Tag Archives: crow behavior

Crow curiosities: Do crows play and why?

A few years ago, on a mildly windy day, I watched a group of crows line up on the top of a building and then take turns flying off into the draft before letting it gently return them back to the rooftop to do it all over again.  This continued for at least ten minutes before I had to bid my feathered friends adieu and go to work.  Last summer, I watched two juveniles perch on a cable wire that ran from the power lines down to the ground at a steep incline.  While one of the kids was minding its own business the other snuck up and pecked and pulled its sibling’s tail until the sibling lost its balance on the crooked wire and was forced to fly to a higher perch.  Then the mischievous, ah hem, ‘pecker’ followed its sibling to the higher perch and started again. And every winter without fail, at least one person will send me the video of the snowboarding Russian hooded crow or the barrel rolling crow or the crows having a snowball fight.  Ok, so that last one isn’t real, but with all the other videos of crows at play it certainly seems like it’s only a matter of time before they start hocking little crow-sized snowballs at each other.  With all these videos and stories comes the inevitable question: Are corvids having as much fun as it looks like and, if not, what are they doing?

rolling
For scientists, this question is inherently difficult to answer.  There’s the obvious part where it still remains impossible to ask animals how they feel about their activities, but at an even more fundamental level is the question of:  how do we define play?  Play, as all things in science do, requires a very specific definition that may or may not depart from how we use the word in everyday language.  The most widely referred to definition is the following very dry and jargony sentence:  ‘…all motor activity performed postnatally that appears purposeless, in which motor patterns from other contexts may often be used in modified forms or altered sequencing’1.  And with that, what I can only imagine must be one of the most fun things on the planet to study suddenly becomes sleep-inducingly boring and the humor of the picture below is no longer confined to biologists.

wildlife bioFor now, let’s just focus on the part that said “…activities that appear purposeless.”  That leaves scientists with a different problem; how do we define ‘purposeless’ (i.e do you mean right now, or indefinitely? What if it has a purpose but I just don’t know what it is?), and therefore, how do we even identify when animals are playing and when they’re not.  Can you see the big circular rabbit hole we’ve gotten ourselves into?  Since I think most people use the catch-all definition from Potter Stewart and simply say that you know it when you see it, it can be difficult to empathize with why play has been such a difficult behavior for scientists to say a whole lot about.  Now that I hope I’ve given you some insight into why this is a difficult subject to study and thus, in many ways remains mysterious, let’s get to the fun part of talking about what we do know.

So far, observations of play in birds is limited to corvids, parrots, hornbills and babblers, reaching a grand total of about 25 species2.  To put that in perspective, there are ~10,500 species of birds in the world, making it an incredibly rare behavior among birds, and emphasizing the awesomeness of getting to observe it in our own backyards here in the PNW.

Although the snowboarding crow is probably the instance of crow play that gets the most attention, there’s actually 7 kinds of play that researchers have documented3.  Maybe I’ll try and publish my observation of the bickering crow kids, but for now, irritating-your-siblings-play is not one of them.  Here are the big 7:

  • Object play (manipulating things for no reason)
  • Play caching (hiding inedible objects)
  • Flight play (random aerial acrobatics)
  • Bath play (more activity in water than necessary to get clean)
  • Sliding down inclines (snowboarding, sledding, body sliding)
  • Hanging (hanging off branches but not to obtain food)
  • Vocal play (you know how kids go through that phase when they talk to themselves a lot? The crow version of that.)
A crow just hanging out

A crow just hanging out

So what are we to make of seeing ravens hanging, apparently joyfully, from the ends of buoyant branches in our yards or magpies playing tug of war with an otherwise ordinary twig or crows doing elaborate aerial maneuvers for no obvious reason?

Young crows playing tug of war. Photo c/o Bob Armstrong

Young crows playing tug of war. Photo c/o Bob Armstrong. (The white eye of the bird on the left is not from disease or injury, but is the protective nicitating membrane that many animals have, in case you were wondering.)

Let’s start with the conventional wisdom that everyone grows up hearing: Animals play to practice skills they need to be successful later in life.  Cats play with strings to hone attack skills, dogs wrestle to practice fighting skills their wolf ancestors would have needed as adults, etc.  The problem with this wisdom is that despite all the intuitive sense it makes it turns out it’s not very…true. In mammals, it has been shown over and over again to be unsupported.  In birds it hasn’t been looked at as extensively, and there’s at least one exception I know of that showed  ravens play cache (hide things) to evaluate competitors so that they know who is most likely to steal their cache once the stakes are raised and they’re actually hiding food4.

Other then that, the vast majority of data across both birds and mammals have shown that animals who play most often or most fiercely are no better hunters or fighters later in life than their peers.  Same goes for the studies that have compared animals that are allowed to play with those who were not5.  No difference.  So is it as easy as saying crows play just because it’s fun?  Well the problem with that is that play can be risky. Playful, distracted kids are often snatched up by predators or accidentally killed by a miscalculation of their environment.  With the level of risk that’s involved it seems unlikely it’s not doing anything for them. To make matters more complicated, although animals don’t seem to be better at the skills they appeared to be practicing, some studies show that they do seem to be better off overall.  In mammals we’ve seen that they’re more successful parents and have longer life expectancies6.  So what might be the adaptive value of fun?

Although there’s still much to be learned as far as testing play in corvids, right now I’m inclined to agree with play researcher Lynda Sharpe, who wrote a piece on this topic for Scientific American which I encourage everyone to check out.  Stress is in no way unique to humans, and it can be as debilitating and deadly for animals as it is to us.  Play is a great way for animals to hone their stress response so they’re less high strung as adults7.  Not to mention the complex, stimulating nature of play helps the brain grow8.  So why do crows play?  Learning about their peers, gaining new experiences in a low risk way, honing their stress response, and growing their big brains all seem like a good excuse to have a bit of fun to me.

Literature cited

1. Bekoff, M. and Byers, J.A. (1981) A critical reanalysis of the ontogeny of mammalian social and locomotor play.  An ethological hornet’s nest.  Behavioral Development, The Bielefeld Interdisciplinary Project.  pp296-337.  Cambridge University Press.

2. Diamond, J, and Bond, A.B. (2003) A comparative analysis of social play in birds.  Behaviour 140: 1091-1115

3. Heinrich, B. and Smolker, R. Play in common raves.  In: Animal Play: Evolutionary, Comparative and Ecological Perspectives.  Ed: Bekoff, M and Byers, J.A. Cambridge University Press

4.  Bugnyar, T., Schwab, C., Schloegl, C., Kortschal, K., and Heinrich, B.  (2007).  Ravens judge competitors through experience with play caching.  Current Biology 17: 1804-1808.

5. Thomas, E. & Schaller, F. 1954. Das Spiel der optisch isolierten Kasper-Hauser-Katze. Naturwissenschaften, 41, 557-558. Reprinted and translated in: Evolution of play behaviour. 1978. (Ed. by D. Muller-Schwarze.) Stroudsburg, PA: Dowden, Hutchinson & Ross.

6. Cameron, E.Z., Linklater, W.L., Stafford, K.J. & Minot, E.O. 2008. Maternal investment results in better foal condition through increased play behaviour in horses. Animal Behaviour, 76, 1511-1518.

7. Meaney, M.J., Mitchell, J.B., Aitken, D.H. & Bhatnagar, S. 1991. The effects of neonatal handling on the development of the adrenocortical response to stress: implications for neuropathology and cognitive deficits in later life. Psychoneuroendocrinology, 16, 85-103.

8. Ferchmin, P. A. & Eterovic, V. A. 1982. Play stimulated by environmental complexity alters the brain and improves learning abilities in rodents, primates and possibly humans. Behavioral and Brain Sciences, 5, 164-165.

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Filed under Being a scientist, Crow behavior, Crow curiosities

Reaching the limits of crow intelligence

When I was in college it became a joke among my friends and I that they would greet or bid me farewell with the following phrase “I believe in crow intelligence.”  Even as an undergrad, my passion for crow behavior and cognition was evident to my friends and family and I relished the emerging data demonstrating that this relative underdog was far exceeding our expectations of what an animal, especially a bird, could do.  While I still carry this phrase as a mantra in my research, it’s something I’ve also grown cautious to keep in check.  I’ll come back to this point in a minute, but for now let me rather crudely transition to some exciting new research.

The fantastic Alex Taylor and his group at Auckland University have once again dazzled us with another one of their eloquent studies on the New Caledonian crows.  This time they were looking at yet another aspect of crow’s learning intelligence: the ability to observe cause and effect and exercise a new behavioral pattern i.e causal intervention.  Essentially the researchers presented both the crows and two year old children with cylinder that, when hit with a block, would reward them with food.  The subjects were first exposed to the set up by baiting the block with food, thereby  demonstrating that, when moved in an effort to reach the bait food, the block would drop and release even more food via hitting the cylinder.  Babies quickly learned how to use an unbaited block provided in a new location to access the food hidden by the cylinder, but the crows failed to make the cause and effect connection.

The researchers were apt to point out that while this failure provides a fascinating insight into the evolution of causal reasoning, it does not negate the ways in which these animals remain exceptional in this respect as well.  Indeed, crows outperform children in some aspects of causal reasoning as demonstrated by the Aesop’s Fable experiments they conducted looking at object discrimination.

For me, it also provides one other important reminder: that crows are not feathered humans.  Reflecting on my earlier anecdote about my iconic catch phrase, something I’ve had to come to terms with as a graduate student is recognizing my own bias regarding these animals.  Occasionally, I find myself truly disappointed by results like the aforementioned one.  Perhaps it’s an all-American love for the underdog, or a hope that if only people understood how smart these animals are they would show them more respect.  Whatever the reason, an important area of growth for me has been acknowledging  my desire to continuing showing that these animals are exceptional and being aware of when or how that might be affecting my interpretation of my results.  This is indeed what it means to be a scientist.  Even when I have a my civilian hat on, accepting that crows are not simply feathered humans is, I think, an important part of truly embracing the natural world for what it is: a rich source of both diversity and overlap all of which deserve our admiration and preservation.

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Filed under Crow behavior, crow intelligence, Crow life history

The many sounds of crow, including the jaws theme

I am constantly fascinated by the vocal repertoire of crows.  They produce over 20 calls, but I would venture a guess that for most people (I being one of them) the vast majority of those sounds are too subtle to distinguish between.  As I hear it, there are four majors “classes” of call that are easy to differentiate, even for a completely novice birder.  Those are: The classic ‘caw’, the harsh ‘scold’, the female courting ‘rattle/knock’ call, and the juvenile begging sound.  To make up the rest of the over 20 sounds, they use a combo of caws, clicks, coos, grunts and rattles.  While more has been decoded than I offer here, there is still much that remains a mystery.  Take for example their scold call.

Me getting yelled at by a Raven in Yellowstone that wanted a treat NOW!

Me, getting yelled at by a raven in Yellowstone that wanted a treat NOW!

Stimulus days featuring either our dead crow or our dead crow+the hawk consistently draw the largest number of birds.  In fact based on last year’s data, the dead crow+hawk stimulus draws the greatest numbers of birds by a large margin.  That’s not a huge surprise since hawks are a primary predator and responding very strongly to an obvious kill would provide a safety mechanism to the ‘neighborhood’.  Needless to say, with few exception once the first bird comes across this scene it alarm calls (scolds) and either very quickly or over a few minutes will draw a crowd of 10-30 birds.  It can certainly be more or less but somewhere in that range is most typical in my experience.  Now, none of this is particularly interesting.  What’s interesting is what happens the next day.  As a reminder, all our stimulus trials feature one of the known dangers paired with a person.  In the case of the dead crow+hawk this person is standing 2m away from the stuffed birds.  In half my trials I send this person out the next day and in the other half they get sent out a week later.  This is to test for any “guilty by association” inferences the birds are making about these people simply because they were near a known threat.  To my elation I’ve found that many birds do indeed respond to these people when they see them in the future.  While that’s certainly cool in and of itself, what makes it interesting from the perspective of their calls is that although their alarm call in this instance does not sound different to me, they almost never draw the crowds the initial stimulus day does.  It’s almost as if the hawk or dead crow is a neighborhood problem but a dangerous person is only the territory holder’s problem.  Is the caller advertising this distinction and intentionally not drawing in the other birds or are the others making that choice themselves?  I have no idea.  But there’s no arguing that there’s a level of complexity there worth investigating.

As for the story on my Jaws loving bird.  This afternoon I was returning to a field site I had, just the previous day, tested the stimulus I described above on.  While I was walking through the woods on my way there I noticed a shadow occasionally passing above me.  Finally I saw my stalker: A crow who I can only assume had spotted me and was hoping I’d offer some food before we actually arrived at the now tainted feeding site.  Once we arrived I threw my food out and, unsurprisingly, was not greeted by eager feeding.  Instead the bird merely perched in the tree and stared wishfully at the food it was too nervous to eat.   After a few minutes I started to hear an inexplicable noise.  A very low duh-nuh.  Duh-nuh.  The field site is located on the edge of a residential street and at first I assumed it was some kids, maybe just playing or perhaps intentionally trying to mess with me.  It was clearly the intro to the Jaws theme song.  But the more I listened, I realized there were no kids around and the sound was coming from the wrong direction to be made my a person.  With some careful watching I realized that, although I could not perceive it to be moving its bill, my perching crow bowed its head in perfect unison with the sound.  It became clear it was the sound’s author.  In all my time watching these birds I have never heard anything like it.  Have you?  You can listen to it here, but be warned it’s pretty quiet so turn your sound up.

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Filed under Crow life history

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