Category Archives: Jay behavior

November 12, 2022 · 7:40 am

How corvids mimic human speech

If you’ve spent much time watching corvids in person or online, chances are you’ve come across one doing a Fred Armisen-level impression of something else. Perhaps it was the Steller’s jay in your backyard tricking you into thinking there was a red-tailed hawk soaring overhead, or maybe you remember the trash talking American crow that invited itself to an Oregon elementary school and delighted children with some crass language. That corvids, like some parrots, starlings, bowerbirds, etc., can mimic is well understood, but have you ever wondered why? Why can a bird talk like a person but a chimpanzee, an animal who shares 98% of our DNA, cannot? The answer boils down to three things: vocal anatomy, the brain, and behavior.

In humans, as with virtually all other terrestrial vertebrates, sound is produced in the larynx aka the voice box. As air passes through the larynx it vibrates the vocal cords, producing sounds. Across different species this system is enhanced or reduced, resulting in the roar of a lion, the grunt of an alligator or that conversation you wish you could have avoided with your coworker. While birds also have a larynx, it doesn’t produce sound. Instead, birds (well, most birds) have a wholly unique structure called the syrinx which sits not at the top of the trachea as the larynx does, but at the bottom, right at the bronchial split. This unique forking anatomy allows some birds to lateralize their sounds, meaning making different sounds on the left or right side, sometimes even at the same time! The repertoire of parrots is further enhanced by their fleshy (for a bird) tongue, which can manipulate air flow and produce more human-like speech.1 It’s this level of vocal complexity and control that possess birds with the incredible vocal range we hear, whether they use it for mimicry or not. In fact, despite this potential, most songbirds do not mimic, and actually cannot learn new songs after their first year of life.

But while the syrinx explains why some birds can produce human speech sounds, it doesn’t explain why our closest primate relatives cannot, especially given the similarities of their voice box with our own. That’s where the brain comes in. While non-human primates have the correct hardware in their vocal tracts2, they’re missing the technology they need in their brains.3 Specially, in the cortical association areas in the neocortex (the part of the brain that’s responsible for our higher-order behaviors). They simply don’t have the neurological control required to mimic human speech (though they do mimic us in other ways). So why do birds?

Unlike in primates, vocal mimicry is a cornerstone of communication and signaling in certain birds. Whether they’re using it to advertise their quality as a potential mate, territory defense, or as a way to bond with partners or group mates, mimicry plays a key role in engaging with those around them. Though the specifics of that engagement may not always be clear. For example, despite persistent online assertions that Steller’s jays mimic hawks either to warn of their presence or to scare competitors, there’s zero evidence in support of either of these. In fact, a study from 2017 found that wild jays almost never do it when predators or competitors are around, and instead do it most often at the beginning of the breeding season in front of their mate.4 Which is probably for the best. After all, if corvids chose to really make a habitat of using mimicry to trick other animals we’d likely find ourselves at the top of their target list.

Literature cited
1. Beckers G, Nelson B, and Suthers R. 2004. Vocal-tract filtering by lingual articulation in a parrot. Current Biology 14: P1592-1597
2. W. Tecumseh Fitch, de Boar B. Mathus N, Ghazanfar A. 2017. Monkey vocal tracts are speech ready. Science Advances 2: DOI: 10.1126/sciadv.1600723
3. Dunn J and Smaers J. 2018. Neural Correlates of Vocal Repertoire in Primates. Frontiers: https://doi.org/10.3389/fnins.2018.00
4. Tippin T. 2017. Propensity of predator mimicry in wild Steller’s jays. Humboldt State University, MS thesis

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Filed under Birding, Crow curiosities, Jay behavior, Ravens, Vocalizations

October 19, 2018 · 8:36 am

You need to know more about jay spit

Look, I’m a reasonable person.  I know what you’re thinking.

“Literally never has it occurred to me I might know too little about jay spit.”

But here’s the thing: it’s actually super interesting and you really can’t understand Canada jays without knowing about their saliva.  It would be like trying to understand the internet without cat videos-you just can’t do it.  So trust me when I tell you this is the information you didn’t know you needed.

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In the early 1960’s Walter Brock was examining Canada jay corpses when he discovered that they have massive salivary glands on par with the ones found in woodpeckers.1 Such generously sized glands are found in no other songbird.  Furthermore, like the woodpeckers, it’s not just that Canada jays make a lot of saliva, but they make a lot of sticky saliva.  At the time this discovery was made, it was already known that the enlarged glands of woodpeckers served to allow for a foraging tactic called “tongue probing” where, like anteaters, the birds use their long sticky tongues to extract food from narrow crevices.  Although Canada jays don’t have especially long tongues, the ability to tongue probe seemed the most parsimonious explanation for this strange adaptation, and Brock suggested that this strategy may actually be the key to the jays’ winter survival.  A study a few years later examining their foraging behavior revealed that they don’t feed in this manner, however.  They feed more or less the same way the other corvids do.2  It seems instead, that it’s what they do with the food after that’s different.

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Rather than using their copious amounts of weird, sticky spit for acquiring food, it’s used for depositing it.  If you watch a jay closely after it’s got a bit of food you’ll notice it seems to have missed Emily Post’s memo about chewing with your mouth closed. Over the course of a few seconds you’ll see the food peek out from the bill as the bird moves it around inside its mouth.

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This jay picked up this bit of food about 60sec before this photo was taken.  Now it’s working it around with its tongue, coating it in sticky saliva.

Once sufficiently spit coated, the bird will deposit the food blob (called a bolus) onto the foliage or trunk of a tree.  No matter the material or angle, once the spit dries the food is safely secured come hell or high-water.  Because these caches are pretty small there’s little fear that many will be found.  More importantly, by stashing food high in the trees instead of burying them into the ground like many other cache-dependent corvids do, Canada jays can thrive in areas that receive much heavier snowfall, allowing them the title of the most northern residing jay in North America.

A cached cranberry
A cached blueberry
Look at all that spit!
A cached grub

Here’s where it all really comes together though.  If you’ve seen me write about Canada jays before you’ll have noticed that it’s almost inevitable that I’ll use the phrase “Cute little faces” at some point to describe them.  But have you ever wondered why? Why do they have such cute little faces?  While jays do feed more or less in the same way as other corvids the one exception is that they don’t hammer at objects.  If you’re ever given a crow or a Steller’s an unshelled peanut you’ll know exactly the motion I mean. Without the need the hammer objects, or dig holes for burying food, Canada jays don’t need the heavy bills their cousins do.2  Instead they have the blunt little bill that helps give them their characteristic baby-faced look.  So not only is their spit responsible for their ability to tough it out in some of the harshest winter environments this continent offers, but it also means they get to look super cute while doing it.

So like I said, you don’t really know Canada jays until you know a thing or two about their spit.

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Literature cited

  1.  Brock WJ. (1961). Salivary glands in the gray jay (Perisoreus). The Auk 78: 355-365
  2. Dow DD. (1965). The role of saliva i food storage by the gray jay.  The Auk 82: 139-154

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Filed under Birding, Canada jays, Corvid trivia, Diet, Field work, Jay behavior, Science

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June 3, 2015 · 2:42 pm

Jays do those sassy peanut moves for good reason

After I lay down my handful of un-shelled peanuts it’s only a matter of minutes before I can hear the “thwap!” as the steller’s jay hits the cable wire that runs above my balcony’s railing.  It balances there for a moment before descending onto the pile I’ve offered it.  Quickly, and with obvious purpose, it springs down the railing and picks up a nut.  Its mohawk feathers bounce as it snaps and cocks its head around in various direction.  After only a few seconds, I hear the sound of rejection; the distinct hollow tap as the nut is returned to the railing.   The jay repeats the same process with two more nuts before abruptly flying off with one that, to my eyes, appeared identical to the first two.

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Certainly most manner of corvids engage in some kind of choosy behavior though I don’t think any of them go about it with as much frenetic spunk as jays do.  So the questions arise: Why are they being so picky?  What do they know about the rejected nuts that my eyes can’t see?

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According to a new study1, Mexican jays are actually ‘weighing’ nuts during this process.  By using specialized slow motion cameras, researchers showed that those snappy head movements are actually a way for the birds to get a tactile feel for the the nut’s weight and listen to the sound the peanuts makes as it rattles in its shell.  By providing nuts that were visually similar but different in mass, the researchers were able to show that jays could consistently select nuts with the most nutmeat density.  A further test showed that large shells that were altered to contain only one nut were typically selected first, only be be rejected, while single nut shells were accepted.  This suggests that jays either have a sense for how much nut should weigh (and thus reject nuts that contain less than they should) or that the correlation between hollow sounds and nut density lead to the ability to choose denser nuts.

So the next time your visiting jay delights you with its sassy head snaps remember; it may simply be amusing to you but for jays, it’s an impressive product of evolution that helps keep them alive.

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Literature cited:

1) Piotr G. Jablonski, Sang-im Lee, Elzbieta Fuszara, Maciej Fuszara, Choongwon Jeong, Won Young Lee. Proximate mechanisms of detecting nut properties in a wild population of Mexican Jays (Aphelocoma ultramarina). Journal of Ornithology, 2015

 

 

 

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Filed under Crow behavior, Crow life history, Jay behavior, New Research

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