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Archive for the ‘birds’ Category

bird smarts and theory of mind

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human brain compared to that of a zebra finch, I think

I like birds a lot – how could you not? I particularly like their brains, which considering their ‘beautiful plumage’, their grace in flight, their songs, their treatment of mates and offspring and their dinosaur history, is quite a big call. Not that I’ve ever seen or examined a bird’s brain, but I’ve seen and heard of  some gobsmacking behaviour from some species, so I thought I might check out what’s known about their grey-white matter.

As with so many research fields, there’s been a surge in research into bird brains, and I’ve not heard the term bird-brain used as an insult in recent times. Still, when we think of bird intelligence, we tend to anthropomorphise, to compare them with us – do they play, do they use language or tools, do they recognise us individually, can they solve the same sorts of problems we can? That’s understandable enough, but in studying bird brains we should be just as thoughtful about the differences as the similarities.

The birds that have stood out for us so far are corvids – ravens, crows, jays and magpies, though many parrots such as the sadly endangered kea of New Zealand have also caught researchers’ attention. So how do these small-brained creatures manage to do the things that so impress us? Well for a start it may be more a matter of numbers than actual size (and it should be noted that birds have the largest brain to body ratio of any creature). Some research published in July 2016, which received a lot of media attention, found that bird brains pack neurons more densely than other animals. It was previously thought that neuron density didn’t vary much between species, but it’s now becoming clear this isn’t so, and actual brain size isn’t such a reliable guide to intelligence. But bird brains are really small compared to those of primates, so there must surely be other differences besides density.

But the 2016 research, which featured a revolutionary method for sampling brain tissue and making neuron counts, found that, in fact, a parrot brain contained as many neurons as some mid-sized primates. However, it’s also true that a bird’s brain is structurally different. Unsurprisingly, in the past, bird brains were thought of as primitive, and were classified as such, probably because they’re far removed from us on the evolutionary bush. Anthropomorphism again – understandably we used to feel that the only really intelligent creatures apart from us were those most closely related to us, but in recent decades we’ve learned that cetaceans, octopuses, elephants and birds, none of which are close to us  evolutionarily, are highly intelligent creatures. And they’re not all mammals, and in the case of the octopus, not even vertebrates. This is quite exciting for our understanding of intelligent life forms – they can have a multitude of ‘brain plans’.

The first important bird brain anatomist was the 19th century German naturalist Ludwig Edinger, whose work was so influential that it provided the orthodox view until a few decades ago. Noting the very different structure of the bird brain, Edinger understandably assumed they couldn’t be as smart as mammals, and being one of the first to name brain structures in birds, he assigned names such as paleostriatum, suggesting a very basic region involving instinctual and motor activity. Basically, he assumed birds lacked a neocortex altogether. However, we now know that the bird brain evolved from the pallium rather than the striatum, and in 2005 it was agreed that an overhaul of bird brain nomenclature was required. All part of our more informed and respectful approach to these wondrous creatures.

National Geographic, in combination with other interested organisations, has declared 2018 the Year of the Bird, and has some fascinating pieces on bird behaviour on its website. That’s where I learned that, according to one researcher, birds’ brains are more distributed ‘like a pizza’, whereas the mammalian brain is more layered. However, the wiring that underlies long-term memory in birds (and they clearly have impressive long-term memory) and decision-making is similar to that in mammals. 

Here are just a few of the extraordinary behaviours discovered. Green-rumped parrotlets of South America use calls as names for their chicks. Male palm cockatoos of New Guinea court females not only with calls but by drumming on hollow trees with twigs and seedpods – arguably a form of music. Goffin’s cockatoos, from Indonesia, make and use tools in captivity even though they’ve never been seen to do so in the wild. They’re also expert at opening locks. The National Geographic video ‘Beak and Brain: genius birds down under’ compares the kea of New Zealand’s South Island to the New Caledonian crow as problems solvers tasked with overcoming a variety of obstacles to obtain their favourite treats. It makes for riveting viewing. Other videos online show crows creating hooks on sticks and using them to pull food out of holes. 

Another video, involving experiments with jackdaws by Princess Auguste of Bavaria (really), a behavioural scientist, shows that these birds are much influenced by the gaze of humans, and can be directed to act simply by the gaze of a human they have bonded with. They also appear to know when they’re not being watched, and can act more boldly in such circumstances. All of this raises obvious questions, voiced by Auguste in the video. How do jackdaws think? How is it similar to the way we think? Do they recognise intentions? Do they have a theory of mind?

This theory of mind issue comes up with a lot of birds, and other animals. It refers to whether and to what extent a creature has the ability to attribute any or all of the variety of possible mental states to itself and/or others. The question of an avian theory of mind was explored in a study entitled ‘ravens attribute visual access to unseen competitors’. In describing their experiment, the authors highlight what they see – or what skeptics see – as a problem with much experimental work that tests for theory of mind in other species. This is the question – as I understand it – of whether the bird or animal actually ‘sees’ or reads what conspecifics are thinking, or is simply following particular observable cues. It was a complex experiment involving caching (hiding a store of food for later consumption, a common raven behaviour), peepholes that were either open or closed, and inference (by the researchers) from observed behaviour to either ‘minimal’ or ‘full-blown’ Theory of Mind. As a dilettante I found much of the discussion and analysis beyond me, but I found these remarks interesting:

In conclusion, the current experiment, together with the other recent studies on chimpanzees11,12, provides strong evidence against the skeptical hypothesis that the social cognition of nonhuman animals is limited to behaviour-reading. Peephole designs can allow researchers to overcome the confound of gaze cues, but further experimental work is needed to determine the specific limits of ravens and other animals—including humans—on such tasks.

In my general reading on these matters I’ve definitely found something like a rift between the skeptics on the behaviour of higher primates, dolphins and other ‘smart’ creatures, and those who have pushed, sometimes naively, other-life smarts with regard to ‘language’, memory and emotional intelligence. What I think needs to be kept clearly in mind is that in examining intelligence, or brain power or whatever, human intelligence may be only one of a possible infinity of gold standards. Is Theory of Mind itself an anthropomorphic concept, or one that lends itself too easily to anthropomorphic thinking? 

Meanwhile, experimentation and investigation of the neurological underpinnings of bird behaviour will continue, and I’ll be watching for the results. Just about to embark on Jim Robbins’ book The wonder of birds, and I hope to learn more especially about bird neurology in the future, and how it relates to birdsong. That’s a whole other issue.

Written by stewart henderson

November 2, 2018 at 9:40 am

some stuff about dinosaurs and their relationship to birds

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Archaeopteryx lithographica with its long bony tail – I took this pic myself at London’s Natural History Museum

Jacinta: Let’s talk about dinosaurs. Are they a thing?

Canto: Of course they are, what are you talking about?

Jacinta: Well I read recently in a New Scientist article that for quite some time in the recent past dinosaur experts didn’t really think ‘dinosaur’ existed as a scientific classification. A new way of classifying was needed because some dinosaurs were bird-hipped and some were lizard-hipped, though they were neither birds nor lizards. So, new names were required.

Canto: Right, so some had hips like lizards, but were clearly not lizards because they had anatomical features that set them apart, and the same went for those that had hips like birds?

Jacinta: Yes I think that’s right. Let’s talk as we learn. Bird-hipped dinos are ornithischians – think ornithology – and the lizardy ones are called saurischians. It was Harry Seeley who shook up the dinosaur-loving world back in 1887 when he argued, before the Royal Society, that what they’d thought were dinosaurs (a term coined by Richard Owen) were really two separate groups, based on those hip bones. Seeley was right about the two groups, but the term ‘dinosaur’, which of course has never disappeared in popular writing, has been rescued over time for science by agreement on other features which bespeak ‘dinosaur’. This has much to do with cladistics, which we may or may not discuss later.

Canto: So the first dinos appeared some 235 mya in the late triassic period, but interestingly they flourished between two major extinction events, the Triassic-Jurassic extinction event about 201 mya, a very sudden event that allowed dinosaurs to fill vacated ecological niches on land, and the Cretaceous-Paleogene (or Cretaceous-Teriary, or K-T) extinction event of 66 mya, which wiped out all the non-avian dinos.

Jacinta: And it should be mentioned that birds are now considered feathered avian dinosaurs, descended from earlier therapods, which strangely are saurischians (lizard-hipped), though a very recent and still controversial paper has reclassified them as ornithischians. I should also mention that dinosaur researchers are a notoriously feisty and bickering tribe, from what I’ve heard.

Canto: I’ve started ploughing through a course on dinosaurs via youtube – The Natural History of Dinosaurs – and I’ve already learned some words, just as background: lithify, diagenesis and coprolite. I’ll let you know if anything exciting crops up, but tell me more about birds being the only remaining dinosaurs and how we know that.

Jacinta: Well, it’s been known since at least the discovery of Archaeopteryx, the type specimen of which was found just two years after Darwin published The Origin of Species, that there are clear anatomical similarities between birds and non-avian dinosaurs. Feathers and hollow bones, for example. There’s also evidence that they share nesting and brooding behaviour. There are also relations with non-avian dinosaurs, some species of which also had feathers, and these discoveries are raising fascinating questions about the origin of flight in these creatures. Of course it’s all very controversial and some researchers are still holding out on the dinosaur-bird link, suggesting other archosaurs were the ancestors.

Canto: What’s an archosaur?

Jacinta: It means ‘ruling reptile’ and these are creatures which first emerged some 300 mya, and they’re the ancestors of living reptiles today. They’re also the ancestors of birds, and dinosaurs. So they’re a larger and older group. Presumably the hold-outs have reason to think birds emerged out of some reptilian line that was distinct from theropod dinosaurs. But that’s nothing to the arguments about the evolutionary steps that led from maniraptoran theropods (perhaps) to modern birds, or the arguments about the origin of flight. Now let me point out that theropods are a suborder of dinosaurs with hollow bones and three-toed limbs, which have long been classed as saurischians until this very recent paper discussed in the New Scientist article, which reclassifies them as ornithiscians. And this seems to be another step – if it holds – towards our understanding of the relationship between birds and their ancestral dinosaurs. An earlier but still pretty recent step were the discoveries, particularly out of China, of a number of fossilised dinosaurs with evidence of feathers, or proto-feathers, and all this, together with advances in analysing and categorising existing specimens using cladistics described in Wikipedia as ‘a method of arranging species based strictly on their evolutionary relationships, using a statistical analysis of their anatomical characteristics’.

Canto: I get very confused about all this. Weren’t there flying dinosaurs – we used to call them pterodactyls – and did they have feathers, or were their means of flight completely different? I seem to remember them depicted like gliders – I mean of the animal kind, with great flaps of skin to catch the wind… Of course that was long before any talk of feathered dinos.

Jacinta: Well hopefully I’ll get to that. Let me talk first about Archaeopteryx, which they reckon dates back to about 150 million years ago. It was probably about the size of a magpie, though there may have been different species of different size (only 11 fossil specimens have been discovered so far). They had feathers, but it’s not known whether they flew like modern birds (flapping flight) or merely glided. A recent study (which I’ve not read) has argued that their flight capabilities were quite limited. They had long, bony tails, which I’m assuming would’ve hampered long-term flight. Interestingly, complex and, for me, impossible-to-verify coloration analyses have presented evidence that the feathers of these critters were a matte black, at least predominantly. Of course it’s hard to prove all this conclusively with 150 million-year-old animals, but speculation and analyses continue, for example on the brain-case of one Archaeopteryx specimen, to determine whether it had a brain for flight (e.g. adequate eyesight, hearing and muscle manipulation). Most of this converges on a limited flight ability, but just how limited will be endlessly argued. And concerning the evolution of birds and flight, there’s a ‘trees-down’ theory (think of sugar gliders etc) and a ‘ground up’ theory. Where does Archaeopteryx fit with those alternatives? That’s still up for grabs.

Canto: Okay, so what about pterodactyls, are they still a thing? Dactyl means digit or finger, doesn’t it?

Jacinta: Winged finger. Yes, they’re a species of pterosaur, with thirty known specimens. They presumably achieved fame among the children of the world as the first-known flying dinosaurs – but they’re not dinosaurs. It’s confusing because ‘saur’ means ‘lizard’, and ‘dinosaur’ means ‘terrible lizard’ and ‘pterosaur’ means ‘winged  lizard’ and they all seem to be connected…

Canto: So what about their relation to birds? Any sign of feathers?

Jacinta: They may have had downy feathers here and there, but not for flight. Their wings were more like those of bats, and they were originally classified as an archaic type of bat. In fact, in the early days of taxonomy, many fossils that had vague similarities to the first pterodactyl fossils discovered in the late 18th century were wrongly designated as pterodactyls, which probably explains their general popularity. It has taken years and many improvements in analysis and dating to sort out the mess, and apparently it still hasn’t been sorted. Anyway, they’re not seen as ancestral to birds. But I may be wrong.

Canto: Wow. Disappointing.

Jacinta: So getting back to the origin of birds, the question of clavicles (collar bones) is important. Birds have wishbones (furculae), which are fused clavicles. The question of bird ancestry has hung on these clavicle bones to a large degree. They’re delicate bones, not easily preserved, and it was long thought that they didn’t exist in dinosaurs. This view has been completely overturned, and in fact most of our understanding about the relationship between birds and earlier dinosaurs come from skeletal studies, or re-examinations, as well as studies of musculature and internal organs, though of course it’s feathers that capture the public’s imagination. But of course there’s a lot of controversy about the how and when of bird evolution, and the evolution of flight, which you’d expect from such scant solid evidence together with intense scientific and public interest.

Canto: Well, I’ve learned something more than the little I knew before about dinosaurs. And their hips. I’ll watch the rest of The Natural History of Dinosaurs’, and we’ll speculate some more in a later post.

Written by stewart henderson

September 4, 2018 at 1:03 pm

does this change everything? Paris, Naomi Klein, extractivism and blockadia

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Canto: Well I’ve just managed to finish reading Naomi Klein’s great big book about the politics of climate change, This changes everything, and since this more or less coincides with the recent political decisions made about tackling climate in Paris, I thought we might spend this session, or even a few sessions, on the future of clean energy, the fossil fuel industry and so forth.

Jacinta: Ah yes, the Paris conference, can you fill me in on that? All I know is that the outcome is being touted as a turning point, a watershed moment, but I presume none of it is enforceable, and I can’t really see the fossil fuel giants giving up the ghost, or considering anything much beyond business as usual…

Canto: Okay, the UN climate change conference in Paris ended on December 12 2015, having run for about 3 weeks. The principal outcome has been the Paris agreement, which was a more substantive agreement on emissions reduction than has been achieved in the past. It apparently represents a consensus drawn from some 196 national representatives.

Jacinta: And I seem to recall the figure of 2% being bandied about. What was that about?

Canto: Ummm, I think you might be referring to the plan, or hope, to limit global warming to 2 degrees, through zero net greenhouse gas emissions in the second half of the 21st century, globally.

Jacinta: Wow, that’s some hope.

Canto: Well the hope is to keep the warming to well under 2 degrees C, preferably aiming for 1.5, which would entail substantial reductions well before 2050, but of course this is all promises, promises.

Jacinta: So what about enforcement, and how is this going to be achieved nation by nation, considering that some nations are huge emitters, and some nations, like India, are still developing and industrialising?

Canto: Right so there are all these semi-commitments and promises, but crunch time starts in April 2016, from which time the relevant parties are asked to sign up to the agreement – that’s 197 parties in all, including all member nations of the UN, the European Union and some not-quite-nations like Palestine and the Cook Islands. They have a year to sign up, and the agreement will only come into force if 55 countries that produce 55% of global greenhouse emissions sign up.

Jacinta: Wait, does that mean all of the top 55 greenhouse gas emitters, or any 55 that together emit 55% of the greenhouse gases emitted by humans?

Canto: Uhhh, I’m not sure but I think it’s the latter.

Jacinta: Great, so Australia doesn’t have to sign. Quel soulagement!

Canto: Funny that, because the Wikipedia article on the Paris agreement, specifically mentions the climate change ‘skepticism’ of our conservative government…

Jacinta: Wow, what an honour.

Canto: Time to lobby our environment minister. Of course there are a lot of people protesting that this agreement doesn’t go far enough – not so much in the targets as in the voluntary nature of it all. I mean, it may not even come into voluntary force if nations don’t sign up to it, and of course there’s no enforcement mechanism. Here’s how Wikipedia describes the situation:

The Agreement will not become binding on its member states until 55 parties who produce over 55% of the world’s greenhouse gas have ratified the Agreement. There is doubt whether some countries will agree to do so. Each country that ratifies the agreement will be required to set a target for emission reduction, but the amount will be voluntary. There will be [no] mechanism to force a country to set a target by a specific date and no enforcement if a set target is not met. There will be only a “name and shame” system or as Janos Pasztor, the U.N. assistant secretary-general on climate change, told CBS News (US), a “name and encourage” plan.

Jacinta: Well I think it’s definitely a positive development, which will add pressure to the fossil fuel industries and their supporters. I notice that one of our green pollies was castigating the government the other day about the expansion of the Abbott Point coal terminal, citing the Paris agreement. That’s going to be a much repeated dagger-thrust into the future. So how does this all connect with Naomi Klein’s book?

Canto: Well I think you’re right to accentuate the positives. I mean, how can you seriously police or enforce such an agreement without interfering with the ‘national sovereignty’ that so many nations bellow about – especially when there’s a hint of criticism from the UN? So the first real positive coming from this confab is that all the parties are in agreement about the imminent threat of AGW, and they’ve actually managed to come to a broad agreement over a target and a goal. That’s a big deal. The second positive is, as you say, the impact of that consensus on the battle against the cashed-up fossil fuel industries, and the mostly conservative governments around the world that are still into science denialism, including our own government. As to This changes everything, Klein sees the AGW issue as a possible game-changer for the politics of global capitalism and free marketeering, which is rather ambitious, but she puts her faith in the protest movements, the indigenous rights movements and other grassroots movements who are, as she sees it, rising up more than ever before to create headaches for the business-as-usual model. She calls this grassroots approach ‘blockadia’, probably not an original coinage.

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Jacinta: So she sees it as an issue to fight global capitalism, to replace it with… what? Surely the renewable energy industries are capitalist industries too?

Cant: Well yes, I think there’s a certain amount of idealism in her view, an old-fashioned back-to-nature ethic, and I don’t think she emphasises the solutions and the science as much as she emphasises the problems and the politics, but if you take the view that the fossil fuel industries need to be phased out, sooner rather than later, you’ll perhaps be as much inspired by the heroic and hard-working efforts to prevent mining and drilling – which, let’s face it, have caused huge devastation in many areas – as you will by the innovations and improvements in clean energy. Which brings me to the other term used a lot in Klein’s book – extractivism.

Jacinta: Which presumably stands not just for the fossil fuel industry but the whole mentality of ‘what can we extract from this entity?’, be it animal vegetable or mineral.

Canto: The ancient Greeks did it with their slaves, the British did it with their colonies…

Jacinta: And their slaves..

Canto: The tobacco industry are doing it with the resource of willing smokers in non-western countries, poachers are doing it with elephants in Africa, the porn industry is doing it with pretty and mostly impoverished girls in the US and Europe, multinational companies are doing it with cheap labour worldwide. Extractivism has always been with us…

Jacinta: Point taken but I think we’re getting a bit carried away here. I presume Klein was using the term in a more limited sense, though perhaps with a nod to broader extractivist tendencies. And I have to say, quite apart from the devastation caused by tailings and disasters like Deepwater Horizon, I’ve always felt there’s something not quite right about our recent cavalier exploitation of a process of incredibly slow transformation of once-living and evolving entities – our ancestors in a sense – into coal and oil. Doesn’t it seem somehow sacrilegious?

Canto: Well perhaps, but I’m not sure if ‘exploitation’ is the right word. People get exploited. Okay animals can get exploited. But dead matter turning into coal? All species do what they can to survive and thrive, and they don’t worry about the cost to others or to historical processes. Right now parrots are feasting on my neighbour’s fruit trees. They’re extracting what they can in one go, and they’ll be back for more unless someone stops them. My neighbours might consider the parrots a pest, but that’s only because they want to extract as much as they can from those trees, to make jam, or to add fibre and other nutritional elements to their diet. As to the fossil fuels I’m all for keeping them in the ground, but more because of the damage they do to our atmosphere than because it’s ‘nice’ and ‘respectful’ not to extract them.

Jacinta: Spoken like a true instrumental scientist, but I can’t help feeling there’s more to it than you say. But what do you think about the view that this is a game-changer for global politics? Klein subtitles her book ‘capitalism v the climate’, as if one or the other has to come out on top. Do you think that’s really the choice?

Canto: No I don’t, but I doubt that Klein really imagines, or even wants this to spell the end of capitalism. I’m no anti-capitalist of course, but then I see capitalism in much broader terms. Those parrots are capitalising on a resource previously unavailable to them, and they’ll continue to do so unless prevented, by netting or something worse. Fossil fuel companies have learned to capitalise on a resource previously unavailable to them, before we learned how to process and extract energy from such material, and they’ll continue to do so unless they’re prevented, by legislation, by blockadia, or by the availability of more attractive alternatives, such as the more effective exploitation of the sun. Or capitalising on the solar resource.

Jacinta: So you believe that all humans, or rather, all creatures are capitalists? Isn’t that a bit of a narrow view?

the capitalist menace

                                                                                  the capitalist menace

Canto: Well no, as I say, I think it’s a broad view of the capitalist concept. But of course you might say that this hardly accounts for blockadia. If we’re all capitalists at heart, how do we account for the amount of energy so many citizens put into blocking capitalist exploitation? But that’s easily explained by the parrots and fruit example. The parrots’ gain is the neighbours’ loss. The neighbours have gone to a lot of trouble cultivating the ground, planting the trees, watering and fertilising, and these pesky parrots have come along without so much as a by your leave, and devastated the crop. Similarly farmers who have put a lot of time and energy into cultivating their land, and indigenous people who have learned over generations how to fish and hunt in an area in such a way that stocks can still be replenished rather than devastated, are naturally outraged that these fossil fuel companies have come along and ‘poisoned the well’. The farmers and the indigenes are also capitalists, very effective capitalists for their own needs, but they’re faced with different types of capitalists with different needs. So, to me, it’s a matter of resources, needs, diversity and negotiation.

Jacinta: Hmmm, well I’m inclined to agree with you. Of course indigenous people, such as our Aborigines, like to talk of spiritual connections to the land and its bird and animal life, but I’m not much into spirituality. But I like the idea that even though they’re into hunting and killing those creatures in order to survive, they tell stories about them, and exhibit a great deal of respect and fondness for them. That seems healthy to me.

Canto: I agree completely. I’m not trying to say ‘all is capitalism’. There’s much more to life than that. The beauty of that story-telling and that affection for the land and its inhabitants and their ways is that it’s not a kind of master-race view. The Judeo-Christian view has been that all things, including all creatures, have been put here for our benefit. Of course modern Christianity has largely re-interpreted this as custodianship, which is an improvement, but I prefer the perspective that we’re all in this together, and we should look out for each other. Birds have to eat, and they like to eat fruit, and birds are fantastic creatures. They deserve our consideration.

Jacinta: Well that’s a nice note to end on. And what about the fossil fuel industry?

Canto: I think it’s had its day. It’s time to move beyond it.

Written by stewart henderson

December 31, 2015 at 8:45 am

this one’s for the birds

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clevercrow1

Canto: If anybody doesn’t appreciate the beauty and complexity and general magnificence of birds they should pee off and never darken this blog again.

Jacinta: Right. Now what brought that on, mate?

Canto: Oh just a general statement of position vis-à-vis other species. Charles Darwin, an old friend of mine, was pretty disdainful of human specialness in his correspondence, but he kept a low profile – on this and everything else – in public. I want to be a bit more overt about these things. And one of the things that really amazes me about birds, apart from their physical beauty, is how much goes on in those teeny noggins of theirs.

Jacinta: Yes, but what really brought this on? I haven’t heard you rhapsodising about birds before.

Canto: You haven’t been inside my vast noggin mate. Actually I’ve been taking photos – or trying to – of the bird life around here; magpies, magpie-larks, crows, rainbow lorikeets, honeyeaters, galahs, corellas, sulphur-crested cockies, as well as the pelicans, black swans, cormorants, moorhens, coots and mallard ducks by the river, not to mention the ubiquitous Australian white ibis and the masked lapwing.

Jacinta: Well I didn’t know you cared. Of course I agree with you on the beauty of these beasties. Better than any tattoo I’ve seen. So you’re becoming a twitcher?

Canto: I wouldn’t go that far, but I’ve been nurturing my fledgling interest with a book on the sensory world of birds, called, appropriately, Bird sense, by a British biologist and bird specialist, Tim Birkhead. It’s divided into sections on the senses of birds – a very diverse set of creatures, it needs to be said. So we have vision, hearing, smell, taste, touch, and that wonderful magnetic sense that so much has been made of recently.

Jacinta: So we can’t generalise about birds, but I know at least some of them have great eyesight, as in ‘eyes like an eagle’.

Canto: Well, as it happens, our own Aussie wedge-tailed eagle has the most acute sense of vision of any creature so far recorded.

Jacinta: Well actually it isn’t ours, it just happens to inhabit the same land-form as us.

Canto: How pedantic, but how true. But Birkhead points out that there are horses for courses. Different birds have vision adapted for particular lifestyles. The wedge-tail’s eyes are perfectly adapted to the clear blue skies and bright light of our hinterland, but think of owl eyes. Notice how they both face forward? They’re mostly nocturnal and so they need good night vision. They’ve done light-detection experiments with tawny owls, which show that on the whole they could detect lower light levels than humans. They also have much larger eyes, compared with other birds. In fact their eyes are much the same size as ours, but with larger pupils, letting in more light. They’ve worked out, I don’t know how, that the image on an owl’s retina is about twice as bright as on the average human’s.

Jacinta: So their light-sensitivity is excellent, but visual acuity – not half so good as the wedge-tailed eagle’s?

wedge-tailed eagle - world's acutest eyes

wedge-tailed eagle – world’s acutest eyes

Canto: Right – natural selection is about adaptation to particular survival strategies within particular environments, and visual acuity isn’t so useful in the dark, when there’s only so much light around, and that’s why barn owls, who have about 100 times the light-sensitivity of pigeons, also happen to have very good hearing – handy for hunting in the dark, as there’s only so much you can see on a moonless night, no matter how sensitive your eyes are. They also learn to become familiar with obstacles by keeping to the same territory throughout their lives.

face of a barn owl - 'one cannot help thinking of a sound-collecting device, quoth researcher Masakazu Konishi

face of a barn owl – ‘one cannot help thinking of a sound-collecting device’, quoth researcher Masakazu Konishi

Jacinta: So they don’t echo-locate, do they?

Canto: No, though researchers now know of a number of species, such as oilbirds, that do. Barn owls, though, have asymmetrical ear-holes, one being higher in the head than the other, which helps them to pinpoint sound. It was once thought that they had infra-red vision, because of their ability to catch mice in apparently total darkness, but subsequent experiments have shown that it’s all about their hearing, in combination with vision.

Jacinta: Well you were talking about those amazing little brains of birds in general, and I must say I’ve heard some tales about their smarts, including how crows use cars to crack nuts for them, which must be true because it was in a David Attenborough program.

Canto: Yes, and they know how to drop their nuts near pedestrian crossings and traffic lights, so they can retrieve their crushed nuts safely. The genus Corvus, including ravens, crows and rooks, has been a fun target for investigation, and there’s plenty of material about their impressive abilities online.

seeing is believing

seeing is believing

Jacinta: So what other tales do you have to tell, and can you shed any light on how all this cleverness comes in such small packages?

Canto: Well Birkhead has been studying guillemots for years. These are seabirds that congregate on cliff faces in the islands around Britain, and throughout northern Europe and Canada. They’re highly monogamous, and get very attached to each other, and thereby hangs another fascinating tale. They migrate south in the winter, and often get separated for lengthy periods, and it’s been noted that when they spot their partner returning, as a speck in the distance, they get highly excited and agitated, and the greeting ceremony when they get together is a joy to behold, apparently – though probably not as spectacular as that of gannets. Here’s the question, though – how the hell can they recognise their partner in the distance? Common guillemots breed in colonies, butt-to-butt, and certainly to us one guillemot looks pretty well identical to another. No creature could possibly have such acute vision, surely?

Jacinta: Is that a rhetorical question?

Canto: No no, but it has no answer, so far. It’s a mystery. It’s unlikely to be sight, or hearing, or smell, so what is it?

Jacinta: What about this magnetic sense? But that’s only about orientation for long flights, isn’t it?

Canto: Yes we might discuss that later, but though it’s obvious that birds are tuned into their own species much more than we are, the means by which they recognise individuals are unknown, though someone’s bound to devise an ingenious experiment that’ll further our knowledge.

Jacinta: Oh right, so something’s bound to turn up? Actually I wonder if the fact that people used to say that all Chinese look the same, which sounds absurd today, might one day be the case with birds – we’ll look back and think, how could we possibly have been so blind as to think all seagulls looked the same?

Canto: Hmmm, I think that would take a lot of evolving. Anyway, birds are not just monogamous (and anyway some species are way more monogamous than others, and they all like to have a bit on the side now and then) but they do, some of them, have distinctly sociable behaviours. Ever heard of allopreening?

Jacinta: No but I’ve heard the saying ‘birds of a feather flock together’ and that’s pretty sociable. Safety in numbers I suppose. But go on, enlighten me.

Canto: Well, allopreening just means mutual preening, and it usually occurs between mates – and I don’t mean in the Australian sense – but it’s also used for more general bonding within larger groups.

Jacinta: Like, checking each other out for fleas and such, like chimps?

Cant: Yeah, though this particular term is usually reserved for birds. Obviously it serves a hygienic purpose, but it also helps calm ruffled feathers when flocks of colonies live beak by jowl. And if you ever get close enough to see this, you’ll notice the preened bird goes all relaxed and has this eyes half-closed, blissed-out look on her face, but we can’t really say that coz it’s anthropomorphising, and who knows if they can experience real pleasure?

Jacinta: Yes, I very much doubt it – they can only experience fake pleasure, surely.

Canto: It’s only anecdotal evidence I suppose, but that ‘look’ of contentment when birds are snuggling together, the drooping air some adopt when they’ve lost a partner, as well as ‘bystander affiliation’, seen in members of the Corvus genus, all of these are highly suggestive of strong emotion.

Jacinta: Fuck it, let’s stop beating about the bush, of course they have emotions, it’s only human vested interest that says no, isn’t it? I mean it’s a lot easier to keep birds in tiny little cages for our convenience, and to burn their beaks off when they get stressed and aggressive with each other, than to admit they have feelings just a bit like our own, right? That might mean going to the awful effort of treating them with dignity.

Canto: Yyesss. Well on that note, we might make like the birds and flock off…

how the flock do they do that?

how the flock do they do that?

Written by stewart henderson

November 13, 2015 at 12:06 pm