Thursday, December 03, 2009

Blakeman on the Mystery Hawk and the Central Park Great Horned Owl-- Kinds of Feathers

Remember the Mystery Hawk on Karen Anne Kollings Gonzo Deck? I couldn't figure her out. Thankfully our Ohio Red-tail expert John Blakeman has waded in to help.


The accipiter in question is almost surely (95%) an immature female Cooper’s Hawk. The head profile just looks Cooperish, not as big or long as a goshawk.

Also, the covert feathers on the back appear too big and too few for a goshawk. Gosses have lots of smaller feathers there.

And yes, the white eyebrow is too indistinct for a goshawk.

And by the way, goshawks seem to be increasing in number in many parts of the East (and perhaps elsewhere). An increased number of them have been seen this fall in Ohio, along with a report of a new nest here. Ohio is not prime goshawk habitat, so it has been good to learn of the species’ apparent expansion here. It’s still very minor and my not persist. But it’s not merely incidental, either. Just too many new sightings compared to recent years.

–John Blakeman

Thanks John, for the 95% I.D. It had been bothering me that I didn't know what she was.

That's a relief.

Wonderful news about the Goshawk's expansion. I've had a portrait of a Goshawk in my bedroom for 20 years and I've yet to see one. Now perhaps with their branching out I'll get my chance.

Yes, finally we're getting to OWL FEATHERS!
I have to admit there is something particularly spectacular about the feather packages that owls come in. Part of it, I think, is the play of light on the myriad colors and then there is that fluffiness factor. It makes them look very tickle-able. Of course they aren't the least bit tickle-able but as we're speaking of feathers and tickling...


You don't pet a bird.

They've done all that work on their feathers getting every feather situated and they don't really want you squashing them.

You tickle a bird.

Of course the bird has to not mind being touched first off which completely leaves out most wild birds, but there are a few raptors in captivity that I've met that don't mind. According to Len Soucy of The Raptor Trust in New Jersey, "It isn't that raptors enjoy it particularly but some birds will let you do it anyway."

To tickle a non-raptor, use the tip of your index finger and gently go back and forth laterally on the tip to mid portion of a row of feathers on the birds neck or head. They particularly enjoy that area as they can't really groom those feathers themselves. If that is working, you can try working with your thumb and index finger rather like a beak would.

The Red-tails that will deal with a tickle, usually education birds or falconry birds, in my experience like their tickle on the wing about midway down, towards the front. That is if the owner says it's okay. Normally their feet will be restrained in those situations. And as always be alert to how the bird is feeling about the situation.

Years ago I knew an ornithologist that walked around the University with a Red Screech on his shoulder. That bird could be touched anywhere and even seemed to enjoy it. The British raptor expert, Jemima Parry-Jones also had a human bonded owl that went to class with her and according to report loved watching the proceedings and the company.


Contour feathers are the feathers closest to the air on the body, the wings (remiges) and the tail (rectrices).

Owls, at least the nocturnal ones, have a unique owl adaption on the leading edge of the primary wing feathers called the fimbriae (comb-like) or flutings. It's one of the owl's secret weapons. theory 1 is that instead of the sound of rushing air made by other birds when they fly due to turbulence, air rushing over the wings, the fimbriae break down that big turbulence into mini-turbulances which muffles the sound so we and the prey don't hear them coming. Or don't hear in time anyway.

Theory 2 is that the fimbriae shift the sound energy made by the wings to a higher frequency which the owl, we, nor the prey can hear.

Which made me wonder what animals had the best high frequency hearing and therefore might hear the owls coming. I looked it up and bats and some moths have the best high frequency hearing with the cat as runner up. I haven't read anything about owls eating bats but perhaps they do on occasion.

We know that a Great Horned Owl can on occasion take young/small cats. Which w0uld make one think that a cat's hearing wasn't up to hearing a GHO coming in time to run for cover. But there is a possible anecdotal contributing factor. When I was going to school in Wisconsin, I had an acquaintance who only took black kittens as pets because if she got a kitten of another color it "disappeared" due to the local owl. (Keep kitty in the house.) So did the owl just never see the black kittens or could black kitten hear the owl coming and so went into a freeze so it was never seen?

Also, and I hadn't really thought about this much until lately, the silent flying not only helps the owl's stealth approach but also allows the owl to locate, ie. hear the prey better when they aren't listening to a bunch of their own wing noise.
Note the specially designed feathers around and below the beak.
Many of those are filoplumes, an owl speciality. They look almost like hair and consist of a very fine shaft with a couple of short barbs on the end or no barbs at all. They are thought to be pressure and vibration receptors and hence are found around the beak and feet. They help the owl monitor not only what the prey is doing when nabbing it but also what the other feathers around the filoplumes are doing.

Right- Turkey feather and Left- is a feather off a cat toy so somewhat mysterious. But as the toy was made in China and from the look of it, the top portion is a dark green, I'm thinking possibly a duck or a pheasant?
As owls tend to have the soft fluffy look, you'd think they might have lots of down. (Down being a fluffy feather that is the bottom layer closest to the skin which conserves body heat.) It turns out that fluffy looking or not owls have very little true down, what they have is a kind of a two-in-one feather called the semiplume. Semiplumes fill in under the contour feathers and over the down if there is any. The above turkey and possible duck feather are semiplumes. The top portion is more like a contour feather and the bottom portion changes into downy barbules.

So what about that sort of facial disc area? In that area are filoplumes, the fine hair like feather but also a good number of bristles. Bristles are stiff like a cat's whisker but smaller. They have a very stiff shaft and only a few barbs at the bottom of the shaft or no barbs at all. Ever look at a bird's "eyelashes"? Those are bristle feathers which also occur around the whole eye area in the facial disc feathers as well as distribution under the beak.
Beyond the specialized facial disc feathers, there can also be specialized ruff, ear flap, and crown feathers.
And as we're talking about feathers, owls have an adaptation that allows them to do a nice preen job on the feathers on their heads that their beak can't reach. The two outer talons on a owl's foot have a sharp medial edge which turns them into feather combs. These particular talons do a lovely job of relocking the feather barbs which have become separated, giving the owls head a nice smooth surface which is better for dealing with wind resistance while flying.
A tidy owl is a marginally faster owl, and likely quieter too.
Donegal Browne

No comments: