Monthly Archives: March 2017

What’s in a (corvid) name?

Most people know various corvid species by their common names but have you ever wondered what etymologies inform their scientific names? Turns out it’s a pretty fun little exercise to find out!

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Before we get to breaking down individual corvids though, a quick word on scientific names more generally.  Scientific names always have the format: Genus species. Meaning, the first word in the name tells you what genus the plant/animal belongs to and the second tells you the species name specific to that organism. So for example crows, rooks, jackdaws and ravens are all in the same genus so their scientific names will all start with the same word: Corvus. The second word, however, will be unique to each species. This system of binomial nomenclature was first developed by Carl Linnaeus in the 1700’s.  By looking up the roots of an animal’s scientific name we can learn a thing or two about what he, (or whoever named it) was trying to highlight. Then again, sometimes they’re just fans of Beyoncé or Jonny Cash.

One more note: although scientific names are often referred to, informally, as Latin names, their roots may actually pull from many languages.  Though by far the most common languages are Latin and Greek.

As it happens, I have an old book of  root words I inherited from my late grandfather, Richard Swift. Something about having that book in my hands begged for this exploration in a way that having the breadth of the Internet at my fingertips never did. What can I say, a childhood spent in the library of my grandfather’s office has made me a sucker for old, smelly books. So let’s get started!

Common raven: Corvus corax
Common ravens are the biggest of the corvids (and in fact, the biggest of all the songbirds) so it makes sense their name might be the yardstick by which other corvids are measured. Cora literally translates to “crow, raven” so the common raven’s scientific name essentially just means raven.

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GO, the American crow

American crow: Corvus brachyrhynchos
Turning to American crows, we can see that yardstick I mentioned coming into play. Brachy means “short” and rhynch means “a beak or snout.” So the American crow’s full scientific name basically translates to the “short-beaked crow.”

junlge crow

Jungle crow, photo c/o Anne Kurasawa

Jungle crow: Corvus macrorhynchos
At this point, the meaning of the jungle crow’s name probably needs no explanation. The bird looks essentially like an American crow but with a more pronounced bill. Macr rhynch = large beak.

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Pied crow, photo c/o Frank Vassen

Pied crow: Corvus albus
Alb means “white.” No mystery here.

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House crow, photo c/o Benjamint444

House crow: Corvus splendens
Splen means “a badge or patch.” With grey sweater they sport, it’s likely the person who named them was trying to highlight this physical distinction.

thick billed raven

Thick billed raven, photo: Ignacio Yufera

Thick-billed raven: Corvus crassirostris
Sometimes, scientific names are precisely their common names. Such is the case here. Crass means “thick” and rostr means “beak.” This is a good example of where we see different languages influencing the names.  In this case, thick-billed ravens got the Latin root, whereas American and jungle crows got the Greek root for beak.

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Rook, photo c/o Pam P.

Rook: Corvus frugilegus
This one is less clear to me. Frugi means “useful, fit” and legus means “lie down; choose; or collect” depending on what language you pull from. My guess is it’s supposed to be ‘collect’ and the name refers to the more specialized bill they have for collecting insects.

Finally,

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The grey or bare-faced crow, photo c/o B.J Coates

The grey crow: Corvus tristis
Trist means “mournful; sad.” I have a feeling I know the backstory for this one but I’ll leave it to my readers to see if they can figure it out. Leave me your best explanation (made up or researched) in the comments!

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Have you ever seen a caramel crow? 

Generally, when I receive emails with the subject line “interesting crow” it’s because the author noted some peculiar or amusing crow behavior they want to share, or because they spotted an unusual looking crow due to AKD, leucism or avian pox.  Rarely, it’s for none of these reasons and is truly a horse of a different color. Or in this case, crow.


Meet Al, a hatch year American crow whose natal territory overlaps with Tara Chafe’s property. According to Tara, Al is the second bird born in the last 5 years with this kind of color abnormality. The bird that she reports is its mother is leucistic, but as you can see below, she’s not a particularly dramatic case with maybe only one or a couple more white feathers.

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Without having observed Al myself I can’t confirm any of Tara’s observations, but from her perspective, Al appears to interact normally with the other crows, and doesn’t exhibit any other health issues. In fact, the first caramel crow that Tara encountered has gone on to mate and establish a territory in a nearby neighborhood and she still occasionally encounters it.

Understandably, Tara’s question to me was “what is going on here?” and initially, though I am by no means an expert in pigmentation, I didn’t expect it would be too much work to provide her an answer.  And with that my descent began.

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It’s helpful to start by understanding what controls pigmentation in birds.  There are three different groups at play: melanins, carotenoids, and porphyrines1.  Melanin is probably the most familiar term, after all we possess a lot of it ourselves and the skin cancer melanoma is named for the melanin producing cells where it occurs.  In fact, there are three kinds of melanin: eumelanin, which controls dark browns and blacks, pheomelanin, which controls reddish hues, and neuromelanin which occurs only in the brain.  Carotenoids, on the other hand, are derived from plants and produce the red of a cardinal or the yellow of an American goldfinch.  Porphyrines, which are modified amino acids, can produce a wide variety of colors from pink to green, as observed in some of the more colorful corvids such as the Bornean green magpie and ceylon magpie.  Lastly, the structure of the feather also plays a role in color, particularly with respect to iridescence, but I’ll save that for another post.  Of most concern to us in this case is melanin, since that’s what’s controlling coloration in American crows.

Knowing this is an issue of melanin, I next wanted to identify how we might characterize this color aberration.  Older birders will describe this bird as leucistic, and historically that convention was considered accurate.  Contemporary semantics among pigmentation papers, however, have clarified leucism as a condition that “results from a complete lack of melanin from all or parts of the plumage”2,3. In other words, crows that are leucistic would be completely white in one or more feathers, which this crow is clearly not.  Without yet knowing exactly what’s going on here the more appropriate terms might be: “Schizochroism” meaning a lack of a single pigment, or “dilution” meaning an overall decrease in pigmention deposition2. A color mutation known as “brown,” meaning a qualitative reduction of melanin, has also been proposed3.

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A leucistic crow in flight

With this much information at hand, we might begin to think that this reddish/caramel colored bird has some issue with its eumelanin production that is giving way to more visible pheomelanin.  The trouble is, by all accounts crows do not produce pheomelanin3,4,5. So if crows do not produce pheomelanin what is going on here?

Fellow crow expert, and the much more knowledgeable in pigmentation than I am Dr. Jennifer Campbell-Smith, sees there being a few possible explanations.  The first is simply that we haven’t studied pigmentation across Corvus species thoroughly enough to say that crows such as American crows don’t produce pheomelanin.  After all, some Corvus species, such as the brown necked raven, certainly appear to express pheomelanin produced colors.  Perhaps American crows do produce a modest amount that has so far been difficult to detect, but is revealed in cases like this.  Alternatively, Jennifer suggests that even if American crows don’t typically produce pheomelanin they may still possess all the infrastructure for doing so. Perhaps in cases such as Al’s, the genes that regulate such production have been turned on. As an especially interesting side note, pheomelanin is a particularly energy intensive pigment to produce, and as such, there’s evidence of a correlation between larger brain sizes (including Corvus species) and low to undetectable levels of pheomelanin6.

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Brown necked raven (Corvus ruficollis) photo c/o Peter Nash

Another publication suggested that cases like Al’s are caused by incomplete oxidation of eumelanin3, but I am dubious of this paper because they claimed that corvids as a family do not produce pheomelanin, which blatantly untrue at worst or, if they meant Corvus, an egregious typo at best.

Ultimately, what I found was that rather than being a matter of a quick trip to the virtual library, an explanation for Al’s condition is currently unresolved by science.  Which is probably my favorite genera of science.  After all, what’s better as a scientist than embarking on the unknown or poorly understood?

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This week’s #CrowOrNo picture

Many thanks to Tara for a truly interesting crow, and for agreeing to let me share Al’s story here.

  1.  https://academy.allaboutbirds.org/how-birds-make-colorful-feathers/
  2. Guay, P.J., Potvin, D.A., and Robinson, R.W. 2012. Aberrations in plumage coloration in birds. Australian Field Ornithology 29: 23-30
  3. van Grouw, H. 2013. What colour is that bird? The causes and recognition of common colour aberrations in birds.  British birds 106: 17-29
  4. Lee E, Tanaka H, Wakamatsu K, Sugita S.  2009.  Melanin-based iridecent feather color in the jungle crow.  Journal of Veterinary Medical Science 71: 1261-1263.
  5. http://www.sibleyguides.com/2011/08/abnormal-coloration-in-birds-melanin-reduction/
  6. Galvan I, Moller AP.  2011.  Brain size and the expression of pheomalanin-based colour in birds.  Journal of Evolutionary Biology 24: 999-1006.  DOI:10.1111/j.1420-9101.2011.02232.x

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