Owls are my favourite birds. I’m sure it has a lot to do with the characters that represented them in books I read when I was young, but years later they continue to excite me whenever I encounter them out in the bush.
Out of all the species that occur in Southern Africa, only the Cape Eagle Owl has never been recorded at Londolozi, so we’re fairly lucky with the owls we see (apart from the pair of barn owls that have taken up residence in a tree near my house; they haven’t let us sleep for over a month now with their all-night shrieking!).
Being almost exclusively nocturnal as a group, owls have clearly had to adapt to be able to hunt their prey effectively in the dark, and while they are famous for their night-vision, this isn’t even what makes them such deadly predators. Well it is in part, but it’s more a combination of factors.
Firstly, they can glide in towards their prey in almost complete silence. Specialised flight feathers alter the air currents flowing over their wings, resulting in a tremendous reduction in noise as the upper- and lower currents merge at the wings’ trailing edges.
Flying in silence, as well as giving no warning to their prey of their approach, also allows the owl to hear a lot better, and this is apparently how they really lock in on their prey. Owls’ ear cavities are offset on the side of their skulls – unlike ours which are symmetrically placed – allowing for a more accurate assessment of where the noise of their prey is coming from, and they can supposedly hunt almost exclusively by sound.
How that barn owl pair near my house manages this when they seem to be shrieking from sunset to sunrise is beyond me!
Their eyes are the final piece of the puzzle, and are pretty special in their own right:
Unlike our eyes, which are round and able to swivel in their sockets as a result, owl eyes are more conical, and set within deep sockets. They are firmly fixed in place, meaning the owl has to physically turn its head in order to see things off to the side. This might sound like a disadvantage, but when you consider that owls can turn their heads 270 degrees in either direction (a 540 degree arc!) it doesn’t sound like too bad a compromise.
The cornea and pupil of an owl’s eye are significantly larger than our own, as is the retina. Rod cells – the truly light-sensitive ones – are in far higher abundance than cones – the ones that detect colour – so owls generally have monochrome vision but are able to make use of the smallest amount of light available.
Owls occupy what is essentially a very difficult niche; that of a predatory night-bird. Their family has managed to overcome the obstacles associated with the niche in some of the most remarkable ways, rendering them incredibly efficient birds.
If the barn owl pair could just lower their volume a tiny bit in the coming weeks, I think there are more than a few of us who would be grateful for it, and we can then get back to appreciating the family properly!