Saturday was a perfect day for RE-fest - a festival of Green Living and Clean Energy in Austin last Saturday--which I helped organize and for which I was a presenter. After my workshop, I was able to catch part of the Audobon raptor presentation - and they happened to be talking about great horned owls --the dreaded predator of our farm. I gleaned some fascinating facts about great horned owls.
Great horned owls have a wingspan up to 5 feet and can take a prey that is 17 lbs! (They can take a Canada goose or a great blue heron, for instance.) I learned that owls do not have eyeballs- they have tubular eyes that are fixed in their heads. Their eyes are on the front of their face, so they have binocular vision, as we do, but cannot move their eyes like we can. It doesn't matter that they cannot move their eyes because they are able to turn their heads nearly around to the back by virtue of their 14 neck vertebrae (we have just 7 neck vertebrae). Owl vision is so acute thay can see in virtually total darkness -darker than nature gets, except for perhaps in the deepest recesses of a cave.
A boy from the audience was invited on stage to demonstrate how acute his hearing is. After blindfolding him, the presenter clapped her hands in a random pattern: to the left left, right, above, below, behind, in front. The boy did well identifying the source of the clap when it was to the side, but was not able to discern when it was from above or below. That is because human ears are symmetrically placed on either side of our heads; owls' ears are asymmetrically placed, one above and forward, one below and a bit back. This allows him to identify the direction of the sound and, by tilting his head until the sound is even in both ears, hone in on it precisely. In additon, his flat face acts sort of like a satellite dish, funneling sound toward the ears. Why would an owl need such acute hearing when he already has such amazing vision? For one thing, in winter he can hunt rodents that are underneath the snow purely by sound.
The third feature that makes an owl such a formidable hunter is his ability to fly silently. Two more kids were invited up on stage: the first spun a rope around in a circle sort of like a lariat and it made that whirring, whipping sound. The second child also whipped a rope around in a circle, but her rope had little yarn tassels tied at inetervals along the rope, imitating the uneven feathers of the owl's wings. Her rope was virtually silent! Although the silence is undoubtedly helpful for sneakingup on prey, the real benefit is so that it allows the owl to hear the prey- the sound of his feathers is not drowning out the sounds of the prey(The presenter noted that in Japan, they have duplicated this sound-reduction strategy to moderate the sound of high-speed trains!)
After learning all this I was pretty discouraged about our dilemma with the great-horned owl feasting on our chickens and only eating the heads. During the questioon time I asked whether it would be a good idea to leave the body of the decapitated chicken lying there --might the owl come back and finish him off rather than killing another bird? The naturalists said No, and the fact that the owls are only eating the heads of my chickens is an indication that they are VERY well fed. (Yup, I know they are well-fed - we have lost 25 chickens ot the owl in the past 5 or 6 weeks!)
Yesterday we took 50 more chickens to the poultry processor (that's another story...) We still have a few chickens left, but now I am very worried that the ducks and Chuck Dickens (the chicken who thinks he's a duck) are the most likely targets of the owl because the darn geese keep them wandering around the farm all night. So, the past three nights we have been herding the the goose/duck/Chuck Dickens flock into the garage and shutting them in safely until morning.
I suspect Chuck is secretly overjoyed to finally get a good night's sleep!