We had an unusual visitor this weekend – a cocky grey butcherbird, turning up first in the branches of the Japanese maple that reaches up to our back deck, and then hopping boldly onto the balustrade.
Our butcherbird showing off his hooked beak
Butcherbirds are just the kind of generalists – like fellow “corvoids”, magpies and currawongs – that do really well in urban areas. But we’re rarely had them turn up at our place before.
And this lovely lad (or lass – they look too similar for an amateur like me to distinguish) was notable in another way, too – it had only one fully functioning eye.
Looking side on you could see a glimmer of a right eyeball, but it was sunk back into the feathers of the head – on a front view only his inquiring left eye was visible.
Our one-eyed butcherbird
The wounded eye seemed to have healed long ago – this guy was distinctly perky and healthy looking, if a little edgy. And this was an adult bird – no sign of the brown and buff colours of a juvenile (like this one spotted at Narrabeen Lake a few years ago). So whether it had been injured as a chick or as an adult, it seems to have been getting along okay for quite some time.
Juvenile grey butcherbird
In the past, animal rescue organisations assumed that birds with serious injuries to an eye wouldn’t make it if they were released from captivity. Usually birds found wounded in this way were euthanised. But in Germany and the US, researchers and birdwatchers have reported hunting birds like owls and eagles surviving for years in the wild – and even successfully breeding and raising chicks – with only one functional eye.
On a first glance, it seems obvious that binocular vision would be important for judging distances when flying. An early twentieth century ornithologist proposed that “a bird is a wing guided by an eye” but it seems there’s a lot more to eyesight in birds than navigating through the air.
Researchers think that binocular vision is more about being able to see what you’re doing with your beak than getting around on the wing. Birds that have to do tricky things with their bills – cormorants making sure the fins of the fish they’ve just caught are in the right position to slide nicely down their throats, for instance – need to see what they’re doing. Having your eyes at the front of your head means you’re less likely to spot a predator from behind, but it’s worth it for the tucker.
It was interesting to watch our visitor managing life with a limited visual field. He could certainly fly, and RB saw him successfully catch something that was scuttling around on the deck. That said, when we (naughtily) fed him a few pieces of meat, he seemed to struggle a little to get a handle on it.
He was also pretty twitchy, reacting to every sound, looking regularly over his shoulder so he could keep tabs on his surroundings with his good left eye. Butcherbirds usually dive down on prey from above, and as he looked out for tasty treats below, he kept his head cocked to maximise his vision. As a someone with only one “good” ear, I recognise the advantages of that head tilt!
Our one-eyed bird keeping an tabs on surroundings with his one good eye
Our visitor also seemed to understand the possibilities of humans as a resource. At one point he flew right up to where I was sitting by the balustrade, looked me in the face and “spoke” to me in a mildly demanding way familiar to me from my teenaged childen. Later on, I went inside, leaving the sliding door was open, just a bit. The butcherbird hopped up to the door, and after a few moments of hesitation, continued straight through into the house.
Butcherbirds are smart and excellent problem solvers. They’re also creative, as my colleague, the violinist and composer Hollis Taylor found, when she started analysing their marvellous improvisational music making. Was our butcherbird visitor just curious, and yearning to see our interior decor? No matter how clever these guys are, that seems unlikely.
I suspect that this guy was looking for friends. Perhaps some local folks who regularly fed him – maybe in a room with a sliding door, just off a deck? Did his human buddies take care of him after his eye was injured? I don’t know but I can say for sure he expected good things from us, and our kind.
Grey butcherbird expecting good things from humans
References
Brown, Matthews (2016) Clever crows: Investigating behaviour and learning in wild
Torresian crows (Corvus orru) and related Cracticids in a suburban environment, Doctoral thesis, Griffith University.
Hegemann, A, Hegemann, ED, Krone, O. (2007) “Successful rehabilitation and release with subsequently brood of a one-eyed Eagle Owl (Bubo bubo)” Berliner und Münchener tierärztliche Wochenschrift 120(5-6):1
Martin, Graham (2017) “What drives bird vision? Bill control and predator detection overshadow flight” Frontiers in Neuroscience 11
Tyrrell,Luke and Fernandez-Jericic, Esteban (2017) “Avian binocular vision: It’s not just about what birds can see, its also about what they can’t” PLOS One, Mar 29.