Sunday, October 23, 2011

Northern Saw-whet Owl, captured!

Northern Saw-whet Owl, Aegolius acadicus, captured last night near Chillicothe, Ohio. Word is that these little micro-hooters are moving south out of their northern boreal forest haunts in good numbers. So, I headed down to Ross County and the site of a long-term banding operation on their second night of opening the nets this season, full of good owl vibes. It paid off; we snared an owl on the second net run of the night.

This operation was started about eight years ago by Kelly Williams-Sieg, in collaboration with Bill Bosstic and Bob Placier. That's Bob on the right, assisted by Randy Lakes. Once an owl is captured, it is transported to a nearby house which serves as the base of operations. Once there, the saw-whet is thoroughly inspected, data is collected, and the animal is ringed with a metallic band.

What is especially eye-opening to me about this particular banding site is the seemingly commonplace habitat. Two lengthy net runs are strung through young deciduous woods and brushy successional habitat, no different than can be found in scores of other sites in this region. Yet Kelly and crew have caught something on the order of 300 owls here. Northern Saw-whet Owls are, perhaps, the most common avian predator in the boreal forest, but until this work began no one had any idea that so many migrant owls passed through Ohio.

Last night's sole capture was, I believe, an after hatch year bird, sex indeterminate. There are a significant number of owls in which sex cannot be told for certain, as there is overlap in some of the characters that are used to sex the birds. He/she had to suffer the indignity of being stuffed in a cup for weighing. This individual tipped the scales at a whopping 87 grams. That's about three ounces - the same weight as a Blue Jay. The little bands used to ring the birds can be seen on top of the tool box.

Saw-whet Owls are incredibly mellow, and rarely protest the indignities foisted upon them in the name of science. Occasionally one will make its displeasure known by clacking its billl loudly, but ordinarily the owl will just stare curiously at the offending parties.

Perhaps the strangest data-gathering involves the black light treatment. Pigments known as porphyrins glow purple under the black light, and a skilled owl-reader can use the owl's glowback to help determine age. Apparently the presence of porphyrin in feathers is unique to owls, and its concentration reduces with age.

One trick that is always sure to elicit aahs from the crowd is the head rub. Just like cats, saw-whets seem to greatly enjoy a good rub behind the ears. If you take your finger and gently rub the animal, it'll invariably hood its eyes and push back against your finger as if asking for more.

Hundreds and hundreds of people have made the pilgrimage to this banding outpost and seen saw-whet owls firsthand. In the process of working an owl, people get the rare opportunity to see up close and personal the specialized morphology that allows owls to weave their deadly magic. We're looking at an ear in this photo, and it is proportionately massive in comparison to the owl's head. The ears are concealed beneath dense feathering on the sides of the head; we've pulled back the feathers to reveal one. Not only are the ears enormous but they are bilaterally asymmetrical - one does not occur at the same point on the head as the other. Offset ears allow for greater ability to triangulate on sounds, as the rustle of a mouse will reach one ear slightly before the other. The owl's brain is an exceptionally quick microprocessor and instantly tells the bird where the sound is coming from.

An unlucky rodent will probably never know what hit it, and this is why. We're looking at the leading edge of the primary, or flight feather. It is fimbriate, or fringed with small barblike extensions. This fringing muffles the air flow over the wing and permits the owl to aviate in near silence.

Once the mouse has been whacked, its chances of escape are nil. Northern Saw-whet Owls may indeed appear "cute" (nearly everyone describes them with the C word), but they are quite lethal. Their talons are llike little hypodermic needles, and they're bolted to powerful feet equipped with strong tendons that give the owl a viselike grip. Many a bander has slipped up in handling an owl, and had their flesh pierced by these talons. From my observations of the persons' reactions, it doesn't tickle. To a mouse or vole, the tickle of these talons would be far more deadly.

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2 comments:

Jessi said...

My family would LOVE to go to a banding someday.. What a cool adventure!

Anonymous said...

Interesting! I live in Clermont Cnty -- While I know Ross Cnty, a location given only as "Ross County" isn't helpful. Ross Cnty is fairly large....even 'near Chillicothe' isn't helpful.... so, can you say more precisely WHERE 'in Ross Cnty, near Chillicothe' we can find/visit/participate? Thank you.