They’ll Take Two in the Bush – Crows and Ravens Show Patience

We live in an “act now!” world that frequently tests us, luring us with temptations and encouraging us to indulge. We may clearly see the importance of living within our budget yet still be dazzled by the shiny appeal of that new sports car; we may strongly believe in the benefits of a healthy diet yet still be weakened with lust for that large slab of double chocolate cake.

Nevertheless, we do sometimes succeed in delaying immediate gratification for the sake of something better in the future, in remembering those clichés about “good things come to those who wait” that our parents and grandparents inflicted on us. Undoubtedly, this is something we’re able to achieve because we’re humans, because we can be goal-directed and can prevail over our impulses, because we are more than unthinking animals who are captives to their immediate needs. Right?

Not so fast.

It is true that many animals seem unable to defer gratification, with prior experiments showing that animals such as rats, pigeons and chickens will rarely choose a delayed food reward over an immediate one, even if the delayed reward is much more attractive and the delay is only a few seconds. (From an evolutionary standpoint, this sort of impatience may make a lot of sense when an animal faces competition and future opportunities for food are unknown. “Life is uncertain, have dessert first!”)

To date, the major exception has appeared to be in primates: chimpanzees, bonobos, rhesus macaques and capuchin monkeys have demonstrated that they can wait for up to five minutes or so if that enables them to obtain a desirable food reward – a level of performance comparable to that of humans. (Interestingly, tests have shown that we humans seem to be much better at deferring money rewards than food rewards. Perhaps this, too, has a basis in natural selection, as food has been obviously always been an imperative, whereas money has existed for only an evolutionary blink of the eye.)

Also, while all of this might lead one to conclude that the ability to delay gratification lies solely within the province of humans and our closest relatives, it now turns out that corvids, the famously smart bird family (see prior AnimalWise posts here and here and here and here) that includes ravens and crows, may be every bit as patient.

When's dinner going to be ready? (from Wikipedia, photo credit: Cj005257)

As described in a paper published last week in Biology Letters, a team led by Valérie Dufour of the University of Strasbourg recently found that crows (Corvus corone) and ravens (Corvus corax) are able to tolerate delays of over five minutes in order to obtain a better reward, and that they may use the same sort of tactics to distract themselves while they wait as humans do.

In this study, six crows and six ravens were first trained to exchange tokens for food rewards, and then were given a series of “delayed exchange” tests. In each test, a bird would be handed an initial piece of food, which it could either eat immediately or, upon receipt of a signal after a designated waiting period, exchange for a more a desirable reward that it could see throughout the testing period. If the bird ate the initial reward or tried to exchange it too early, the test would end, but if it waited until the proper signal after the waiting period had elapsed – success, a better reward!

The researchers ran the tests with different types of reward (which they labeled as low-, medium- and high-quality) and with varying waiting periods (from 2 to 640 seconds).

Not surprisingly, the birds were generally more willing to exchange for the most highly preferred rewards and, as the following graphic illustrates, had a harder time as the delay period increased (with both crows and ravens maxing out at 320 seconds, or slightly over five minutes):

Interestingly, when the birds had to wait 20 seconds or longer before being able to exchange, they usually placed the “reward in the hand” on the ground and/or cached it in nearby crevices. The researchers believed this to be a distractive strategy, as “[t]hese behaviours probably alleviate the cost of waiting: not having to hold the food distracts the bird’s attention from it.”

As someone who routinely has to put snack food out of reach or even out of sight in order to prevent Homer Simpson-like devouring, this explanation makes a lot of sense to me. (For those of you who would prefer a more uplifting example of a strategy for avoiding temptation, I invite you to think about Ulysses having himself lashed to his ship’s mast so that he can safely listen to the songs of the Sirens.)

In any event, delaying gratification is significant because it involves, on some level, making a judgment about the future and the likelihood of achieving a prospective reward. While it’s not clear whether this entails a full “sense of self,” it is worth (re)noting that corvids are one of the few animals that have demonstrated the ability to recognize themselves in mirrors, a cognitive test that’s often used to measure whether an animal has at least rudimentary self-awareness.

Once again, corvids are no bird brains!

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ResearchBlogging.orgDufour V, Wascher CA, Braun A, Miller R, & Bugnyar T (2011). Corvids can decide if a future exchange is worth waiting for. Biology letters PMID: 21920957.

Rosati, A., Stevens, J., Hare, B., & Hauser, M. (2007). The Evolutionary Origins of Human Patience: Temporal Preferences in Chimpanzees, Bonobos, and Human Adults Current Biology, 17 (19), 1663-1668 DOI: 10.1016/j.cub.2007.08.033.

Heilbronner, S., & Platt, M. (2007). Animal Cognition: Time Flies When Chimps Are Having Fun Current Biology, 17 (23) DOI: 10.1016/j.cub.2007.10.012.

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Reconciling and Reassuring Ravens

Welcome to the elaborate, conflict-laden world of raven (Corvus corax) social dynamics!

Expanding on prior research demonstrating that ravens sometimes console fellow ravens who’ve been victims of aggression, researchers have now found that ravens who’ve been in conflicts often reconcile with their former opponents, the first time this behavior has been seen in birds.

Reconciling Ravens

In a study published this year in PloS ONE1, University of Vienna biologists Orlaith Fraser and Thomas Bugnyar found that reconciliation behavior does indeed occur between ravens who’ve had conflicts, particularly when the participants share a valuable relationship. While this sort of post-conflict kiss-and-make-up behavior is believed to play an important role in reducing stress and repairing relationships in primates and certain other mammals, it hadn’t been found in prior studies of birds, leading researchers to hypothesize that perhaps birds use different strategies to maintain social harmony or that reconciliation isn’t so important for birds, as their most important relationships are their pair bonds with mates, where they may be able to avoid significant conflicts in the first place.

Will we fight again? Nevermore! (photo credit: Audubon Guides)

Fraser and Bugnyar studied seven captive sub-adult ravens (who were too young to have formed pair bonds) for 13 months, measuring their behavior after a total of 197 aggressive conflicts (defined as incidents involving hitting, chasing or forced retreat). They then documented “affiliative behavior” (friendly interactions involving contact sitting, preening, beak-to-beak or beak-to-body touching) after each conflict, and compared it to the behavior occurring during neutral periods when no aggression had taken place.

They found that reconciliation (friendly contact occurring within 10 minutes of the end of the conflict) occurred after 37 of 197 conflicts and, in a significant majority of the cases, friendly interactions took place more quickly after a conflict than during the matched control period. Moreover, birds who were related or in “high value relationships” (pairs who had previously been observed to preen or sit in contact with one another) were more likely to reconcile. Interestingly, neither the sex-combination of the opponents nor the intensity of the conflict (measured by whether the birds hit each other and how many times a bird was chased or forced to retreat) impacted the likelihood of reconciliation.

The researchers did note that the behavior of ravens in the wild might differ from those in captivity, and that additional study would be needed to determine whether other factors, such as a history of food sharing, might also impact reconciliation behavior.

This study is significant in that it suggests that, through a convergent process and despite very different evolutionary histories, ravens have developed conflict resolution strategies that are similar to those employed by primates, reconciling with each other to preserve valuable relationships and reduce the chance of further discord.

Reassuring Ravens

This 2011 reconciliation research follows closely on the heels of a comparably-structured study2 that Fraser and Bugnyar published in 2010, also in PLoS ONE, establishing that ravens may possess a sense of empathy (yet another trait once thought to belong to humans alone, at least before evidence of empathy began turning up in primates and other animals).

In the 2010 study, Fraser and Bugnyar attempted to measure whether “bystander” ravens (those who’d witnessed but not been involved in an aggressive conflict) would console the conflict victim through “affiliations” (the same sort of friendly behavior – contact sitting, preening, beak-to-beak or beak-to-body touching – as was measured in the more recent “reconciliation” study).

Don't worry, you're much better looking than he is... (photo credit: pdphoto.org)

This time, they studied 11 sub-adult and two adult ravens raised in captivity, reviewing behavior after a total of 152 conflicts and in matching control periods and finding that both spontaneous and solicited (that is, initiated by the victim) bystander affiliations were likely to occur after conflicts.

More specifically, they found that unsolicited bystander affiliations were more likely to occur after more intense conflicts as well as when the ravens were related or shared valuable relationships, factors which suggested to the researchers that the affiliations served a distress-alleviating, or consoling, function. Also, the bystanders generally had stronger ties to the victims than to the aggressors, leading the researchers to conclude that it was unlikely that the bystanders were either acting as proxies for the aggressor to try to repair relationship between the combatants or trying to protect themselves from redirected attacks from the victims.

Based on these findings, Fraser and Bugnyar concluded that the best explanation for the bystanders’ unsolicited friendly behavior was that they were acting to console and alleviate the distress of the victims. The summarized the significance of this as follows:

Consolation is a particularly interesting interaction because it implies a cognitively demanding degree of empathy, known in humans as ‘sympathetic concern’. In order for a bystander to console a victim, they must first recognize that the victim is distressed and then act appropriately to alleviate that distress, requiring a sensitivity to the emotional needs of others previously attributed only to humans.

While the researchers noted some caveats, including the fact that study didn’t attempt to record vocalizations and that research on ravens in the wild was still necessary, they concluded that “the findings of this study … suggest that ravens may be responsive to the emotional needs of others.”

So, before you leave, here’s a multiple choice test regarding the moral of this story:

  1. Ravens are super smart, just like crows, nutcrackers, magpies and other corvids.
  2. We keep finding more and more ways in which other animals are able to do “uniquely human” things.
  3. If you plan on having an argument with a raven, you should make sure you bring all your raven buddies with you for support.
  4. All of the above.

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1Fraser, O., & Bugnyar, T. (2011). Ravens Reconcile after Aggressive Conflicts with Valuable Partners PLoS ONE, 6 (3) DOI: 10.1371/journal.pone.0018118.

2Fraser, O., & Bugnyar, T. (2010). Do Ravens Show Consolation? Responses to Distressed Others PLoS ONE, 5 (5) DOI: 10.1371/journal.pone.0010605.

Something to Crow About

Some of you may be aware that crows (who are corvids, like magpies and Clark’s Nutcrackers) are excellent problem solvers and that they are one of the few birds known to engage in tool use.

While there have been a variety of popular press articles describing tool use by New Caledonian crows, in this post I wanted to showcase a few videos that demonstrate visually just how impressive these crows are.

The first video features a New Caledonian crow creating a bent wire hook to fish out a food treat after realizing that a straight piece of wire won’t do the trick. Check it out; it’s pretty incredible:

In a second demonstration of cognitive abilities, the crow employs a sequence of three tools to obtain food reward – using a short stick to withdraw a medium-length stick, using the medium-length stick to obtain a long stick, and then using the long stick to reach the food. As the video notes, this is the first time a non-human animal with no explicit training has been observed using three different tools in the correct sequence to achieve a goal. Again, the video illustrates this feat quite nicely:

Finally, a recent Wired1 article, together with accompanying video, features a New Caledonian crow finding a novel use for a tool, poking a rubber spider. This sort of flexible tool use is quite rare, and crows are the first non-mammals who have demonstrated that they can use a single tool in multiple ways. Here’s the video:

I love how the crow gingerly pokes at the rubber spider and then jumps back – talk about a a familiar looking reaction!

For more information and videos relating to tool usage by New Caledonian crows, you can explore the tool use website2 of the Behavioural Ecology Research Group at the University of Oxford.

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1Wired, “Clever Crows Use Tools in New Way,” January 5, 2011.

2Visited on July 11, 2011.

Memory Superstar Eats Like a Bird

How has your memory been lately? You’ve been a little absent-minded, haven’t you? (Your keys are on the dining room table, right where you left them.)

If you don’t have a border collie to help you remember things, you may want to see if there are any Clark’s Nutcrackers in the neighborhood.

Clark's Nutcracker thinking about eating 30,000 pine nuts (photo: US Fish & Wildlife Service)

Clark’s Nutcrackers are medium-sized birds in the corvid family (the same family as jays, crows and ravens) that live in the Western United States and that rely on their memory to relocate stored food during the long winter months.  Every year, they can harvest more than 30,000 seeds from pine cones, which they then hide in thousands of separate places within a 15 mile or so radius.

Their memories for these locations are pretty incredible.  As one researcher, Brett Gibson, described it in a ScienceDaily1 article:

Nutcrackers are almost exclusively dependent upon cache recovery for their survival so if they don’t remember where they’ve made those caches, then they are in trouble. During winter, their cache locations are covered with snow so many of the small local features in the landscape during fall are no longer available to them. What’s clear is that they are using spatial memory to recover these caches. They are remembering these caches based on landmarks and other features of the terrain.

Another biologist, Russell Balda, who has studied Nutcrackers for a number of decades, is even more effusive in National Wildlife2 magazine:

How these birds find their caches looked like an incredible feat when we began studying them. We soon found out that the Clark’s nutcracker is the spatial memory superstar of the avian world, and possibly of the vertebrate world.

These two articles note that there is still some uncertainty about exactly how the Nutcracker is able to have such an astonishingly good memory. Regardless of how they do it, though, I think we all can be impressed by – and a little jealous of – these birds and their brains.

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1ScienceDaily, “Researcher Uncovering Mysteries Of Memory By Studying Clever Bird,” October 12, 2006.

2National Wildlife, “THE BIRD THAT NEVER FORGETS – The unassuming Clark’s nutcracker has one of the most remarkable memories in the animal kingdom,” October 1, 2000.

A Reflection of Intelligence?

What is it that makes us most “human,” distinguishing us from other animals?

One common response is that we have a sense of self, an ability to recognize ourselves as being separate and distinct from other individuals. Thus, when I look in the mirror, I know that I am looking at myself and not a dashingly handsome stranger. You know this as well; when you gaze in the mirror, you realize that the incredibly attractive person peering back is you!

How about other animals? They don’t “get” mirrors, do they? When they look at mirrors, don’t they either stare blankly or, at best, act as if they have seen another animal? (Hey, what’s that other beast doing on my turf? I wonder if it’s friendly….) Right?

Wrong.

Increasingly, we are finding that the answer is that other animals know exactly who is staring back at them.

First, we found out that certain great apes, like chimpanzees, can recognize themselves in mirrors. Ok, we all know that primates are smart; I’ll buy that. Then, it was bottlenose dolphins. All right, Flipper was pretty darned smart, plus dolphins have those big melon-shaped heads. I suppose that makes sense. Next, Asian elephants. Really? That’s sounds a bit odd. They do have those big eyes, but still…. I guess if you say so. Most recently, birds. Hey, now, wait a minute!

That’s right, magpies are the newest – and only non-mammal – member of the mirror self-recognition club.

Magpies with colored stickers recognize themselves in the mirror (photo credit: Helmut Prior, Goethe University)

As published in PLoS Biology1, researcher Helmut Prior and his colleagues affixed a red, yellow or black mark to feathers on the throats of five magpies (the black marks were basically a “control”: since they were the same color as the surrounding feathers they were essentially invisible to the magpies, thereby allowing the researchers to see whether any magpie behavior during the tests was the result of feeling, rather than seeing, the marks). The colored spots were positioned so that they could not be seen by the magpies unless they were looking in a mirror. When the researchers added a mirror to the cage, certain of the magpies noticed the colored spots in the mirrors and displayed “mark-directed” behavior, swiping at the marks with their beaks or scratching at them with their feet, and then checking in the mirror to determine whether they had successfully removed them. The magpies did not attempt to remove the black spots, which they couldn’t see in the mirror. Here’s a YouTube video of one of the magpies during the testing:

Also, you can read nice summaries of the research and mirror self-recognition testing in ScienceNOW2 and NewScientist3 online magazines.

This research is particularly notable given the differences between the neural anatomy of birds and mammals. Science Daily4 describes the significance:

These findings not only indicate that non-mammalian species can engage in self-recognition behaviour, but they also show that self-recognition can occur in species without a neocortex. This area is thought to be crucial to self-recognition in mammals, and its absence in this case suggests that higher cognitive skills can develop independently along separate evolutionary lines.

Mammals and birds have developed vastly different brain structures, and future studies will be able to further examine how these structures converge to produce similar cognitive abilities.

So, the magpie, lacking a neorcortex area in its brain and with an evolutionary history that diverged from ours 300 million years ago, shares our ability to look into a mirror and see itself.

The point here is not that birds can think like humans – they undoubtedly think like birds. Rather, the lesson is that we need to be very careful in labeling ourselves as special, as having exclusive abilities and intellectual talents. The more we study other animals, the more have found – and the more we will continue to find – how much we have in common, how much we share. Increasingly, I think we will find that our claims regarding uniquely human abilities are just not true, that they are simply smoke and mirrors.

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1Prior, H., Schwarz, A., & Güntürkün, O. (2008). Mirror-Induced Behavior in the Magpie (Pica pica): Evidence of Self-Recognition PLoS Biology, 6 (8) DOI: 10.1371/journal.pbio.0060202.

2ScienceNOW, “The Magpie in the Mirror,” August 19, 2008.

3NewScientist, “Mirror test shows magpies aren’t so bird-brained,” August 19, 2008.

4ScienceDaily, “Mirror Self-Recognition In Magpie Birds,” August 19, 2008.

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