Tag / signal

by Roslyn

Life imitates [filmmaking] art

Congratulations to Myra Burrell – her peacockumentary has been short-listed for the Animal Behavior Society’s film festival!

Myra, a veteran of the natural history film program at the University of Otago in New Zealand, traveled to California with me in 2010. She helped with peacock field work, capturing more females than anyone thought possible. Somehow, in the meantime, she made a movie about the birds. It’s a short film that gives you an idea about what happens on a peacock lek, from the hen’s point of view.

It’s quite an honour to be among the 6 films selected for festival screening, since they must get on the order of ~100 applicants. If Myra wins, it would be oddly fitting: a wildlife film straight out of a park that moonlights as a real Hollywood set.

You can watch “Hen’s Quest” here.

The best parts? I love the music and Myra’s cinematography. I contributed writing (including the title!) and did the artwork; Brian McGirr turned my map drawing into a fantastic animation. Good luck, Myra!

by Roslyn

Cuttlefish strike a pose for 3D camouflage

In the game of hide and seek, cuttlefish have the upper hand. These chameleons of the sea are astonishingly good at disappearing: they can instantaneously change the colour of their skin to blend in with the background, matching even the finicky details like the pattern of coloured rocks on the ocean floor.

Divers have long known that cuttlefish are masters of the 3D camouflage game, too, and new research from the Wood’s Hole Oceanographic Institute has revealed how they do it.

Alexandra Barbosa, a graduate student, and Dr. Roger Hanlon were interested in the way cuttlefish strike a pose when trying to hide. After encountering a predator, these octopus-like animals will flee among the corals, rocks and algae, and freeze with their arms contorted into shapes that mimic nearby objects – a feat made all the more impressive by the fact that cuttlefish arms can bend in any direction. Some birds and insects are also known to camouflage themselves with body posture, but few come close to cuttlefish in shape-shifting flexibility (see photos of cephalopod camouflage in the wild here).

To understand just how they do it, Barbosa and her colleagues in Dr. Hanlon’s lab presented captive cuttlefish with some highly unusual surroundings: jailbird stripes, in black and white. In response, the cuttlefish got theatrical, raising their arms roughly parallel to the angle of the stripes. And when the researchers shifted the angle of the background image, the cuttlefish stretched their arms into a new position in an attempt to stay hidden.

Cuttlefish posing on artificial backgrounds

Cuttlefish posing against different backgrounds. Modified from Barbosa et al. 2011 (see Figure 1).

Intriguingly, not all of the ten individuals tested were able to match the angle perfectly all of the time – but these quirks may not be surprising given that cuttlefish camouflage is so complex. After all, in nature cephalopods get to choose their own hiding places, a decision that might involve several different factors. According to the researchers, camouflaged cuttlefish are even known to gently wave their arms to match the movement of the underwater plants they are trying to mimic.

These results are a clear demonstration that cuttlefish use vision to guide their 3D camouflage, since the study animals matched a flat background image. Moreover, Barbosa and Hanlon have shown that shape-shifting cephalopods can easily handle scenarios that would never occur in the environment where these behaviours evolved, and adjust just as flexibly to this artificial environment as they do in their natural habitats.

Captive experiments like this are just the first step in understanding how cuttlefish use visual cues to hide, and some big questions remain. For instance, little is known about how cuttlefish can detect and match colours so well despite the fact that they are, in effect, colourblind – Hanlon has found that giant Australian cuttlefish can take on the colouration of rocks on the ocean floor even in the middle of the night.

These remarkable split-second decisions about where, and how, to hide might also help us understand something bigger. Strategic camouflage is just one aspect of the surprising intelligence of cuttlefish, which have the largest brains for a given body size of any invertebrate – these animals are also able to learn and communicate with one another at a level that rivals many land-based animals. It will be intriguing to see where hide and seek fits in to the history of cephalopod brain evolution.

Further Reading

Barbosa, A. et al. 2011. Proceedings of the Royal Society B. In press.

by Roslyn

Species of serendipity

Like most ideas, this one arrived in the shower. I needed to write a post for this week, but my list of topics was wearing thin and the weather is finally starting to get nice enough to distract me. Sure, I had a few promising ideas lined up, but they all need more time to develop. Plus I had a DVD to watch: a Nature of Things episode on serendipity in science due back at the library. Then it hit me – of course! I’ll watch the episode and then write about that.

Serendipity – supposedly one of the top ten most untranslatable words in the English language – was coined in the 1700s by Horace Walpole as a play on the tile of a Persian fairy tale. The Three Princes of Serendip takes place in Sri Lanka. It follows the adventures of three brothers exiled from the island by their father the king, in hopes that his sons might achieve a more worldly education. In the course of their travels, the princes go on to solve many mysteries – like unintentionally tracking down a lost camel on scant evidence – thanks to their sagacity and a series of lucky accidents.

Since Walpole, the word has taken on a close association with Eureka moments in science, starting with Archimedes’ famous bath. Supposedly, the ancient Greek mathematician solved the problem of measuring the volume of irregular objects after noticing how his own body displaced water in the tub.

Scientists have taken a great interest in tracking serendipity, perhaps because it seems to play a role in research success. Wikipedia has an extensive list of celebrated examples, from Viagra to chocolate chip cookies. Many have looked for ways to encourage this kind of scholarly luck. For instance, after his Nobel prize winning work on viruses, the molecular biologist Max Delbrück is perhaps best known for coming up with the principle of limited sloppiness: researchers should be careless enough that unexpected things can happen, but not so sloppy that they can’t reproduce them when they do. Alexander Fleming had this advantage when he discovered penicillin. He first noticed its antibiotic effects in a stack of dirty culture dishes that he hadn’t bothered to clean before leaving for summer vacation.

So how do people study something that is by definition rare and unusual? Psychology Today has summed up some of the latest research on luck, most of it based on surveys of people who claim to be especially serendipitous1. Not surprisingly, they are more competent, confident and willing to take risks than the rest of us. They are also more extroverted and less neurotic than most. Being born in the summer apparently helps as well – especially May.

Other advice might be more practical.

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by Roslyn

Furious about eyespots

I think I flubbed an interview this week. My supervisor Bob and I just published a paper that is getting some press, because it addresses a recent controversy about the peacock’s train1. Eager for the interview with Nature News, I wasn’t exactly prepared with good lines for the reporter to go on – and I wonder if that’s why he had to pump up our story as a “furious debate”2.

In truth, most of the “debate” played out in a flurry of news articles back in 2008. That was when Mariko Takahashi and her colleagues in Tokyo and Kanagawa published the fruits of their exhaustive 7-year study of the peafowl at the Izu Cactus Park in Shizuoka, Japan3. I’ve never met Takahashi, although I did meet her supervisor and one other player in this story at a conference back then, and all were quite friendly. But the title of Takahashi’s 2008 paper, “Peahens do not prefer peacocks with more elaborate trains” was a direct jab at an earlier one, “Peahens prefer peacocks with more elaborate trains”, by Marion Petrie in the UK4. Takahashi and her coauthors had the difficult task of proving a negative – and they did it pretty convincingly, with the aid of a much more extensive data set than anyone had gathered before with this species. The upshot? For a peacock in Japan, having a bigger train ornament doesn’t necessarily win you any favours with the ladies.

Bigger in terms of the number of eyespots visible in the ornament during courtship, that is; males have about 150 on average, each on the end of a single feather. The results of the Japanese study were in direct contradiction to Marion Petrie’s earlier work as well as some recent studies of peafowl in France suggesting that eyespot number is often correlated with male mating success4,5. What’s more, in the 1990s Petrie had confirmed the causal effect of eyespots by showing that you could alter a male’s fate just by removing about 20 of them6.

Peacock in flight

Taken at the Los Angeles Arboretum in 2009. Photo by Roslyn Dakin.

The Japanese team proposed a rather bold new hypothesis. Perhaps the cumbersome, ridiculous train ornament is obsolete – a relic of sexual selection past, no longer used by females in quite the same way as it was when it first evolved3.

This was taken up with gusto by the news media. Check out the headlines: “Peacock feathers: That’s so last year”, “Have peacock tails lost their sexual allure?”, “Peacock feathers fail to impress the ladies”. Amusingly, this last article was also published with the title, “Female peacocks not impressed by male feathers” by Discovery News7-10. Males could probably be forgiven for striking out with those elusive female peacocks, since they don’t actually exist.

Headlines aside, Takahashi’s interpretation is somewhat of a concern. Here’s why: creationists picked up on this story too11.

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by Roslyn

I can haz toxoplasmosis

In which you will learn why online cats are so attractive, and discover a new way to lose hours to the internet.

First, the cats. Charlie and I were hashing out the finer points of Facebook, memes and internet superstars, when, in frustration, I brought up his most hated animal.

“Look. Cute baby videos and LOLcats are popular because people send links to their friends. Nobody sits down and says, ‘Well it’s quarter to 10, the same time I always drink my coffee and look for the latest cute cat photos on the–’ ”

Self defeat and laughter mid-sentence, when I remembered living with my friend Jessica in Toronto. She had a brutal job in psychiatric research north of the city. After a hard day, that was exactly what she did. Nothing cheered this woman up like online cat research.

Felis catus is a polarizing species. Some people despise them. Ancient Egyptians and cat ladies have made a religion out of them. The story goes that wild cats were first domesticated in ancient Egypt for useful things like keeping rats out of grain stores and killing poisonous snakes, but this might be more myth than reality. Cats were probably kept around as tame rat-catchers much earlier, certainly before recorded history, and very likely around the beginning of agriculture itself. People were depicting cats on pottery 10,000 years ago1. Cyprus can boast the first Stone Age cat lover. A 9,500 year old burial site on the island is the earliest evidence of humans bonding with these animals, since a cat was intentionally buried alongside a human body there2. The fact that the cat was not butchered, and the inclusion of decorative seashells and stones in the grave, prove that cats had achieved cultural importance beyond their agricultural utility back then.

European wildcat

The European wildcat Felis silvestris is a close relative of the earliest domesticated species. Photo by Péter Csonka from Wikimedia Commons.

But could the cat haters be right – is there something off about feline love? After all, cats aren’t really that useful, at least not when compared to dogs. Dog people might be pleased to hear that when you consider all living and extinct canid and felid species, dogs have bigger brains than cats – probably because they tend to be the more social animals3. Indeed, dogs adapted readily in response to domestication, evolving a number of cognitive abilities that make them particularly good at understanding human gestures – much better, even, than chimpanzees4. Naïve 4-month old puppies will quickly learn what it means when a human points, without any training or close contact with humans beforehand5. Cats can do this too, but they require a lot more effort to learn how6. Dogs can detect certain forms of cancer in humans by smell, and they are often the first ones to notice that something is wrong with their owners7. I have yet to find any high profile studies on feline pathologists. Which raises the question: if cats could do it, would they care enough to try?

And in a bizarre twist, there’s reason to think that our magnetic attraction to cats might be the result of a real parasitic disease.

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by Roslyn

Identity evolves

“Everyone is special.” The paradoxical refrain of baby boomer parents to their millenial offspring is true, so long as you’re a rodent living in a large, stable group of good communicators.

I recently wrote about the phenomenon of identity signals in animals, where variable colours and patchy-looking patterns can provide signatures of individuality, much like the human face. These are not limited to the visual domain. Think of how easily you can recognize a person’s voice – even someone you don’t know very well – from just a few lines of speech, like when a celebrity turns up in an animated movie.

But I didn’t have a chance to cover the latest news on this topic. In some very plain looking rodents, we now have evidence that individuality evolves1. Some of the plainest looking critters, like the Belding’s ground squirrel shown below, have the most distinctive snarfs and grumbles – and it all has to do with the number of group-mates they typically interact with.

Belding's ground squirrel pups

Two Belding’s ground squirrel pups peek out of a burrow. Photo by Alan Vernon from Wikimedia Commons.

The new results came out this month in the high profile journal Current Biology. Previously, researchers had looked for the evolution of individuality in a handful of bird and bat species. The prior studies examined distinctiveness in the begging calls offspring make to their parents, contrasting pairs of closely-related species that vary in the number of offspring in shared “crèche” or communal nest sites2,3. But nobody had tackled the evolution of individuality in a broad context.

Until Kim Pollard, that is. Pollard, a recent PhD graduate from UCLA, and her supervisor Dan Blumstein decided to look at this question in the social marmots. You might remember Blumstein from another recent post; his interests range from mammal conservation and environmental education to the bioacoustics of movie soundtracks.

For Kim Pollard’s study of identity signalling, marmots were an ideal choice. Marmota is a large genus of 14 different species in the squirrel family, all social, and all with their own alarm calls that they use to warn neighbours and family members about nearby predators. Species like the yellow-bellied marmot and Richardson’s ground squirrel also have the ability to recognize each other based on the unique sound of these calls4,5.

Crucially for Pollard and Blumstein, social group size also varies in the genus, ranging from about 5 to 15 individuals per clan or family group. This allowed the authors to test the hypothesis that group size has been an important factor in the evolution of distinctiveness, since, as they put it, “The bigger the crowd, the more it takes to stand out.”

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by Roslyn

A case of mistaken celebrity

They all look the same to us. Celebrities, that is. And by us, I mean academics.

The proof starts with peacocks. Last fall, I was working on some measurements I took of the crest ornament in these birds. Peafowl have this funky little fan of feathers on top of their heads, and though it’s not that small in the grand scheme of fancy bird plumage ornaments, the peacock’s five centimetre crest looks a bit ridiculous next to the metre-and-a-half long train.

Why bother having a crest when you also have a big train? And why do females wear crests too? In this species, the crest appears to be the only plumage ornament shared by both sexes. Here are some of my pictures from the field, taken on the cusp of the breeding season:

Crest ornaments of male and female peafowl

Crests of (a) male and (b-c) female peafowl. Scale bars are 10 cm. Photos by Roslyn Dakin.

Over the years, I’ve measured the crests of close to 150 birds. These data lend some support to the idea that the crest is a signal of health in both males and females, although it might work in slightly different ways for the two sexes1. As you can see from the picture above, there is a lot of variation in how the crests look – and it’s mostly on the female side of the equation. Almost all adult males have tidy looking crests like the one shown in (a), but females often have crests with a lot of new feathers growing in (c). It turns out that males in better condition tend to have fuller, wider crests. The healthiest females, on the other hand, have crests that look most like those of males, with all feathers grown out to the top level (b).

The extreme variability among females leads to an additional hypothesis, and it’s one that I can’t rule out at this time. Perhaps the crest is a signal of individual identity that the birds use to sort out who’s who in their social groups – just as faces do for us. A clue that this could potentially work for peahens is that my field assistants and I can do it. Once you spend enough time hanging around with these birds, you find yourself recognizing certain females that haven’t been captured yet (and that therefore lack identifying leg bands). Your first clue? Usually a unique pattern of crest feathers.

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by Roslyn

The winning score

As Hollywood gets dolled up for the Oscars, fans at home might surprised to learn that a field biologist could tell us a thing or two about the winning films. Dan Blumstein, a behavioural ecologist who works, quite fittingly, at UCLA, is an expert on yellow-bellied marmots. He might also be the person to turn to if you want to predict the win in the “Best Original Score” category this weekend.

Although Blumstein does most of his work with wild marmots in the Rocky Mountains of Colorado, studying several facets of their behaviour and evolution, he recently published a paper on the science of movie soundtracks1. With Richard Davitian and Peter Kaye from the School of Music at Kingston University in the UK, Blumstein applied techniques from his research on marmot vocal communication to an entirely new question: why are Hollywood moviemakers so good at manipulating our emotions? The results pick up on a common theme in the way humans and other animals use sound.

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by Roslyn

Groupthink

Which animal would use Facebook most, if it could?

My poll in class last week was a popular one – a fact that I couldn’t properly enjoy, since Charlie came up with it for me in a fit of brain-dead incapacity. Charlie’s Facebook question elicited chirps of excitement, compliments and even a few drawings on the response sheets. Here are the results, ranked by favour among the students:

  • Chimpanzees: So they have opposable thumbs, and can “use the spacebar” (is this actually important in Facebook?). A number of students gave bonobos special mention, since they would probably want to keep track of all their casual sexual relationships.
  • Dolphins: Highly intelligent, social, and they might also be interested in monitoring multiple sexual conquests. Dolphins and migratory whales could use Facebook to keep in touch while roaming widely over the oceans – the long-distance relationships of the animal kingdom. For some reason, students in different tutorial groups who chose dolphins were inspired to draw them for me as well. Coincidence?
  • Parrots and other birds: Especially in species that have high levels of extra-pair paternity, birds could use Facebook as a form of mate-guarding to keep tabs on their social partner1,2. There are other reasons to think that songbirds might easily make the transition to internet gossip. Female black-capped chickadees, for instance, eavesdrop on the outcome of song contests between rival males, and use this information when deciding on a mate3.
  • Eusocial animals: Like ants or naked mole rats (the only known eusocial mammal). A couple of students also mentioned highly social meerkats, since living in groups of 10-40 individuals would require them to keep track of a lot of social information.
  • Other yappy follower-types: hyenas, seals, lemmings, and Yorkshire terriers all got a mention.

Charlie and I discussed it over dinner at the Iron Duke. My first thought went to ants, for their extreme group lifestyle. The problem is that ants don’t really care about what other ants do or think about each other. Insect sociality is all about the greater good: worker ants toil away for the colony despite having no hope of reproducing on their own. Ok, so maybe the internet isn’t conducive to real reproduction either, but ants just don’t have the ego required. Plus, as one clever student pointed out, a colony of eusocial animals are all very close genetic relatives of one another – and she tends to block family members from Facebook.

Charlie mentioned peacocks for spending so much time on courtship and preening, but I rejected that one too.

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by Roslyn

Not when cupid strikes

Raphael's The Triumph of Galatea

“Not when cupid strikes.”

That was Christine Drea’s response at the Animal Behavior meeting last summer. She had just given a talk on her latest study, showing the dramatic effects of hormonal contraception on the way lemurs communicate with the opposite sex1. I was asking her what advice she gives to women about birth control. On the 50th anniversary of the Pill, scientists like Drea were adding to the evidence that we might want to think twice about our widespread use of these drugs. The lemur research suggests that hormonal contraception could be replacing one “problem that has no name” – Betty Friedan’s idea of the dissatisfaction felt by modern women – with another2.

Like many primates, ring-tailed lemurs have a complicated system of signaling to one another through scent. Males are able to detect the sex, fertility and even the identity of a particular female by smell alone3. At first glance, the connection to humans might seem far-fetched, since our noses are pretty poor compared to other mammals. But we are relatively well-endowed when it comes to scent production: humans have more scent glands on the surface of our skin than any other primate4.

We also have some surprising olfactory abilities lurking beneath the surface. The classic example is the T-shirt test. In the 1990s, researchers at the University of Bern in Switzerland gave a group of men T-shirts to take home, with instructions to sleep and sweat in them over the next two nights5. When women were later asked to sort the dirty T-shirts based on pleasantness of smell, they did something surprising. Their rankings came down to genes: the more genetically distinct a man was from a female rater, the more she liked his scent.

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by Roslyn

Wherefore the mustache?

Ears, palms, toes, neck, and nose. In that order.

These are the grossest places for humans to have hair, according to Queen’s students. Ok, there were a few others that I didn’t mention. The upper lip, however, did not receive a single vote.

Last fall a number of men in the biology department grew competitive mustaches for “Movember” prostate cancer research fundraising. This required mass beard shaving on the first of November. Martin Mallet, known for his thick coat of fur, emphatic hand gestures and all-around intensity, suddenly transformed into a meek imposter. For the first time Martin had no probing questions for the speaker at the EEB seminar. I can’t help but wonder: if he did, would anyone have noticed?

I started to recognize Martin again when the hair on his upper lip attained visibility. Other men of Movember fared less well. It can’t be a good thing when the people who work in the same office as you don’t even notice your new, mustachioed face.

But what, if anything, is it for? My experience suggests that human facial hair serves as a male status signal. Is this why we evolved mustaches in the first place?

Inca Tern

Why do mustaches evolve? Inca tern, from Wikimedia Commons.

In class the other week we discussed Stephen Jay Gould and the trouble with adaptationism. Gould famously criticized the proliferation of sloppy adaptive reasoning in his 1979 paper “The Spandrels of San Marco and the Panglossian Paradigm“1. He took aim at scientists who apply adaptive “story-telling” to nearly anything – from the colour of our skin to the size of our noses – in an unverifiable, unfalsifiable way.

It can be easy to jump on the adaptationist bandwagon, since these stories are often quite plausible. This may have been especially true when “Spandrels” was written, due to the rise of some revolutionary ideas about how to apply evolutionary biology to the study of social behaviour. There was plenty of new research to be done. Of course, many of the people doing this research disagreed with Gould’s characterization2. At its worst, adaptationist thinking might lead to some bad science, especially when it comes to human behaviour (where confounds are especially hard to control). But speculation is a necessary part of the scientific method, and adaptive reasoning can be a good place to start.

It is worth noting that Gould’s paper has been enormously influential. “Spandrels” has been cited well over 3500 times. I’m still waiting on citation number 3 for my Master’s research.

And yet, the response of the research community to the “Spandrels” critique has largely been, “That’s well said, but let’s get back to our field work.”2 In that spirit, consider the mustache. Can we speculate about it in a reasonable way, avoiding the big adaptationist pitfalls?

First of all, is this question worth asking?

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by Roslyn

Super indelible flower colours

How do you fire a pollinator?

That was the question in last week’s Ecology, Evolution and Behaviour departmental seminar. The speaker was James Thomson, an evolutionary ecologist from the University of Toronto who specializes in the interactions between plants and their animal pollinators. His research shows that nectar-addled hummingbirds are like corporate ladder climbers. Bees, on the other hand, are always getting canned.

Pollination syndromes have been a major focus of Thomson’s work1. These are not garden ailments. “Syndrome” here refers to a suite of traits that tend to be found together, in this case because they help a plant attract a certain kind of pollinator.

Bird-pollinated flowers tend to be red and tube-shaped, producing lots of nectar but relatively little scent. Birds have sharp vision, and do not depend much on their sense of smell. Honeysuckle is an example of this type of flower – or anything that looks like a hummingbird feeder. Bee-pollinated flowers come in shades of yellow, blue, and purple, because bees cannot see the colour red. Familiar examples are sunflowers, snapdragons and wild pansies. These often have petals modified into special bee landing platforms. Flowers that specialize on birds and bees are common, but there are many other pollination syndromes. If a flower is orange-brown and smells like rot, it probably depends on carrion flies. Mammal-pollinated flowers often smell fruity, like synthetic grape flavouring.

In his talk, James Thomson reviewed a decade’s worth of work on beardtongue flowers from the genus Penstemon2. In 2007, Thomson and his collaborators used genetic analyses to build the evolutionary tree for close to 200 of the species in this group3. When flower traits were mapped on to the Penstemon family tree, interesting patterns were revealed.

First, the bird and bee pollinated species were distributed broadly throughout, implying frequent transitions between these two syndromes in the history of the Penstemon group. Like an evolutionary magnet, pollination by one type of animal or another exerts a strong pull on multiple flower traits in concert. Evolving species are drawn rapidly towards a new form, so you almost never find intermediates.

This lability or changeable nature of floral traits was not much of a surprise, but the Penstemon tree also suggested something incredible. Floral evolution was directional.

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by Roslyn

Reaching the other side, in synchrony

It’s a familiar site on campus here during the first week of class: packs of jaywalkers moving in tight co-ordination, in sync with the flow of oncoming cars. From traffic lights and power grids to stereo sound and cinema, synchrony is so common in our environment that we usually only notice it when it fails. Not so with nature: the examples of synchrony in living things tend to be much more surprising to people studying animal behaviour.

Group courtship displays are a classic example. Think of chorusing songbirds in the morning or calling frogs gathered around a pool of water at night. Readers of my blog on peacock field work might be familiar with lek-mating birds gathered around a clearing to wait for females. Peacock train displays also tend to happen in sync. One traditional explanation for these co-ordinated displays is that, by synchronizing their most conspicuous behaviour, animals might gain some protection from predation1. Another possibility is constructive interference: co-ordinated timing might allow a pair of animals to spread the message farther than either one could on its own2. Two innovative new studies on animal courtship have added to this list. The first, on firefly displays, shows that synchrony might help insects recognize members of their own species by getting rid of visual clutter.

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by Roslyn

Masters of illusion

It can be easy to see intelligence in the animals we spend a lot of time with. Everyone has their pet example, one of the most common being dogs who can anticipate the precise time of their owners’ return. But what does this really say about the mental life of dogs? Some birds are capable of even more impressive mental stunts – only they often go unnoticed in the wild. Two recent field studies in Africa and Australia provide a nice illustration. The results challenge our notion of limited animal intelligence, but as we will see, the way we interpret them might say more about our own minds than it does about the birds.

Fork-tailed drongos are masters of deception. These small, glossy black birds from southern Africa are known for their ability to mimic the calls of other bird species – much like the mockingbirds found throughout the US and parts of southern Canada. Most of the time, drongos forage alone hunting insects, but occasionally they get other animals to do the hard work for them. Drongos will follow groups of meerkats and pied-babblers – mammals and birds known for their highly social lifestyles – and steal their food, a process known as kleptoparasitism. It might not be a complete loss for the victims, either. Drongo thieves give plenty of alarm calls along the way, and these may help the meerkat and babbler groups avoid predation1.

Perhaps not surprising for an accomplished mimic, the fork-tailed drongo has a diverse alarm call repertoire that includes its own unique warning “chink” as well as the calls of several other bird species. On the savannahs of the Kalahari Desert, birdwatchers noticed that drongos often seem to use these mimicked calls during kleptoparasitism, swooping in to steal food from pied-babblers immediately after sounding a false alarm1. For Tom Flower at the University of Cambridge, this was fascinating anecdotal evidence, so he set out to test whether these alarm calls are used by the drongos in a deceptive way2.

The first thing Flower needed to do was eliminate the possibility that the drongo false alarms are coincidental. If the drongos are truly deceptive, the calls should only occur when the birds are attempting to steal food. Flower also had to establish that the drongos sound the same, regardless of whether they are using their alarm calls in an honest or deceptive context. Finally, he had to show that the meerkats and babblers respond similarly in both cases.

Fork-tailed drongo

Fork-tailed drongo.

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