Tag Archives: Crow facts

Crow curiosities: can crows see UV?

Recently, a marvelous set of blue crow photos from Carl Bergstrom had the internet’s corvid fans doing a collective double take. In addressing what could be responsible for such spectacularly odd images, many people’s first instinct was to wonder if these photos might be revealing the hidden ultra-violet lives of crows. After all, as a group, passerines (aka songbirds, of which crows are part of) are well known for their abilities to express themselves and see beyond the visual spectrum available to people. But while, “can crows see in UV? Is their perception of the feathers adorning their flock mates different from our own?,” feel like simple enough questions, a google search after their answers results in an almost unprecedented silence from the otherwise vast body of crow knowledge that exists beyond your search bar. Sure, you can find the occasional popular science article that talks about the visual systems of birds and maybe includes a photo of a crow, but these articles never provide citations and most speak simply in generalizations about passerines, not about crows specifically. The reason for this knowledge gap is that while the visual systems of birds is generally well studied, there are over 10,000 species of birds and not all of them can be the darling of every field of research. So while crows take a disproportionate share of our scientific attention, relative to many other species, not much has actually been done on their visual systems; what does exist is spread out and sometimes hard to find. But this is a question that comes up time and time again so let’s take a moment to harness what has been done, and offer the best possible answers to these questions that science currently has to offer.

Before we get to the heart of our questions though, let’s take a beat to review the more technical aspects of vision, and why our visual experience of the world is different from our dogs’ or possibly crows’. Vertebrate eyes work fundamentally via the same 5 step process: Step 1) light enters eye through pupil, Step 2) the cornea bends the light that passes through the pupil, Step 3) the light then passes through the lens which focuses it on the retina, Step 4) rods and cones of retina detect light and color and, Step 5) cells in retina convert this into impulses which go to brain. But while the general process is conserved across most species, the details of each of these steps can vary in life altering ways. Crucial to this discussion is that fourth step that involves the rods (which are motion sensitive light detectors) and the cones (which are contrast sensitive color detectors). Depending on the classes of cones a species possess, an animal can be either dichromatic (most mammals), trichromatic (primates and marsupials), or tetrachromatic (birds and reptiles), which translates to different levels of color vision. 1 While we are able to detect red, green and blue light, most birds have a fourth cone that allows them to more acutely detect short wavelength colors near the ultraviolet range. The ability to simply detect UV isn’t enough though (in fact humans are sensitive to UV light), you must also have the ability to transmit that part of the spectrum. While our eyes filter it out, rendering it invisible to us, birds have special oil droplets in their cones that allow for the passage of UV light, while limiting its damage.2 Among birds, that 4th cone (called the short-wave sensitive 1 or SWS1) can be further divided into two variants: the violent-sensitive variant (VS birds) or the ultra-violet sensitive (UVS birds) variant. Without getting any more technical, suffice it to say that UVS birds have a much keener visual experience of the UV spectrum, relative to VS birds, though both can detect UV light.3

The function of this “enhanced” vision is many fold.4 For one, it allows for greater contrast of the environment, rendering what may look to our eyes as a flat wall of green vegetation, as a much more dynamic plane, enhancing a bird’s ability to fly through dense foliage. Like insects, UV sensitivity is also important among many types of nectarivorous (nectar drinking) and frugivorous (fruit-eating) birds. Many fruits, for example, are coated in a UV-reflecting waxy substance that helps advertise their availability to would be seed dispersing birds. And finally, descriptive UV patterns in feathers opens an entire world of visual signaling that is otherwise completely hidden from us. Given the ways we might image crows would benefit from exploiting any one of these possibilities, it makes sense that they would possess the kind of rich UV experience that many other birds are known for.

Which brings us, finally, to the rub. While it’s true that most passerines are what we call UVS birds, corvids, like flycatchers and most raptors, are VS birds, meaning their visual system is biased toward the violet-spectrum and they are not considered especially sensitive to UV light.3,5 The low UV-detection abilities of corvids and many raptors, appears to offer a lifeline to smaller passerines, which exploit these visual differences in their plumage, allowing them to remain conspicuous to potential mates, while staying inconspicuous to their potential predators.6 Given this finding, we would expect crows not to, for example, show a great deal of UV detail in their feathers, and the research seems to bear this out. A study of large-billed crows found them to be so weakly iridescent, that the authors proposed their violet-blues hues may simply be an artifact of chance, and play no functional role.7 Likewise, unlike many other passerines, crows don’t seem to communicate aspects of their identify via secret codes in their feathers. A 2007 study, for example, confirmed that American crows, fish crows, and Chihuahuan ravens are sexually monochromatic from an avian visual perspective, meaning there’s no UV signaling of “male” or “female” hidden from us in their feathers.8 These birds were among only 14, of the 166 North American passerines sampled, for which this was true.

Despite these findings though, the role of UV in the lives of crows and other corvids hasn’t been rendered completely immaterial. When presented against high contrast backdrops (green foliage), fish crows are more adept at picking out UV reflecting berries than matte black Vaccinum berries. On the other hand, when both are presented in front of a backdrop that offers no contrasting advantage to the UV reflecting fruit (sandy backdrops) they pick out both berries equally. And while the UV spectrum may not be super useful to crows for coding information, that doesn’t mean the feathers of corvids don’t carry any weight. Common magpies, for example, convey all sorts of information from sex to age to territory status in their iridescent tail feathers.8 Taken together, these findings seems to suggest that there is a lot more to unpack with respect to the role of UV in the lives of corvids than, well, meets the eye, and species-specific studies may be necessary to fully parse the potential nuance.

In the mean time, while the errant photo of a blue crow may be eye catching, it’s probably not revealing an otherwise visually hidden secret, like that time a ghost showed up in the background of your vacation photo. Instead, blue crows are probably just an artifact of the photographer’s white balance gone awry in the golden hues of a fine day.

Literature cited

  1. Bowmaker JK. 1998. Evolution of colour vision in vertebrates. Eye 12, 541–547
  2. Lind O, Mitkus M, Olsson P, Kelber A. 2014 Ultraviolet vision in birds: the importance of transparent eye media. Proc. R. Soc. B 281: 20132209.
  3. Ödeen A, Håstad O & Alström P. 2011. Evolution of ultraviolet vision in the largest avian radiation – the passerines. BMC Evol Biol 11: 313.
  4. Withgott J. 2000. Taking a Bird’s-Eye View…in the UV: Recent studies reveal a surprising new picture of how birds see the world. BioScience 50: 854–859.
  5. Brecht KF, Nieder A. 2020. Parting self from others: Individual and self-recognition in birds. Neuroscience & Biobehavioral Reviews 116: 99-108.
  6. Håstad O, Victorsson J, Ödeen A. 2005. Differences in color vision make passerines less conspicuous in the eyes of their predators. Proceedings of the National Academy of Sciences 102: 6391-6394.
  7. Lee E, Miyazaki J, Yoshioka S, Lee H, Sugita S. 2012. The weak iridescent feather color in the Jungle Crow Corvus macrorhynchos. Ornithol Sci 11: 59–64.
  8. Muir DE. 2007. Avian Visual Perspective on Plumage Coloration Confirms Rarity of Sexually Monochromatic North American Passerines. The Auk 124: 155–161.
  9. Nam HY, Lee S, Lee J, Choi C, and Choe JC. 2016. Multiple Structural Colors of the Plumage Reflect Age, Sex, and Territory Ownership in the Eurasian Magpie Pica pica. Acta Ornithologica 5: 83-92.

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Why crows sunbathe

With its bill agape, I watch as the crow fans out awkwardly across the cedar shingles. Pressing the camera to my face I snap a couple photos, pleased to finally capture on film a moment I so often encounter in the field.  Unlike the crow, who’s keeping a watchful eye on the sky, I’m completely taken with my admittedly creepy behavior.  Until, of course, I hear the stiff “Excuse me, can I ask what you’re doing?” from the driver’s window as the homeowner’s minivan pulls up behind me.

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Fortunately for me, crow curiosity isn’t hard to come by and quickly the homeowner is as taken with watching this bird as I am.  “So, what is it doing up there?  I see them like this on my roof all the time” he asks after I give him my credentials.  It is a rather odd sight.  It’s nearly 90˚ and the crows is sitting in direct sunlight, mouth open, head cocked and wings outstretched like it’s injured.  Rather than escaping to shade, it’s joined by its fledgling and together they bake their bodies in the hot sun for a few minutes before gathering themselves and carrying on down to the grass to forage.

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Although the specifics can vary slightly, this general kind of posture can be observed across hundreds of bird species, even those you might not expect to have much opportunity for it like owls.  Often it’s used to dry wet feathers or warm up on a crisp winter morning but, given that they do it even when it modestly heat stresses them, it must have some other physiological benefits beside thermoregulation.

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There are a handful of other reasons that birds may sunbathe, but the big picture is that applying intense heat to feathers is critical to maintaining them in good condition.  For example, sunlight exposure has been shown to suppress feather degradation caused by the bacteria Bacillus licheniformis 1.  Heat also helps control ectopatasites, possibly by making them more mobile and easier for birds to remove2.  Lastly, sunning may relieve discomfort caused by molting and promote vitamin synthesis3.

So, far from being a signal of distress or heat exhaustion, observing this posture in crows is like watching them ruffle around in a puddle. It’s a routine, and important part of their self care regimen. Plus, everyone knows a few minutes in the sun just plain feels nice.

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Photo c/o Kathy Brown.  Find more of her great photos on Instagram @kat2brown

Literature cited

1. Saranathan, V., and Burtt, E.H. Jr. (2007).  Sunlight on feathers inhibits feather-degrading bacteria.  The Wilson Journal of Ornithology 119: 239-245

2. Blem, C.R., and Blem, L.B. (1993).  Do Swallows sunbathe to control ectoparasites? An experimental test.  The Condor 95: 728-730

3. Potter, E.F., and Hauser, D.C. (1974) Relationship of anting and sunbathing to molting in wild birds.  The Auk 91: 537-563

 

 

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Filed under Crow behavior, Crow curiosities, Crow disease

Why the crow smiles

There’s hardly a corvid species that doesn’t strike me as beautiful but there’s only one that’s always struck me as particularly gleeful.  Looking at the New Caledonian crow it’s evident there’s something different about the shape and proportions of its bill. It’s a bit shorter and more blunt, and it lacks the obvious downward curve of a typical crow bill, with lower mandible actually curving slightly up. Put together, these features appear to give it the perpetual grin that trademarks this species.  I’ve joked that this must be because they’re always feeling very pleased with themselves for being so smart, and thanks to new research, I’ve come to learn my joke had it backwards.

By using tomography scans, Hiroshi Matsui and his team were able to compare the shape and structure of the NC crow’s bill with that of its close relatives. Their conclusion, which they report in the March issue of Scientific Reports, is that this shape makes the handling and manufacturing of tools easier. Looking at photos of the birds in action, it feels intuitive that the more exaggerated curve of a raven or American crow bill would have a hard time achieving the dexterity that NC crows need to use their stick and hook tools.

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Given this new research it’s time to amend my joke. It’s not that NC crows grin because they’re smart, they’re smart because they grin.

Literature cited

  1.  Matsui, H., Hunt, G., Oberhofer, K., Ogihara, N., McGowen, K., Mithraratne, K., Yamasaki, T., Grey, R., and Izawa, E. 2016.  Adaptive bill morphology for enhanced tool manipulation in New Caledonian crows.  Scientific Reports 6. doi:10.1038/srep22776

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Filed under Crow behavior, crow intelligence, Crow life history, New Research

5 corvid facts that will surprise you

With all the online crow trivia listicles that are already floating around it can be hard to come up with tidbits that are both factual and interesting.   I was up the the challenge though and am hoping I found at least one thing every reader didn’t know.  Let me know how I did in the comments section!

 1.   Avocados are toxic to crows.1

Well, really avocados are toxic to most birds, and many other kinds of domestic animals.  Avocados contain a molecule called persin, which the plant produces as a fungicide.  In birds, it can cause damage to the heart tissues, difficulty breathing, lethargy or even death.  The resplendent quetzal is a rare exception in that it can not only tolerate avocados, but is considered a crucial seed distributor of the plant.  So next time you’re considering sharing your Chipotle leftovers, make sure you didn’t order extra guac.

2.   Scavenging accounts for very little of a crow’s diet2

Scavenging, meaning the consumption of dead plant or animals material, is a crucial part of our ecosystem that is commonly the recipient of unfair prejudice. American crows often get thrown in with this lot, and while there wouldn’t be anything gross or insulting about this if it were true, it simply isn’t.  Whether you’re in the city or the wildlands, scavenging and active predation account for only a minority of a crow’s diet.  The bulk of their daily meal is made of human refuse, invertebrates and worms.  In the cities, about 85% of their diet is human refuse, whereas in exurban and wildland areas human refuse and invertebrates account for roughly equal proportions of their daily food (about 35% each).

Photo: W. Perry Conway/CORBIS

This scene is not as common as many people think! Photo: W. Perry Conway/CORBIS

3.  There’s only three places with no native corvids3

New Zealand, the southern part of South America and the poles (ok so I guess technically 4 if you want to be a stickler about it).  Why this is remains largely mysterious, but it probably has to do with where and how these birds radiated out from their ancestral origins.

Global corvid distribution. They'll be our avian overlords soon enough I'm sure.

Global corvid distribution. They’ll be our avian overlords soon enough I’m sure.

4.  They have some of the best spatial memory of any animal4

Every year Clark’s nutcrackers and pinyon jays store tens of thousands of seeds to sustain them through the lean winter months.  If they fail to retrieve enough they’ll perish, so a good spatial memory can literally be the difference between life and death.  To deal with this mental load, these two species (and other food caching birds) have a huge hippocampus relative to the rest of their brain.  With the spatial memory part of their brain super charged they’re able to retrieve 20,000-30,000 seeds with 90% accuracy or better.  I can’t usually retrieve my cell phone what that kind of accuracy so I certainly tip my hat to them!

Photo: Minnesota Birder

Clark’s nutcracker.  Photo: Minnesota Birder

5.  They account for the largest songbird in the world.5

The common raven is marginally the largest songbird of the world with a 4.9ft wing span and weighing in at up to 4.5lbs.   An extremely close second is the thick-billed raven, which is native Ethiopia and has limited range in some surrounding countries.  In fact, the two are so close in size that there are conflicting reports of which is bigger depending which publication you look at3,5.  Scientists finally resolved this dispute, however, and came to the consensus that the common raven is larger for the 2009 publication of the Handbook of the Birds of the World.*

Photo: Ignacio Yufera

Thick billed raven.  Photo: Ignacio Yufera

*This section has been updated from a pervious version which incorrectly stated that the thick-billed raven was larger.

Literature cited

  1.  http://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants/avocado
  2. Marzluff, J.M., McGowen, K.J., Roarke, D. and Knight, R.L.  2001.  Causes and consequences of expanding American crow populations.  in Avian ecology and conservation in an urbanizing world (J.M. Marzluff, R. Bowmanm and R Donelly, eds).  Kluwer academic Press, norwell, Ma.
  3. Madge, S. and Burn, H. 1999.  Crows and jays.  Princeton, New Jersey: Princeton University Press 1999.
  4. Marzluff, J.M. and Angell, T.  2005.  In the company of crows and ravens.  Yale University Press.
  5. dos Anjos, L., Debus, S., Madge, S., & Marzluff, J. (2009). Family Corvidae (crows). In J. del Hoyo, A. Elliot, & D. A. Christie (Eds.), Handbook of the birds of the world (Vol. 14, pp. 494e641). Barcelona, Spain: Lynx Edicions.

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Filed under Corvid trivia, Just for fun

Baby crow detective work

By now, most of us have come across these images of  “baby crows” so often it induces more of a yawn than a fit of aggravation.
Image-1If, somehow, these images are new to you feel free to check out my post fully debunking them, as I will not dedicate any further time to them here.   But there’s a new photo circulating social media, and it makes for a much more compelling crow doppelganger;

baby crow
You’ve got three, black, altricial baby birds in a nest and really, they’re not terribly un-crow like.   It doesn’t make you a complete crow rookie to make this mistake, but there are some key things wrong here.  And this is the moment where, as a scientist, these photos elevate from being simply another source of annoying misinformation (which, they are) to the kind detective work that childhood doctor visits fostered a deep love for.  Because, not unlike my favorite activity in the Highlights magazines I anxiously parsed through in those waiting rooms, there are 4 things that are different between these two photos and it’s up to you to find them.  So take a minute and see what jumps out at you….

Crows_v_no crows
Figured it out (or given up)?  The first thing to know is that all bird species are very specific in terms of both nest materials and nest construction.  Sure, some birds can happily use some ribbon in place of straw (like orioles) or build nests in old shoes just as easily as in gutters (like bewick’s wrens) but the basic style is always the same.  Robins will always use mud as a binder and bushtit nests will always look like cozy sleeping bags made of moss.  Knowing that, the material used in the nest on the right should jump out as a red flag.  Of course you’ll find crow nests with a bit of string, fabric or grass (especially for lining) but the bulk of the nest is always made of pinky-wide sticks.   Really, you need look no further at this point to know immediately that the photo on the right is an impostor but let’s keep going because it’s fun.

Next let’s look at the babies themselves, which is where the three remaining differences are.  Two of them are color-coded, did you catch them?  Ah yes, gape and eye color.  See that brightly colored area on the corner of the bird’s developing beak?  That’s called the gape, and the bright color that flashes when they open their mouths is a powerful signal that tells parents to “insert food here”.  Crows have bright pink gapes, whereas these other birds have yellow gapes.  Our other color coded giveaway is the eyes.  Granted the lighting is not great, but it’s clear that the crows on the left have light blue eyes whereas these other birds have dark eyes.  In some species of crow the babies are born with brown eyes that turn blue as they age, but such is not the case with our American crows and you can expect that nestlings will always have blue eyes.  The last clue, which takes more expert level knowledge to notice, is the bill shape.  The birds on the right have a slightly more embellished curve to the bill than a typical crow chick.

The final mystery, of course, is what the birds on the right actually are.  Unfortunately, I failed to track down the original poster, but as best I can tell they’re black drongo chicks.  Black drongos are members of the drongo family (Dicruridae) and are native to Southern and Eastern Asia.  Here’s another photo I found that looks consistent with the previous one.  If any drongo experts read this blog though and want to correct me, I’d love to hear from you!

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Filed under Birding, Crow life history

Corvid trivia quiz!

How much trivia do you know about our favorite family of birds?  Head on over to Buzzfeed where I’ve created a quiz to test your knowledge.  When you’re done, feel free to come back to this page and scroll past the corvid photos for more information, citations/links, and to post your score in the comments section.  Can anyone get 100%???

TAKE ME TO THE QUIZ

peeking
ready crow
congrats

1.  Were you surprised to learn that they are songbirds?  Indeed, corvids have impressive vocal repertoires and are among the minority of songbirds that can learn new sounds throughout their lives1.

2.  I’ve railed (get it?!) about this in a previous post but until this image stops circulating my Facebook feed I’ll take every opportunity show folks what real baby crows look like.

3.  The life span of different crow species (Fish, American, Hawaiian and Northwestern) is similar and generally they top out at between 14-24 years.  Ravens on the other hand, usually only make it to 13, though in captivity they can live 40-80 years1.

4.  It’s a common misconception that humans can get WNV  from touching a crow, but there’s no evidence for it according to the CDC.  It’s an understandable rumor, however, considering that corvids are an ideal host for this virus, something I’ve talk about in a previous post.  Humans on the other hand, are considered dead-end hosts, meaning the virus can’t proliferate in our bodies (though that doesn’t preclude it from making some of us very sick).  The real transmission culprits are mosquitoes.

5.  Learn more about the ‘Alala at American Bird Conservancy.

6.  Currently there are actually 7, not 6, ravens at the Tower (you know how those Brits are about their spares!).  According to Historic Royal Palaces they eat 170 g of raw meat a day, plus bird biscuits soaked in blood.   Yum!

7.  Originally, I was going to make the whole quiz just a corvid ID quiz, but I decided that might get old quickly.  Still wanted to get at least one question in there!

8.  Again, ‘murder’ and ‘unkindness’ are not words you’ll typically see in scientific writing (apart from, perhaps, as a means to a pithy article title).  But they make good trivia questions nonetheless.  Fun fact: Company is the term for parrots and deceit is for lapwings.

9.  John Marzluff discusses nearly all these behaviors in his books, so I’ll make thing easy and simply refer you to In the Company of Crows and Ravens.

10. New Caledonian crows are well know for their puzzle solving prowess, but I’m sure ‘007’ completing this task had his researchers especially delighted.  To see footage of 007 at work check out this video.

11. Keeping crows, like hunting them, is regulated under both federal and state laws.  To learn more about the rules regulating crows read my previous post on the Portland crow poisoning.

12. I recently acquired Crows and Jays by Madge and Burn, and recommend it to anyone who wants to become more familiar with all 120 species.

13.  See above.

14.  Part of why I wanted to create a trivia quiz is because I thought it would be a fun excuse to go hunting for a thing or two I didn’t know myself.  Jimmy’s story was exactly the kind of discovery I was hoping for.  Perhaps I’ll do a bit more digging and dedicate a whole post to it.

15.  It’s with good reason that John’s motto about crows is that “they’re little flying monkeys”.  I love this study2 and sharing its findings never gets old!  This kind of equity perception is something that’s been rarely documented outside of primates and underscores the impressive convergent evolve that’s occurred between corvids and primates.

Literature cited

1. Marzluff, J.M. and Angell, T. 2005.  In the company of crows and ravens.  Yale University Press

2. Wascher, C. F.  and Bugnyar, T. 2013.  Behavioral responses to inequity in reward distribution and working effort in crows and ravens.  Plos One: DOI: 10.1371/journal.pone.0056885

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Filed under Corvid trivia, Just for fun

Crow curiosities: who is begging in April?

Right now, in early spring, you may have noticed a crow or two fluttering their wings and making the classic “waaah, waaahhh” sound that roughly translates to “feed me, feed me”!  Although it’s tempting to think these are young crows, it’s far too early in the breeding season for fledglings to be on the loose.  So who are these juvie doppelgangers? Adult female crows.

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Begging juveniles like this one won’t be roaming around the PNW until mid June and later.

During the nest building stage you may hear females making these sounds just while on the ground foraging with their mate or while perched near the nest like this female was.  Why do they do it?  It’s essentially a way to prime the pump and remind their mate that they’re going to need to be fed once they’re saddled to the nest and can’t forage as much for themselves.  Once they are actively incubating, they’ll continue to beg only now it’s really a demand for the food they need and can’t get for themselves without risking their eggs getting too cool.  Although males will take a turn on the nest, they do not have a formal brood patch and can’t do much more than temporarily keep the eggs insulated.

Although it’s tempting, hopefully now you won’t be fooled by this April trick!

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A male returns to the nest with a bill-load of peanuts for his hungry mate.

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Best books for corvid lovers

This post was prompted by someone on my twitter feed who asked that I put together a reading list for people who want to learn more about corvids; a totally kick-ass idea if I say so myself.  The following are all the books I have read and can speak personally to, however, I’m sure there are others and I encourage folks to add them in the comments section.  As a preface, I’ll remind readers that John Marzluff is my graduate adviser, nevertheless, I assure you that I genuinely believe he is a fantastic writer and my review of his books are not inflated in the hopes of getting approval on my dissertation. 🙂  So without much further adieu, here’s a list of all the corvid books I’ve read with a brief synopsis of the material and my recommendation.

index

In the Company of Crows and Ravens by John Marzluff and Tony Angell
If watching, feeding or rehabilitating corvids is something you do in your free time, consider this your crow bible.  Curious how long crows live?  What they do as juveniles?  The sounds they make?  The ways the interact with people?  It’s all in there.  This book remains my go-to guide for general crow knowledge.  Yet, despite the fact its backbone is rigorous science, it’s written in a way that feels very easy to digest.  John and Tony wrote it with the intent that it would be for a wide audience and I think they achieved that beautifully.  After reading this book, I have no doubt you’ll have a deeper understanding for these birds, not to mention a new admiration for Tony’s artwork.  I even used one of his drawings for the book on the invitations for my wedding (with permission, of course).

raven

Dog Days Raven Nights by John and Colleen Marzluff
This is the book I most often recommend to my own friends and family.  Not because it offers superior or more easily read  information on corvids, but because this book gives you the best insight into what it really means to do fieldwork.  Nearly the entirety of the book focuses on the period of time after John and Colleen had finished their graduate work in Arizona, and were conducting a post-doctoral study on ravens with Bernd Heinrich in remote Maine.  It’s organized as a back and forth between John and Colleen, which means you get two perspectives on the raven work and Colleen’s development as a dog sledder and trainer.  As a reader, you experience what it means to completely dedicate every moment, piece of sanity, and dime you have on conducting a field experiment and you walk away with a much deeper appreciation for how difficult it is to answer questions of animal behavior.  If the human dimension of science isn’t your interest, however, fear not.  The book is still loaded with fascinating information on ravens including, in my opinion, one of John’s most important contributions which is information sharing among ravens.  An excellent read for sure.

gifts

Gifts of the Crow by John Marzluff and Tony Angell
For those looking for a more scientifically dense reading on crow behavior and neurology this is the book for you.  It doesn’t make for the lighthearted Sunday reading that ITCOCR does, but it still satisfies the trademark Marzluff style of mixing rigorous science with the anecdotal stories of crow behavior that makes us love them.  If you’ve been fascinated by the story of Gabi Mann, the little girl who feeds and gets gifts from crows, then this is the scientific background you need to see the whole picture.

mind

Mind of the Raven by Bernd Heinrich
Long before John Marzluff started writing books, his post-doc adviser, Bernd Heinrich, was already an expert at the game.  Heinrich has a reputation for being one of the most eloquent and engrossing natural history writers and it’s a reputation that’s been well earned.  Mind of the Raven is actually what initially peaked my interest in corvids, so in many ways I have this book to thank for the work I am doing now.  For anyone who lives with ravens, or simply has a fascination for them, I can’t recommend it enough.  Bernd’s writing will nurture your passion and give you the science to back up what you already know: ravens are badass, awesome animals.

planet

Crow Planet by Lyanda Lynn Haupt
Crow Planet it a book best characterized by Haupt’s journey to find curiosity and loveliness in an increasingly urban landscape where the natural world can feel further and further away.  Crows therefore, offered the perfect vehicle for looking at and appreciating what remains when the forests retreat and box stores and neighborhoods take their place.   By the author’s own admission her journey through writing Crow Planet made Haupt appreciate, “but not quite love”, crows.   Despite this, she manages to write about them with grace, and her stories will make even the biggest skeptic take another look at these animals.  Although Haupt’s background is not in science, she doesn’t omit the scientific facts, though she does take more artistic liberty when describing their antics than John or Heinrich do.  All that being said, this is an excellent book for the urban naturalist or crow watcher.

crow

Crow by Boria Sax
If you’re interested in crow mythology this is the book for you.  Sax takes you through time and space to explore the role of corvids in human myth, religion and art.    His thoroughness is without compare, but if anthropology is not your interest this book will prove taxing.  It’s one I happily keep on hand, but not one that I’ve ever had the patience to read all the way through.  Nevertheless, I probably should, since it’s chalk full of information and historical context that I would be better off knowing.

Bird brain

Bird Brain: An exploration of avian intelligence by Nathan Emery
Although not exclusively dedicated to corvids, Bird Brain, written by corvid cognition expert Dr. Nathan Emery, offers an incredible look at the minds of your favorite birds.  Although his book tackles some of the more difficult concepts of avian cognition, it feels and reads more like a coffee table book, complete with beautiful artwork, some of which was done by Emery himself.  Each chapter is themed around a particular aspect of cognition (communication, spatial memory, etc.) and walks the reader through the fundamental biological principals and samples the most interesting studies that have been done on the topic.  The book is rich with the kinds of analogies and descriptions that break through the barriers of dry scientific writing.  Perfect for the budding young scientist or the long time corvid fan.

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The wake of crows: Living and dying in shared worlds by Thom van Dooren
“Crows are among our most familiar and charismatic animals and as such there is a body of literature dedicated to them for which few other wildlife species compare. While each contributor takes a distinct perspective and harnesses different stories or features of their biology, there is perhaps nothing as unique in the body of work dedicated to crows as this book. It is neither a classic natural history book, nor a memoir of being connected to the natural world through crows. Instead, van Dooren has used crows as a loom on which to weave science and humanities together, producing a thesis of what it means to exist in our contemporary world. Central to this thesis is the question of “What else is possible?” For the traditional science and natural history reader his exploration of this seemingly familiar question will be anything but familiar. While by now, for example, we may be used to being asked to reconsider the crow as pest or bad omen, here we are asked to reconsider them systemically, and in ways that ultimately inform the reader’s ethic….It’s a unique and powerful look at what it means to live in a shared world, and asks that we reconsider our ethics in doing so. It is far from a light read, but it is one that grants the experience of expansion that curious people crave.” 

This section is apart of a larger review I wrote of The wake of crows for a contribution has been accepted for publication and will appear in a revised form (subject to input from the journal’s editor) in a book review for Oryx—The International Journal of Conservation.

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I’m sure there are many others I haven’t read which subsequently didn’t make this list.  Feel free to make recommendations in the comments section!

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Filed under Crow behavior, Crow curiosities, Crows and humans, Raven behavior, Raven intelligence

Why climate change may be deadly for crows

In general, crows love the ways that humans transform the environment.  We plow down forests and replace them with suburbia, creating a perfect mix of the occasional nesting tree and plenty of grassy yards perfect for looking for bugs.  On top of that, we litter and waste food, providing lots of additional foraging opportunities outside of our yards.  And even when we replace the forests with urban epicenters, we build towers perfect for nesting, leave out even more garbage, and make the environment less hospitable to predators.  But this climate change thing, well now we’ve gone too far. Even for crows.

Scientists know that climate change is going to be bad for lots of species, with some projections estimating that by 2050, 15-37% of species in the areas sampled will be committed to extinction if current emission trends continue1. Not all creatures will be worse off as the climate warms, however, some will do quite well.  Who are these lucky creatures you ask?  No, not beautiful sword-billed hummingbirds, or rare pygmy marmosets but…mosquitoes.

GO is a proud (albeit perhaps oblivious) participant in the #iamclimatechange campaign.

GO is a proud (albeit perhaps oblivious) participant in the #iamclimatechange campaign.

Warmer, and in some places wetter, climates are projected to not only increase mosquito numbers but, importantly, increase the incidence rate of West Nile virus2.  Crows are particularly susceptible to WNV over other non-corvids, making this especially bad news for them3.  One study showed that some regional crow populations across the US declined 45% since WNV was first introduced in 19994. As warmer temperatures march north, scientists predict we’ll see WNV not only increasing in areas where is exists now, but spreading to northern latitudes where it may have a particularly acute effects2 (I’m talking to you, Canada!).

By extension, this is also bad news for us, since humans can also get sick from being bitten by infected mosquitoes (there is no evidence we can be infected from handling sick or dead crows, however5).  Not to mention all the other diseases mosquitoes carry that kill people and birds.  So whether you care about climate change because you care about crows, humans, or any of the other organisms that are/will be negatively affected, now is the time to do something about it.  Individuals can have profound effects by making changes in their own lives, and by putting social pressure on others to do the same.  There’s plenty of reason to be hopeful if we act!  To learn more about the #iamclimatechange campaign that GO was nice enough to participate in please check out the tumblr or facebook page.

Citations

1. Thomas, C.D., Cameron,A., Green, R.E., Bakkenes, M., Beaumont, L.J., Collingham, Y.C., Erasmus, F.N., Ferreira de Siqueira, M., Grainger, A., Hannah, L., Hufhes, L., Huntley, B., van Jaarsveld, A., Midgley, G.F., Miles, L., Ortega-Huertam, M.A., Townsend Peterson, A., Philips, O.L., and Williams, S.E. (2003) Extinction risk from climate change. Nature 427: 145-148

2. Tam, B. Y., and Tsuji, L.J.S. (2014) West Nile virus in American crows (corvus brachyrhynchos) in Canada: projecting the influences of climate change.  GeoJournal DOI 10.1007/s10708-014-9609-z

3. Yaremych, S. A., Warner, R.E., Mankin, P.C., Brawn J.D., Raim, A., & Novak, R. (2004) West Nile virus and high death rates in American crows.  Emerging Infectious Diseases, 10, 709.

4. LaDeau, S.L., Kilpatrick, A.M., and Marra, P.P. (2007) West Nile virus emergence and the large-scale declines of North American bird populations. Nature Letters. 447

5. http://www.cdc.gov/westnile/faq/deadBirds.html

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Filed under Crow disease, Crow life history, Crows and humans

My top 15 favorite crow facts

I, apparently like so many of my generation, are a sucker for insta-read lists.  Something I can crunch through in about 5min between classes.  My favorite proprietor of this content is Buzzfeed.  Although most of their lists are some kind of pop-culture reference, every once in a while I see something nature or science related and on two separate occasions have even seen posts related to crows.  Both were rather jejune.  So it seemed a perfect marriage to unite one of my favorite social media sites with some carefully selected and researched crow tidbits.   You can check out my post here on my top 15 favorite crow facts.

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Filed under Crow behavior, Crow curiosities, crow intelligence