previous article, we discussed Ruby-throated Hummingbird and its "look-a-likes." To complete the review of identification of "small hummingbirds" occurring in Louisiana, we need to cover the genus Selasphorus, as well as a long-shot look-a-like, Lucifer Hummingbird.

Status

Rufous Hummingbird (Selasphorus rufus) breeds from southern Alaska through western Canada and south (primarily in the mountains) to southern Oregon and central Idaho. It winters primarily in western Mexico. Many birds apparently use an oval migration route, moving SE in fall and NW in spring. Small numbers are found with increasing regularity east of the normal route during fall migration, and increasingly larger numbers are found in late fall and winter throughout the southeast, but mainly close to the Gulf Coast from southeastern Texas to western Florida. In Louisiana, "fall" arrivals can occur as early as late July, with numbers gradually building into October. Most of these early individuals are adults that are known or presumed "returnees" that successfully over-wintered the preceding year(s). Some returning adults, however, do not appear at wintering sites until relatively late in the fall or early winter. Some of the individuals present for brief periods during late summer-early fall, especially immatures, are thought to represent transients, although further study is needed to confirm the true status and final destinations of these birds. The majority of "wintering" individuals arrive from late October into November and December, and remain into February, March, or even April. This species is our most common wintering hummingbird, with numbers fluctuating from several dozen to several hundred per winter. Most individuals spend several months at a specific site before departing for the breeding grounds, but new arrivals and departures continue to occur through the winter, causing much confusion and speculation regarding late fall and winter movements and population dynamics of this (and other) species on the Gulf Coast. Some spring records may pertain to northbound migrants from outside our region, although this is difficult to prove in the presence of so many wintering individuals.
 
Allen's Hummingbird (S. sasin) breeds from southwestern Oregon south to coastal southern California; the southernmost population is resident. The species winters primarily in Baja California and mainland west Mexico. It is a vagrant to Louisiana and is on the LBRC Review List. The first record for the state was in Reserve, 8 October 1975-6 March 1976 (specimen). Since then, records have averaged about one to a few per season. Because of the difficulty of identification between Rufous and Allen's hummingbirds, most of the earlier records were of adult males; "suspected" immature male Allen's, sometimes present at feeders for months, were usually not conclusively identified until they finished molt into adult plumage. Unfortunately many wintering individuals depart just before, or immediately upon completion of molt, providing little time to acquire proper documentation. More recently, a number of Allen's have been discovered among unidentified Selasphorus during routine winter hummingbird banding operations. "Suspected Allen's" can usually be targeted for capture and in-hand ID confirmation by our resident hummingbird banding specialists. Seasonal occurrence is similar to Rufous Hummingbird, with most arriving during late October and November, and remaining into February and March, sometimes into April; banded returnees have been detected as early as August. The remote possibility exists that some "accepted" records may actually pertain to green-backed Rufous Hummingbirds or hybrids (see below).
 
Broad-tailed Hummingbird (S. platycercus) breeds in the mountains of the western US from north-central Idaho, southwest Montana, northern Wyoming south to southeastern California, west Texas, and the highlands of northern and central Mexico. This species winters throughout the highlands of mainland Mexico. There is also a disjunct resident population in Chiapas and Guatemala. It is a vagrant to Louisiana and is on the LBRC Review List. The first record was in Baton Rouge in 1952, a bird present at a feeder (Lowery 1974, Louisiana Birds). Twenty-five years elapsed until the next record, and thereafter the species was recorded only every few years. From the mid-1990s to the present, the species has become an annual visitor, often with multiple records per season. Birds are typically first detected at feeders in late October and November, and can remain into April. There are only a few records of "returnees," which tend to arrive relatively earlier in the fall.
 
Lucifer Hummingbird (Calothorax lucifer) occurs primarily in the highlands of north and central Mexico. It breeds locally north to extreme southeast Arizona, extreme southwest New Mexico, and extreme southwest Texas. There are currently no Louisiana records, but, individuals have wandered in the fall as far northeast as Hays, Bee, and Aransas counties in central Texas, and therefore, the species is a candidate to eventually wander a little farther east.

Identification basics

As mentioned in the previous article, best sources for hummer ID are NGS 3rd Edition, which provides a fair treatment of basic ID; Advanced Birding (Kaufman 1990) includes a very helpful discussion of this group; and Identification Guide to North American Birds, Part 1 (Pyle et al. 1997), though somewhat difficult to absorb, provides lots of information. "The Age and Sex Determination in Rufous and Allen's Hummingbirds" (F. Gary Stiles 1972, Condor 74: 25-32) is an invaluable resource. Regional tapes or CDs include helpful recordings of hummingbird calls and songs (some species).
 
Basic ID hints
For basic hummingbird ID hints, review the previous article on "Ruby-throated and its look-alikes" (LOS News No. 188). We cannot stress enough how important it is to become familiar with the commonest species, and to take advantage of opportunities to study the less common species as frequently as possible.
 
Molt
Please refer to LOS News No. 188, pgs 14-15; "rufous" hummingbirds follow the same pattern. This group of hummingbirds also shows strong sexual plumage dimorphism. Adult males have iridescent gorgets. Immatures generally resemble adult females. Through the fall and winter, immature males add iridescent gorget and adult type body feathers. The gorget is completed just prior to spring migration and is the last part of the plumage to be replaced. This has important ID ramifications for Rufous/Allen's hummingbirds. As mentioned in the previous article, if you have, or suspect multiple individuals of the same species, molt (presence or absence) may help you recognize specific birds. The exact pattern of gorget, tail (new versus old feathers, or missing feathers, etc.), and back feathers, are not only helpful ID characters, but may also help to recognize specific individuals.

Overview of "rufous" hummingbirds

There are five species and three genera of small hummingbirds occurring in North America that have extensive rufous in the plumage or have rufous-based outer tail feathers. Selasphorus (3 species) and Calothorax (1 species) are discussed below. The fifth, Bahama Woodstar (Calliphlox evelynae) is a casual vagrant to southern Florida. An adult male Bahama Woodstar should cause little confusion with other species (see NGS guide); females and immatures are easily separated from Selasphorus and Calothorax on the basis of rufous-tipped, instead of white-tipped, outer tail feathers.
 
Adult males of Selasphorus and Calothorax are easily identified, except of course, the superficially similar Rufous and Allen's hummingbirds. Females and immatures are much more similar (Fig. 1). All share rufous-based outer tail feathers and have rufous or bright buffy sides, and predominantly buff-colored undertail coverts. Compare also with smaller Calliope Hummingbird, which has rufous at the extreme base of the outer tail feathers buffy sides, or buffy or white undertail coverts; this species was covered in the previous article. Although Archilochus can be quite buffy in the fall (especially fresh immatures), the buff coloration is restricted to the sides, the undertail coverts are usually white or grayish-white (only occasionally buff), and there is never any rufous in the rectrices; both species of Archilochus typically look more masked. Calothorax has a slightly decurved bill throughout its length, unlike any of our Selasphorus or the hummingbirds covered in the previous article. As in the case of the other small hummingbirds so far covered, females average slightly larger than males.
 
Rufous Hummingbird
Plumage. Adult males are unlikely to be confused with other species. The combination of extensively (usually) rufous nape, back, and upper tail covers, separate it from all other species. The crown may be dull rufous or green. The gorget is orange-red and slightly flared at the sides (Fig. 2). Fresh gorget feathers are edged with green and the gorget can glow green to yellow to orange-red, depending on the angle of light. Below the gorget is a broad white bib. This bib extends up onto the sides of the throat and contrasts with the rusty sides. In some birds, the breast and sides are entirely rusty, paling slightly only in the center of the breast; other individuals have a clean white division between the rusty sides. The belly is white and the undertail coverts are buff. The tail is entirely rufous with dark tips or outer webs (Fig. 3). The tail feathers are all strongly pointed and the shape is graduated (central feathers are longest). The inner web of rectrix #2 is notched and rectrix #5 (average width 2.64 mm; McKenzie and Robbins 1999 Western Birds 30:86-93) is "relatively broad" (Fig. 3). These two characters are important, along with wing and tail length, to distinguish adult male Rufous from adult male Allen's Hummingbird. Adult females have iridescent golden-green upper parts, including the crown, nape, back, and uppertail coverts. The sides are bright buffy and the buff coloration may cross the breast. The center of the breast and belly are white, but the undertail coverts are predominantly buff. The outer tail feathers are rufous-based, with black subterminal bands and white tips (Fig. 3). The two central tail feathers are predominately green, sometimes black-tipped, and can occasionally show extensive rufous sides. The tail is somewhat rounded, rather than forked. The combination of these characters separate female Rufous from Archilochus (Ruby-throated and Black-chinned) and Calypte (Anna's and Costa's). The white throat is stippled with small gray spots or tiny iridescent green dots, and there is usually a prominent colored central gorget spot or wedge. Like the male, iridescent gorget feathers are orange-red (but may appear green or even black in poor light). Although not distinctly masked like Archilochus, Rufous have relatively dark faces that generally blend from the crown (without the distinctly darker-cheeked appearance), to below the eye (compare with Calliope and Broad-tailed hummingbirds; Fig. 1). The tail is relatively long and usually extends well past the wing tips (separating Rufous from Calliope Hummingbird) when the bird is perched. The width (range 2.7-4.0 mm; Pyle 1997) of rectrix #5 and notched rectrix #2 are critical characters to separate adult female Rufous from adult female Allen's Hummingbird, which are otherwise virtually identical. The plumage of immature birds is similar to that of adult females, although immature females may completely lack orange-red gorget feathers. Immature males usually gain at least a few adult gorget feathers by early fall; otherwise the throat appears somewhat more stippled than that of a female. During the late winter and early spring, immature males molt in the remainder of their gorget. The incoming iridescent feathers may assume an endless variety of patterns. The "full gorget" is normally the last part of adult plumage acquired. Immature males generally have more rufous in the central tail feathers, as well as more rufous (rather than buff) sides than immature or adult females. Like adult males, the rufous sides contrast with the prominent "white bib" that borders the gorget area (Fig. 4). The timing and pattern of feather replacement (particularly body molt) varies among individuals, and for this reason, individual immature male Rufous Hummingbirds may look quite different at the same time of the year (female-like vs. nearly adult male-like). The addition of rufous feathers to the back, uppertail coverts, nape, cheeks, and sides gives each bird nearly "their own look"--at least for a little while. Some birds may not obtain entirely rufous backs (see below), instead exhibiting a mixture of rufous and green feathers. During the mid- to late winter, birds molt wing and tail feathers. Birds with primary or tail molt may appear shorter- or longer- winged, possibly causing confusion with other species when seen only in silhouette.
 
Voice. The typical call is a soft "stick," which is most easily recognized when given as a single note. When doubled or tripled, it assumes a more electronic quality. When uttered rapid-fire, it sounds like electricity bouncing off high tension wires. Individuals often give the "stick" call when displaced from their favorite thicket by human activity. Otherwise, be alert, "unprovoked" vocalizing may signal the presence of other hummingbirds. The aggression call is a three note "EEK-ka-da" (reminiscent of that of Ruby-throated), sometimes repeated, or a single buzz "beezip." Rufous Hummingbirds are very aggressive towards each other and other species, and vocalize frequently.
 
Flight Display. Rufous Hummingbirds have a distinctive flight display. Males have a courtship flight that they perform above a perched female. The male flies high in the sky, then dives, outlining a large oval. Some birds, probably immatures, display over other hummingbird species (or other birds!) in the late winter and spring. These birds may not do full displays (just practicing)—beware of possible confusion between abbreviated "practice displays" of Rufous, and the "J-shaped display" of Allen's Hummingbird. Rufous Hummingbirds also will fly straight up, often a considerable distance (perhaps looking for intruders), then down and back to their favorite perch; this behavior may also be confused with the "J."
 
Allen's Hummingbird
Plumage. Separation of Allen's from Rufous, except for adult males possessing full gorgets and solid green backs, is difficult. In general, and as indicated by field guides, adult male Allen's are distinguished from Rufous by solid green backs and upper tail coverts. Individual back feathers may possess some rufous (for instance on the sides and base of an unworn feather), but the individual feather is never completely rufous. If a bird has completely rufous feathers in the back, then it is NOT an Allen's. In addition to the solid green back, Allen's have proportionately shorter wings (mean wing chord 38.11 mm compared to 40.62 mm) and tail (mean 24.94 mm compared to 27.90 mm ) than Rufous (as noted in the Rufous account above; measurements from McKenzie and Robbins 1999). Females and immatures are essentially identical to Rufous, and are best separated in the hand by wing and tail measurements, shape of the second rectrix, and width of the fifth (outer) rectrix. It is important to note that measurements are useful only when sex and age are known. For more information see Stiles (1972) or Pyle (1997).
 
Even "all-green-backed" adult males, with full gorgets, should be carefully examined, preferably in the hand, to confirm absence of rufous back feathers, other ID characters, and measurements-see pitfall below-when dealing with birds outside their normal distribution. Extremely good photographs or video may confirm a notch-less rectrix #2 and extremely narrow outer rectrix (even though accurate measurements may be impossible to obtain) --regardless, these subtle characters are virtually impossible to confirm even under ideal field conditions!
 
Voice. The call note of Allen's is indistinguishable from Rufous Hummingbird. Allen's also have the various aggressive notes, such as the "EEK-ka-da" attack call and buzz.
 
Flight Display. The flight display of Allen's is a "J" shape, often repeated 2-3 times, compared to the closed oval of Rufous. Again, be prepared for immatures performing anomalous display patterns.
 
Identification pitfall—"Green-backed" Rufous Hummingbirds. Several sources (as early as Ridway 1900; Manual of Birds of North America) have alluded to the possibility of entirelygreen-backed Rufous Hummingbirds. When fresh, the back feathers of Rufous Hummingbirds have narrow green edgings, but the underlying color is rufous. This is not to be confused with entirely green feathers. However, some Rufous do not obtain completely rufous backs. Instead, the back is mixed with a combination of green and rufous feathers. Rarely, Rufous Hummingbirds have all green backs (fide W. E. Baltosser)! Why some birds do not obtain full rufous backs is not understood.
 
The most recent review of green-backed Rufous Hummingbirds is by McKenzie and Robbins (1999). These authors located two museum specimens with green feathers covering more than 95% of the back area—thus appearing wholly green- backed. Based on wing and tail length, width of rectrix #5, and presence of a notch in rectrix #2, they believed that these specimens did not represent hybrids. Though their sample included 124 adult male-plumaged Rufous Hummingbirds, the true frequency of "all green-backed" Rufous in nature is not known. The existence of apparently "green-backed" Rufous, though certainly very rare, compounds an already difficult identification problem.
 
Hybrids between Rufous and Allen's have also been reported (including a couple of specimens examined by McKenzie and Robbins); birds with intermediate characters (back color, wing length, and measurements and shape of tail feathers) are believed to be hybrids.
 
Broad-tailed Hummingbird
Plumage. The larger size, rose-red or magenta gorget, longer bill, entirely green upper parts, and rufous-edged black tail separate adult male Broad-tailed Hummingbird from the other small hummingbirds. None of the other species possess this combination of characters. Adult male Ruby-throated Hummingbird is superficially similar, but it is slightly smaller, possesses a ruby-red gorget, a black mask, and a forked tail lacking rufous. Immature males and all females are superficially similar to Rufous Hummingbird because the bases of the three pairs of outer tail feathers are rufous with a black subterminal band and a white tip. Although the overall tail feather pattern is similar to a Rufous, each tail feather is broader—the white tips are more prominent by virtue of their larger size. The sides are buffy (like a female Rufous), never rusty, and the back appears a drabber green without the golden sheen typical of female or immature Rufous. The throat is white, finely stippled with green or gray dots. Immature males usually possess at least a few adult-type gorget feathers by late fall. The gorget is completed through the late winter. Apparently, adult females occasionally have magenta gorget feathers (Pyle 1997; William A. and Lorene L. Calder 1992; Birds of North America, Life Histories for the 21st Century, AOU No. 16, Broad-tailed Hummingbird; LSUMNS specimen) but further study is needed regarding frequency and to ensure that such individuals have been sexed properly. Females and immature males with colored gorget patches or feathers could potentially be confused with female Anna's or immature male Ruby-throated hummingbirds. Both those species would have relatively shorter, narrower tail feathers without any rufous. These species also appear more "masked." The face of the immature/female Broad-tailed is relatively plain; a line extends from the bill to the eye and divides the darker head from the white throat (Fig. 1). This character, combined with the overall appearance of the body plumage, can be suggestive of a Calliope Hummingbird (but the body proportions are very different). Broad-taileds never have any rufous in the back, nape, or upper tail coverts. The shape of a Broad-tailed is quite different from a Rufous, and those observers familiar with Rufous Hummingbird should immediately recognize a female/immature Broad-tailed as something different.
 
Voice. Call notes are somewhat similar to Rufous and Allen's, but more reminiscent of Calliope, and easily distinguished from these other species with practice. The typical call is a more drawn out "stoop ," "toop," or "teep" given singly or repeated, and can be quite loud. It is quite different from the "stick"-note of the Rufous. The difference is most easily detected when comparing single notes—and as a comparison of vowel sounds, a short "i" (as in stick = Rufous) versus an "oo" (as in school = Broad-tailed) versus "ee" (steep = Calliope). The "EEK-ka-dah" aggression call is huskier. Males also produce a loud high-pitched trill when they fly, caused by narrow outer primary tips. Unfortunately, this trill is rarely heard in Louisiana because adult males, relatively rare here, usually have worn primaries or wing molt by late fall-winter, and temporarily lose the "trill."
 
Lucifer Hummingbird
Plumage. Adult males are unmistakable with a blue-purple-violet gorget that extends well beyond the sides of the throat. The only species that has a similar-colored gorget is Costa's, but that species also has a violet crown. Females and immatures are superficially similar to Selasphorus and share a golden-green back, rufous-based and white-tipped outer tail feathers, and buffy underparts. Lucifer is separated from Selasphorus by its buff throat and bib – on Selasphorus these areas are white. The buff throat is plain and unmarked, lacking the stippled effect typical of Selasphorus species. The throat, bib, and upper breast are buffiest portion of the underparts. The buff fades to a paler, whiter belly. Like Selasphorus, the undertail coverts are predominantly buff. The face pattern is fairly well pronounced – a buffy pale postocular spot/streak borders a dark cheek patch that borders the throat (Fig 1). The tail is more prominently forked than on Selasphorus species. Immature males gain adult gorget feathers through the winter. The bill of Lucifer Hummingbird is gently decurved throughout its length, unlike our other small hummingbirds, which should further assist the ID.
 
Voice. Reported as series of squeaky notes or dry chips similar to Costa's Hummingbird (P. E. Scott, 1994, Birds of North America, Life Histories for the 21st Century, Lucifer Hummingbird; AOU No. 134)—the authors are not familiar with the vocal repertoire of this species.
 
Call or email for help!
If you see, or suspect that you have seen, a rare hummingbird at any time of year, or if you have any hummingbirds lingering in your yard during the late fall or winter, then you can report your find and/or seek identification help from a number of sources: Nancy Newfield (504-835-7231; colibri@gs.verio.net; hummingbird bander); or Laurence C. Binford (225- 274-1889) and Miriam Davey (225-291-4867) in the Baton Rouge area; or Dave Patton (318/337-232-8410; wdpatton@mail.lig.bellsouth.net; hummingbird bander) in the Lafayette area.
 
Tom Sylvest is compiling records of winter hummingbirds during winter 1999-2000. Let him know what's visiting your feeders (tomande@stargazer.net).
 
Details of LBRC Review List species should be submitted to: Secretary, LBRC, 119 Foster Hall, Museum of Natural Science, LSU, Baton Rouge, 70803.
 
Specimens at LSU Museum of Natural Science provided an invaluable resource to confirm ID characters of "rufous hummingbirds", as well as "Ruby-throated and its look-alikes," covered in the first article.
 
Donna L. Dittmann & Steven W. Cardiff
435 Pecan Drive, St. Gabriel, LA 70776
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posted 18February2000