I’ve just finished Richard Dawkins’s self-narrated audiobook of An Appetite for Wonder: The Making of a Scientist, where, introducing a task given to him by his research supervisor Niko Tinbergen, related to nature versus nurture aspects of animal behaviour, he makes special mention of the White-crowned Sparrow (Zonotrichia leucophrys nuttalli). As it happens, earlier this year I caught this native of North America pecking at a fig.
Is behaviour built in at birth – innate and instinctive? Or is it learned from experience? One way ethologists, who study animal behaviour, try to answer such questions is to compare the behaviour of subjects artificially deprived of normal early life learning opportunities with those raised in their natural habitat.
In the case of birdsong, tests on Sedge Warblers show they automatically know their song without ever hearing the tune from another bird. As Dawkins puts it, they ‘fumble’ towards the final song, trying different sounds and sequences from which they assemble a correct version; so the process is innate: it’s all ‘nature’.
The White-crowned Sparrow also teaches itself to sing its unique song by fumbling and picking out the good bits, but, unlike the Sedge Warbler, it needs to have heard its song from another White-crowned sparrow in early life; it needs a prompt to know where it’s going – so to speak. As for many animal behaviours, including human behaviours, the White-crowned Sparrow’s song is the product of a nature-nurture combo of innate and learned influences. Dawkins wonders what similar early life deprivation experiments, within ethical bounds, might be made to study the human condition.
You can hear the White-crowned sparrows song here at the Cornell Lab of Ornithology.
Quite a cold afternoon’s walk today; but the sun was up, the golfers were out, and so too were our local herons. I snapped this one just before sunset. He’s a Grey Heron (Aredea cinerea) and common in the UK. (I keep an eye out for the Blue Heron and super-rare Purple Heron, that occasionally visit the UK, but have seen neither.)
Herons nest in colonies, and this one looked like it contained three birds: two adults flying back and forth to the nest, and a smaller ‘second winter’ juvenile that stayed put (the one on the left of the pair in these shots).
I was surprised to see nest-building this time of year, but the hardy heron’s extended breeding season sees them happily dropping eggs in late February. That’s not to say the smaller bird here is a chick – they leave the nest by 10 weeks, and this one’s plumage is too mature. I’m guessing it just wasn’t his/her shift for twig collection.
They’re fantastic birds to watch. Very noisy and, to my eyes, especially dinosaury. I also like the retracted neck position adopted for steady flight; it’s like their head goes along for the ride in upper-deck business class. It’s also one way to tell herons apart from cranes.
The Heron’s nest is a large flat platform of twigs in the top of a tree. The males do most of the collecting, the females most of the building.
These last two shots of the nest show an adult bird on the right, and what I suspect is a ‘second winter’ juvenile on the left (tell me if you think differently). Despite the stance, there was no feeding going on here.
It’s days like this that justify carrying heavy cameras and lenses around on the off-chance something might show up. Next phase is to return with the tripod and get some HD movies of these guys. Watch this space!
Tonight I joined the 2011 Darwin Lecture, with Sir David Attenborough speaking on ‘Alfred Russel Wallace and the Birds of Paradise’, organised and hosted by the Royal Society of Medicine in association with the Linnean Society of London.
Fresh back from a trip to Borneo – no less, the spritely 85-year-old was introduced by Professor Parveen Kumar, President of the Royal Society of Medicine, and Dr Vaughan Southgate, President of the Linnean Society.
Be it via the TV or lecture theatre, David Attenborough plays to full houses all the time, and this November evening was no exception.
His account of Wallace’s ocean voyage to the Malay Archipelago and pioneering observations of that unique group of theatrical show-offs: the Birds-of-paradise, made for an informative and fun evening – all the merrier thanks to a generous ration of film clips showing the birds’ unlikely courtship rituals.
But the real take-home for me was Attenborough’s poignant re-telling of the Wallace-Darwin story: How the two independently arrived at that world-changing idea for the origin of species – natural selection – whereby only the better-adapted offspring of animals survive and pass on their qualities to a new generation.
Darwin had for years been working on his own version of natural selection from the comfortable surroundings of his home Down House, but had held back from publishing.
Then in 1858, Darwin receives a letter from Wallace, incapacitated with Malaria and holed-up in a shack on the Mollucas Islands of the Malay Archipelago. In it, he asks Darwin for an opinion on some ideas he’s had on the introduction of new species: ideas very similar to Darwin’s own.
Wallace’s communication is a bombshell. Yet for Darwin, the fear Wallace might publish first, pipping him at the post, is nothing compared to his horror of being branded a thief. So, after consultation with his scientific confidants, including Joseph Hooker but necessarily excluding the remote Wallace – Darwin’s camp decide a joint announcement of their common idea should be made at the Linnean Society in London, in the form of two short essays comprising Wallace’s note and a summary of Darwin’s work.
All goes to plan at the Linnean, and in due course Darwin publishes the full text of the ‘Origin of Species’ – with all the turbulent aftermath that comes with it. Wallace is comfortable with events, and pleased by the new associations he sees himself making in Darwin’s circle. He remains abroad, observing his beloved Birds-of-paradise .
Darwin, Attenborough said, made known his view that Wallace was capable – had he enjoyed Darwin’s own means – of producing the ‘Origin’ himself. Wallace on the other hand was more than grateful that the painstaking task of collation, supporting work, and documentation demanded of the masterwork had fallen to Darwin. In the lingo of the day, they’d reached a gentlemanly solution with no ill feelings all round.
Wallace produced much original work based on his observations of bird populations in the Malay Archipelago, which he captured in his book of the same name (The Malay Archipelago). Specifically, he identified the so-called ‘Wallace-Line‘ that runs between the islands of Bali and Lombok, separating two geographic regions whose animals Wallace found to be distinct and associated with either Australian or Asian origins. What he’d observed, without recognising it as such, was a product of moving land masses – or plate tectonics.
David Attenborough talks about his fascination with birds of paradise (Nature Video)
When I lived in the Midlands of the UK, away from the bussle of London’s controlled airspace, one of my pleasures on an evening was to hire a light aircraft at my local airfield and tootle off for an hour or so practicing maneoveurs and generally enjoying the sunset – all very peaceful.
Except, one evening when I was out tootling above the Cotswolds; like a flash, an RAF Tornado jet whooshed from under me, matching my track but far exceeding my speed, and all uncomfortably close – a disappearing dot before I could blink.
In fact, he was probably a good 500 ft below me and certainly had on-board radar – so nothing actually dangerous going on. (There’s a popular myth – that may be true – that on such occasions the military use light aircraft for practice interception.)
Anyhow, it made an impression on me, and today the memory returned unbidden with these two photographs snapped at the Rick Pond in Hampton Court Park. They show a Sand Martin in a low-level, high speed pass over a convoy of ducklings – as bemused, no doubt, as I was 4000 feet above the Cotswolds (Figs 1 & 2).
I’d been trying to catch the Martins’ aerobatic fly-catching with no success, and started snapping the ducks more as a gesture of resigned failure. I only spotted the Martin when I downloaded the flash card.
This type of ‘buzzing’ seems to be in the Sand Martin’s nature. People on the bank get similar treatment – the bird coming from behind, passing within inches of heads, as if honing their own targeting systems.
I’d left the camera in rapid fire mode of 8 fps, so the time interval between the two photographs is known. If we also know the length of a duck, we can calculate the Martin’s speed, in ducks per second – or more tedious conventional units. So:
Assuming SML = 0.3m (Standard Mallard Length)
Time between pictures at 8 f.p.s = 0.125 s
Ducks passed between frames = 5.75 (use the grid to measure; one duck = 2 grid squares)
Meet the new arrivals. At a pool close to where I live in the south of England, I’ve been following the progress of these cygnets since their birth five weeks ago; the picture and the video were taken about a week after hatching.
The same breeding pair has built a nest in the same spot for the last four years: sometimes they get lucky – othertimes it looks like they go through the motions – or maybe the youngsters get dispatched by predators before I see them.
And for sure, it’s not all sweetness and light. Since I shot the video, one of the cygnets has developed a problem with its neck.
Swans , and particularly cygnets in their first year, are vulnerable to a host of threats: from natural predators like herons, crows, magpies and foxes;
When I visited the brood on 30th May, when the cygnets were about three weeks old, I noticed one of their number struggling to keep its head up. That might be caused by an injury, but it’s also a known symptom of lead poisoning.
As Doreen Graham of the Scottish Society for the Protection of Animals said in this 2007 BBC report : “Lead poisoning is quite easy to identify in a swan because they cannot lift their heads and their heads are resting on their backs”. There was a particularly bad spate of lead poisoning during the 1960s, although since then, with a ban on lead fishing weights, or sinkers, the Royal Society for the Protection of Birds (RSPB) believes the problem has diminished.
Lead shotgun pellets are the other likely culprit. There are bans or restrictions on the use of lead shot throughout the UK, with detail variations across the devolved constituencies; but there’s always the danger of legacy poisoning from old pellets lying in the reeds or on the pool bed.
All swans rest their heads and necks at times – it’s how they rest and sleep; but this one’s doing it most of the time, standing out from the group:
The other cygnets appear to sense the difference, taking the occasional peck at their handicapped sibling:
While the parents appear indifferent:
Fast forward to 8th June, when the cygnets are a month old, and at first sight there’s an improvement: it’s all heads-up in this convoy. But on closer inspection, number 4 from the left isn’t quite right:
and in this pre-roost preening session, there’s clearly still a problem:
As twilight deepens, the female swan, or pen, climbs into the nest, followed by the cygnets:
It’s easy to make up stories, but here a parent appears to attend the neck of one of the cygnets (I can’t confirm it’s ‘the’ cygnet):
And they settle for the night:
For now, the afflicted cygnet appears to be growing at a normal rate and, despite some earlier sniping by siblings, appears to be accepted by the group. I’ll be keeping an eye on this family over the coming weeks and update the blog with any developments.
UPDATE 8 July
Happy ending. Here’s the whole crew on 19th June – 11 days after the pics above. All six cygnets holding their heads up high. I’ve only just got round to updating, but if they’ve got this far they’re probably going to make the distance. Whatever was wrong with the afflicted cygnet seems to have worked itself through/out. (Not that these guys aren’t still in a warzone.)
Through a combination of photography and a creeping fascination with avian behaviour and taxonomy (thanks to my wife giving me Colin Tudge’s The Secret Life of Birds for my birthday) I think I’m turning into some sort of accidental ornithologist. Point being, you can expect the occasional photo-flavoured birdy post; and today – it’s woodpeckers!
The female Eurasian Green Woodpecker (Picus viridis) above is one of the three most common woodpeckers found in the UK.
Photographically, woodpeckers are a challenge. The whole family is jumpy, taking off as a matter of principle at the sniff of a threat. So, considering I was sneaking up with no hide, I’m pleased how these turned out. Here are a few more of the male/female pair and a juvenile. You can tell the male by the red flash under his eye (click thumbnail to open slideshow):
And this male Great Spotted Woodpecker (Dendrocopos major)was snapped only a few days ago (click thumbnail to open slideshow):
Globally, there are 218 species4 in the Picidae family to which woodpeckers belong, living in every country with trees except for Australia and New Zealand.
Here are two more I snapped in California. The first set shows an Acorn Woodpecker Melanenpes formicivorus and the Ladder-backed Woodpecker Picoides scalaris (click thumbnail to open slideshow):
Here’s a video of a female Ladder-back hunting for bugs:
Acorn Woodpeckers are expert at turning trees into communal larders or caches. Pecking thousands of small pits in a single tree, they’ll place an acorn in each one – ready for harder times.
This set, again taken in California, is of a female Williamson’s Sapsucker – a member of the family specialising in eating the sap out of small wells drilled into the bark of pine trees:
Woodpeckers are a wonderful showcase for evolutionary adaptation.
Sharp claws set on toes laid out in the zygodactylous pattern – two toes facing forward, two back – are ideal for tree climbing. (Parrots and cuckoos are set up similarly, and elsewhere in the animal kingdom – Chameleons.)
Then there’s the way they hold themselves on the tree trunk.
Like rock climbers and photographers favour three points of contact for security and stability, woodpeckers have evolved a stiff tail to brace against the tree trunk and make a sturdy triangle with their splayed legs. The Sapsucker below demonstrates nicely; you can see her two tail quills bending under the pressure.
Having formed this miniaturised drilling platform, woodpeckers set-to doing their thing, which for a Ladder-backed woodpecker is banging its beak into bark and wood at up to 28 times a second, repeating the act several hundred times a day1.
The aim is to locate and consume insects and sap from under tree bark, a task for which their long, barbed tongue is well suited. But as this Great Spotted demonstrates, the birds are not above pecking the ground if there are bugs and termites to be had.
As hole-dwellers, woodpeckers also peck to hollow out a nest – a process that can take up to a month and involve the removal of tens of thousands of wood chips4.
For me, the woodpeckers’ most impressive adaptation is the multi-element shock absorber system that’s developed in and around its skull to prevent brain damage from all that bashing.
The full complexity of the system has only recently come to light. X-rays of a woodpecker’s head showed that the massive deceleration occuring at beak strike is cushioned and spread out thanks to elasticity in the beak, a spongy area of bone at the front of the skull, and a further special structure – the Hyoid – that directs pressure from the rear of the birds tongue around the back of its head1.
Well that’s a wrap on woodpeckers for the moment. Next phase is to try and catch these guys on HD video; they’re doing some great little courting dances this time of year. Reaches for camouflage gear….
References and further reading
1) A mechanical analysis of woodpecker drumming and its application to shock-absorbing systems. Sang-Hee Yoon and Sungmin Park 2011 Bioinspir. Biomim.6 016003 IOP Publishing doi: 10.1088/1748-3182/6/1/016003