Generally speaking, I don’t write posts advertising specific stories or news articles about my work. I figure anything going in those stories is all stuff you can get firsthand here, and of course I link to all of them on my ‘In the Media’ page so they’re never far out of reach anyway. But I wanted to put out a special post about Vicki Croke’s article for the WBUR’s The Wild Life blog. Most of the time when people write about me, the blog is a footnote, a way to learn more if you wish, but not something mentioned specifically. As a follower of this blog, I imagine you have some idea how much time and effort I put into it (as much a grad student’s life allows for it, anyway) so I was extremely flattered and honored when Vicki made the blog a focal point of the article. Given the supportive community we have built here together, I thought you especially would enjoy reading this piece. Let me know what you think of it in the comments and thank you for your continued presence here and passion for crows.
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You’re minding your own business when seemingly from out of nowhere you are, or very nearly are, struck in the back of the head by crow. It’s frightening, embarrassing, and in rare cases even painful. So what prompted this unprovoked attack?
If you were to gauge the answer based on newspaper headlines you might believe that it’s because crows are evil, vicious or otherwise hellbent on tormenting us humans. This choice of words communicates that crows are behaving as they are because they lack moral decency, which is both anthropomorphic and grossly misrepresents the biological cause of their behavior.
Rather than being a reflection of their species’ character, or The Birds come to life, crows are increasingly behaving this way right now because young crows are starting to venture out of the nest. As I’ve talked about before, it’s not unusual for baby crows (and other birds) to leave the nest while still unable to fly. Although their parents will continue to care for them after this for many months, these first couple weeks out of the nest are a particularly vulnerable time for young crows. Their parents are therefore keen to protect their offspring, and are willing to come to blows with potential predators if necessary. You may have no intention of harming or even coming near their offspring, but of course the crows have no way of assessing your intentions. You are simply a big, powerful animal that is encroaching on their young, and they are driven to scare you away. They are simply being protective parents.The tricky thing is that because we might not be expecting to encounter young crows or because they are tucked away out of sight under a bush, it may not be clear that this is the cause of their behavior. Trust me though, unless you have a history of wronging your local crows, attacks between May and September are nearly exclusively related to the protection of young. So what to do? As the kids grow up and become more independent the parents will relax. So, if possible, you can simply avoid the areas you know to be high conflict for the next couple of weeks. In fact, some newspaper outlets even make attack maps to help people navigate the streets of stressed out crow parents. If this isn’t possible, carry an umbrella or simply walk with your hand on top of your head. This may not keep them from giving you a good swoop or two, but it will generally prevent any real damage.
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!
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.
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.”
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.
Pied crow: Corvus albus
Alb means “white.” No mystery here.
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: 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.
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.
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!
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.
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.
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.
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.
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?
Many thanks to Tara for a truly interesting crow, and for agreeing to let me share Al’s story here.
- Guay, P.J., Potvin, D.A., and Robinson, R.W. 2012. Aberrations in plumage coloration in birds. Australian Field Ornithology 29: 23-30
- van Grouw, H. 2013. What colour is that bird? The causes and recognition of common colour aberrations in birds. British birds 106: 17-29
- 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.
- 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
In honor of last week’s #CrowOrNo photo, I wanted to spend some more time spotlighting a corvid perhaps less well known to my fellow North Americans, the rook (Corvus frugilegus).Among corvids, adult rooks might be one of the most unmistakable species. Their naked, chalk colored chin, lores, and bill base gives their face an appearance resembling no other bird. The grey crow, or bare-faced crow (Corvus tristis), shares a similar facial pattern but is easily distinguished by its rather blushing appearance and blue eyes. In addition, whereas the grey crow is known mainly to the peoples of Papua New Guinea, rooks have one of the widest distributions of any corvid species, breeding from Sweden all the way to China.
(Hover over tiled photos for captions)
Of course, what made last week’s #CrowOrNo submission such a challenge was that the photo was not of an adult, but rather a first year bird. With their nasal hairs intact, first-year rooks look something like a crow/raven hybrid. Although bill shape is, I think, the best tell, one other field marker to look for are their notoriously shaggy “pants” (belly and leg feathers) in contrast to crows and ravens.
The transition to bare-faced adult occurs during the bird’s first complete body molt when they’re around 10-15 months old. This process can take as little as 25 days but for most birds occurs over the course of several months1. The evolutionary reason for this loss may have something to do with their foraging habits, which consists largely of probing for worms, though this remains unclear.
Unlike many Corvus species which are more general with respect to their diet, rooks are fairly specialized to feed on the small worms that live among the roots of plants. One consequence of this diet is that there are distinct boom and bust seasons. In April and November, wet conditions make worms plentiful, but in other times of years drier conditions drive worms deeper and out of reach. Since access to food can be precarious, rooks have adopted a rather unusual incubation strategy compared to most birds. Rather that commencing incubation when the entire clutch is laid, which promotes the same hatch date, rooks start incubating the first egg as soon as it is laid. This chick is born earliest, giving it a clear advantage over its future siblings. If food becomes sparse only this chick will survive. If food remains abundant, the parents can provision enough to supply the larger, more dominant chick, and its younger siblings.2Rooks are distinct from other corvids with respect to their behavior as well. In contrast to crows or ravens, rooks are essentially non-territorial. During the non-breeding season they are most commonly found in large foraging groups (much to the chagrin of local agricultural farmers, I imagine). During the breeding season they nest in colonies, rather than individual territories, though they will defend the area around their nest and their mate as necessary. A nest is often reused by the same pair year after year until it is razed by weather, or the pair is forced for some other reason to construct a new nest. Like many other Corvus species, they maintain a socially monogamous life-long mate.3
Cognitively, rooks demonstrate many of the same skills that have brought some of their peers into the global spotlight. For example, when in the care of humans, rooks have demonstrated an astounding alacrity for tool use, though they are not known for manufacturing tools in the wild. For example, captive rooks have been shown to bend wire into hooks to extract food out of a tube like New Caledonian crows, or work together to solve problems like chimps (though unlike chimps, they do not appear to understand when cooperation is necessary or how it works).4,5
Taken together, these snippets of their biology and behavior demonstrate what unique members rooks are to the Corvus genus. I envy my counterparts across the Atlantic and Pacific and encourage them to take a second look at the rook whenever opportunities present themselves.Literature cited
1. Dunnet GM, Fordham RA, Patterson IJ. (1969). Ecological studies of the rook (Corvus frugilegus) in North-East Scotland. Proportion and distribution of young in the population. British Ecological Society 6: 459-473
2.Green P. (1996). The communal crow. BBC Wildlife 14: 30-34
3. Coombs CJF. (1960). Observations of the rook Corvus frugilegus in southwest Cornwall Ibis 102: 394-419
4. Bird CD, and Emery NJ. (2009). Insightful problem solving and creative tool modification by captive nontool-using rooks. PNAS 106: 10370-10375
5. Bugnyar T. (2008). Rooks team up to solve a problem. Current Biology 18: R530–R532
A few months ago I started a new Twitter/IG game called #CrowOrNo. This was, in part, simply a response to the awesome wave of science games across social media and wanting to be apart of that science communication effort. But I also started it because discerning these birds is just genuinely hard. Case in point, I’ve had more practice than most but even I get fooled sometimes.
One of my most popular posts is “10 corvids that don’t give a damn about your rules” which, while intentionally lacking any scientific credibility was at least supposed to be an accurate collection of corvid gifs. Turns out I goofed. Not once but twice. The original post contained these two gifs neither of which are of corvids. It took the help of an Australian birder, and a fellow corvid expert, Jennifer Campbell-Smith, for me to notice my error.
As a grad student/scientist/blogger/science communicator this is my nightmare. That I’ve put out information, even if it was supposed to be fairly non-sciencey in nature, that’s wrong. But I did.
Being a catastrophist, my first reaction is “You blew it. No one will take you seriously now. It’s over.” Needless to say, this is not a motivating feeling. It’s a ‘crawl under the covers and stop trying’ feeling, which is about the least helpful way to react to making a mistake and a reaction I would discourage in anyone else. So I’m going to take my own advice and remember that I’m a person before I’m a scientist. I’ve made, and will continue to make mistakes. The only thing I can promise is that I will be forthright in my mistakes and keep learning.
So the next time you error in #CrowOrNo, know you’re in good company. Sometimes I’m wrong too 🙂
Salutations lovely blog followers! This is just a quick note to explain my absence over the last couple of months, and invite you to see what it’s all been for.
For whatever reason (ambition, insanity, desire to please, capability, or the combinations therein) I took on a little more than I could chew this quarter. Teaching, taking courses, taking my qualifying exams, submitting a paper and, as a cherry on top, taking my general exam (i.e the dissertation proposal). I love my blog, and you folks and the aspects of crows that I can share with you are constantly on my mind. At the end of the day though, my priority is my graduate work and sometimes the blog needs to take a backseat.
I do not tell you this in the hopes you’ll understand, I tell you this because I already know you understand. But I also know you follow the blog because you are passionate about crows and to that end, I want to invite you to see the presentation of my dissertation proposal this Monday, Dec 5th.
While this talk is intended to impress my faculty committee enough that they approve me as a PhD candidate, it is given to a room of largely first year students, and is therefore designed to be inclusive of all backgrounds and knowledge levels. Crucially, this seminar is also open to the entire community, so you won’t find any awkwardness strolling in as a member of the public and not as a UW student. I hope to see you there!
For a map to Kane Hall click here.