Jeez, chickens go to bed early. I’m outside getting the washing, and ok, it’s heading towards dusk, but not only can I see the location of my smalls, visibility’s so good I can even spot and dodge the brush turkey doings as I go. But the chooks are already tucked up in their palatial quarters, or in the case of Snowball (pictured above), having a nap in an elevated position while waiting to be eaten.
So, twilight is more complicated than you might think, and I’m not talking about the teen vampire series. Apparently it comes in three types. As the sun first sinks, there’s civil twilight. Technically, that’s when the centre of the sun is 6 degrees below the horizon – in good weather you can still see the things around you (say, your knickers on the line, or an inconvenient pile of guano). Then, after about 20 minutes, more (as you get closer to the poles) or less (closer to the equator), you have nautical twilight. The sun is 12 degrees below the horizon now, and if you’re a sailor, you can take a bearing on the stars with the horizon still visible. If you forgot to pick sweet potato greens before sundown, you’re rummaging around in the cupboard for a torch.
After nautical twilight comes astronomical twilight, with the sun 18 degrees below the horizon. To an untutored eye it might appear as if night has finally arrived, but impatient astronomers wanting to check out nebulae will be still pacing up and down waiting for full dark. Of course, you won’t get the full sequence come the summer in Trondheim (civil twilight from sunset to sunrise), Glasgow (nautical twilight for most of the darker hours) or even London (astronomical twilight all night long, even without throwing in the orange glow of light pollution).
I find this orderly taxonomy of darkening moments curiously soothing, an effect only slightly diminished on reading that nerdy acronyms like EENT (end evening nautical twilight) aren’t just used by meteorologists and astronomers to document the passing days and track the movements of the stars, but also in military campaigns to synchronise watches.
But all this is from a human point of view. For chickens, it’s different.
If possums have got pretty dud typical mammalian dichromate vision, chickens are rocking their cones. Not just three sets of cones like us, but five, including one that enables them to see ultraviolet light and a double cone for detecting motion. And “cellular sunglasses”: an oil-drop to filter particular wavelengths of light.
But wait! There’s more! Chickens also have, in essence, a third eye. Okay, not as visible as parietal eyes of Tuataras and other less famous reptiles (and related organs in the eyes of other tetrapods – like the receptor that looks like a little blue pimple between this critter’s eyes).
But still, a pineal gland perched up just under skull that receives enough light to regulate sleep and trigger annual reproductive cycles. Extremely cool. Perhaps too cool for some. While researching this post, I noticed, right underneath a webpage spelling out the multidimensional excellence of chicken vision, an advertisement for eye surgery.”Replace tired and baggy eyes with a younger look!”. Presumably the reader, ruminating dolefully on the superiority of the avian retina and the failings of human sight, is primed for this kind of thing.
But perhaps we humans shouldn’t be so grim about our drab colour vision, our tediously symmetrical pair of eyes. At the very least the time our mammalian ancestors spent cowering in a burrow while the dinosaurs strode the earth gave us respectable night vision. We can revel in our fine array of twilights while the shutters come down with a clang at the end of the day for our long time companions.
Okay, The Twilight of the Chickens may not have the apocalyptic ending of the Ragnarøkkr, the Twilight of the Gods. The rivalry between Treasure and Shyla over who gets the highest perch in the upcycled coop doesn’t have the same Wagnerian grandeur as Odin’s battle to the death with the wolf Fenrir. But pleasingly, even the Norse myths have a place for chooks: the end of days is heralded by the crowing of a crimson rooster, a golden rooster, and a rust red rooster. I must tell Andy Ninja.