Dear Readers, I was taking a walk in St Pancras and Islington Cemetery with my friend A on Monday when we spotted this juvenile green woodpecker, sitting very happily on top of a gravestone. What handsome birds they are, although this one doesn’t have the red cap of an adult. You can clearly see the stiff tail feathers that help the bird to stay upright when working their way up a tree trunk, although the favoured food of green woodpeckers is ants, lots of them.
As we watched, we noticed that the woodpecker and their parent seemed to be being followed by several nosy magpies. The adult woodpecker flew down and started hammering relentlessly into an area of raised, dry ground next to one of the graves, which probably held an ants’ nest. After a few minutes the magpie seemed to approach aggressively and the woodpecker flew off, leaving the magpie to appear to hoover up whatever the woodpecker had unearthed.
I am not in the least surprised that the magpie was intelligent enough to benefit from another bird’s hard work – the crow family has a history of this, with ravens in the Northern Woods of Scandinavia leading wolves and bears to carcasses that they can’t open up themselves. This was the first time I’d seen magpies and woodpeckers interacting though, so do let me know if you’ve ever seen anything similar. I suspect that the web of life is far more intricate and nuanced than we can ever imagine.
Now, how about that headline? For years I have been promulgating the long-held belief that the reason that woodpeckers don’t give themselves concussion with all that hammering is because they have shock absorbers in their heads. Much like the little unicorn horn on the back of Dürer’s rhinoceros (which doesn’t exist, but was replicated by everyone who ever painted or drew a rhino for years afterwards) we have all been blithely repeating the woodpecker story.
It is true that woodpeckers have spongy bone between their beaks and their brains, but instead of absorbing the shock from the blows, scientist Sam van Wassenburgh at the University of Antwerp has found that that the spongy bone is only there to reduce weight, essential for a flying animal. Videos of three species of woodpecker hammering on wood showed that the spongy bone didn’t have any effect on cushioning the blows – slowing down the video showed that the birds’ heads and eyes stopped moving at the same time as their beaks did. Van Wassenburgh concluded that the bird’s brains are so small and light, and so cushioned by the naturally-occurring fluid in their skulls, that they would have to hammer twice as fast, or hit surfaces four times as hard, in order to suffer concussion.
And so, another idea bites the dust, but this is what science is all about – a scientific theory is the best model that we currently have for why something happens, until someone does the research and it’s replaced by a theory that fits what happens better. I love that we are always learning, and always moving the consensus on. I think two years of studying science has made me more eager to look for evidence, and to not take things at face value, especially in a time of so much deliberate misinformation. We live in exciting times, but we have to be careful about where we get our information from.
You can read the whole woodpecker article, and watch the woodpeckers getting stuck in with their hammering, here.