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Have you ever had one of those moments when you look at a word that you use and write/type all the time and it just doesn't seem to be spelled correctly? Funny how once you get derailed thinking it isn't right, you are stuck on that path. This can happen in birding when you stop and take a good look at common birds. Red-winged Blackbird is among the species that might confound you, particularly in the western U.S., where we have to contend with the very similar Tricolored Blackbird and extensive subspecific variation in Red-wingeds.
Virtually no one gets fooled by an adult male Red-winged Blackbird, except in west where the potential for Tricolored Blackbird and "Bicolored" Blackbird come into play. Even a non-birder can accurately describe one for you. I saw this black bird with red on its wing. To which you might respond: "Strangely enough, it's called Red-winged Blackbird."
However, immature male Red-winged Blackbirds and females of all ages might be confused with a variety of species, even themselves. Their general pattern–brown and streaky–often causes those seeing a female Red-winged for the first time to think that they are looking at some sort of sparrow.
With experience, these smaller, browner, heavily-streaked blackbirds, which don't look much like blackbirds at all, become readily recognizeable. Red-winged Blackbird is a widespread and conspicuous species across most of North America. And yet, if you haven't spent some time combing through blackbird flocks and familiarizing yourself with the plumage variations in this species, it can come up and bite you. For the purposes of this article, I'll focus mostly on female types and some of the variation you might see in first-spring males.
Let's start with females. At all ages, female Red-winged Blackbirds can be described as dark brown and buffy and heavily streaked, with adults being a bit warmer in tone and more colorful on the scapulars and coverts, while immatures are generally duller overall and are sometimes colder in tone. It is important to note that subspecific variation and potential geographical variation in molt patterns (Unitt 2004) need to be taken into consideration as one attempts to age female Red-winged Blackbirds and differentiate them from Tricolored Blackbirds.
Here's where the trouble starts. If you look at the illustrations in popular field guides, adult female Tricolored Blackbirds are, in my opinion, often depicted as being a bit more streaky than they look in life. Further, they are described as being "colder" and more ashy and grayish in coloration and the illustrations normally show them to have a whitish or pale gray supercilium, while female Red-wingeds–both adults and immatures–are shown with warmer buffy supercilia.
So, if you happen onto a female-type Red-winged Blackbird that looks colder and grayer and/or shows a whitish or gray supercilium, you might reasonably conclude that it's a Tricolored based on what you find in your field guide. Not necessarily. The photos below show a grayish presumed second-year female Red-winged Blackbird, first by itself and compared to adult female Tricolored Blackbirds, then side-by-side with a more colorful and buffy-faced adult female Red-winged.
Historically, it was thought that no prealternate molt occurred in Red-winged Blackbirds. However, during research conducted in Quebec 1979-1981 some degree of prealternate molt was noted in 86% of second-year (SY) females, 69% of after second-year (ASY) females, and 79% of SY males (Greenwood, Weatherhead, and Titman 1983). Conversely, Unitt (2004) noted that he found no "signficant" evidence of prealternate molt during his examination of 600 Red-winged and Tricolored Blackbird specimens; all the Red-wingeds examined by Unitt were of western subspecies, thus he attributed fall to spring changes in appearance to feather wear and subspecific variation.
Though seemingly less-confusing than females, first-spring male Red-winged Blackbirds may also exhibit variations in appearance that raise questions. After hatch-year males typically show red or orange epaulets in flight, but the red/orange is often not visible when they are perched or feeding on the ground. There may be significant variation in the amount of black seen on first-spring males, which is likely attributable to the extent of wear and starting condition of feathers acquired during the previous fall molt (A. Jaramillo pers. comm.). Jaramillo further suggested that differences in the timing or extent of prealternate molt are unlikely–to the extent that spring molt occurs in western populations. Hence, he concluded that it is the starting point or condition of feathers acquired during a hatch-year male's near complete fall molt (first prebasic/preformative) and the wear on those feathers that produces the variations one sees in first-spring males. All sources cited agree that there is essentially no prealternate molt in male Red-wingeds that are ASY or older, thus subsequent prebasic molts and feather wear produce the variations one sees in the appearance of males ASY and older.
This piece is not intended to be the last word on the plumage variation within Red-winged or Tricolored Blackbirds, just a contribution to an ongoing discussion. As Unitt (2000) suggests, the more you look, the more variation you'll see. For the most detailed coverage of this topic, the sources listed below are all recommended reading. In preparing this short photo essay, I sent my images to Peter Pyle and Alvaro Jaramillo, who were both extremely helpful in confirming the ages of the birds in those photos and directing me to authoritative papers on this topic.
Greenwood, H., P. J. Weatherhead, and R. D. Titman. 1983. A new age and sex-specific molt scheme for the Red-winged Blackbird. Condor 85:194-105.
Pyle, P. 1997. Identification Guide to North American Birds. Slate Creek Press, Bolinas, CA.
Unitt, P. 2000. Focus on Red-winged and Tricolored Blackbirds. http://www.sdnhm.org/archive/research/birdatlas/focus/blkbirds.html
Unitt, P. 2004. Featured Photo: Effect of plumage wear on the identification of female Red-winged and Tricolored Blackbirds. Western Birds 35:228-231
Photo Credits: Unless otherwise indicated, all Red-winged Blackbird images and the photo of the juvenile Tricolored Blackbird were taken by David Irons. The other Tricolored Blackbird images were provided by Scott Carpenter.