Tweeters,

There is absolutely no doubt this is a 100% Gyrfalcon. A similar bird like this showed up in Kansas and caused some confusion because of the coloration. I've laid out the reasons below so hopefully Alex can take some assured satisfaction in finding this spectacular bird.

Here are the reasons it is a Gyrfalcon not a Prairie Falcon:

- COLORATION - A Prairie Falcon would be brown to light brown in coloration such as these birds from Colorado (http://schmoker.org/BirdPics/PRFA.html) not gray like the bird in the photo.

- MOUSTACHIAL STRIPE - Prairie Falcons have very distinct moustachial stripes (even juveniles) this bird clearly does not, it has a smudgy gray auriculars just like the Gyrfalcon in this picture also from Colorado (http://schmoker.org/BirdPics/Photos/Raptors/GYRF7%2B.jpg)

- EYEBROW STRIPE - Prairie Falcons have very distinct white eyebrow stripes (even juveniles)
this bird clearly does not, it has a gray eyestripe

- BARRING ON THE TAIL - Barring on Gyrfalcon tails is comparatively strong when compared to Prairie Falcon barring. Even though the angle of the photo isn't ideal for observing this characteristic on the bird a distinct pattern of barring is evident.

- FLANK STRIPING - Juvenile Prairie Falcons (this is a juvenile falcon as it does not have yellow nares) have dark brown blotching on their flanks that lead into their dark axillaries (see this bird: http://schmoker.org/BirdPics/Photos/Raptors/PRFA8.jpg). Gyrfalcon has linear striping that does not blotch on the flank as is the case with this bird.

- UNDERTAIL COVERTS - Prairie Falcons have clean white undertail coverts. Gyrfalcons tend to have some striping on their undertail coverts. Again Alex's photo is not at the ideal angle but gray coloration is apparent on the undertail coverts.

- OVERALL BODY SHAPE - Prairie Falcons are fairly dainty falcons in build. In flight they resemble a big kestrel due to their slim shape. However, Gyrfalcons are more like the illegitimate offspring of a Peregrine Falcon and a Red-tailed Hawk. They are a big and bulky falcon and unlike other falcons that appear to taper towards the tail when perched Gyrs do not.The bird in this photo, at least to me, looks very bulky and does not taper in shape like a Prairie Falcon would.

I hope this helps. I would be interested to hear from those why they think it is a Prairie Falcon.

Cheers,



Tyler L Hicks
Master's Student
Washington State University - Vancouver

E-mail: tyler_hicks at wsu.edu
Website: www.thingswithwings.org

"Back off man, I'm a scientist!" - Bill Murray, Ghostbusters




> Date: Mon, 21 Feb 2011 07:47:37 -0800
> From: alexam at u.washington.edu
> To: tweeters at u.washington.edu
> Subject: [Tweeters] Re: Raptor ID help please
>
>
> Hi again,
> I've had 3 people say it's an immature gyrfalcon, and 3 say it's a Prairie
> Falcon (some have replied privately). Either would be a life bird for me,
> just wish I knew which one it was. I'll try to see if the friend who
> accompanied me got any photos.
>
> In the meantime, I'd love more folks to take a look at those below!
> Thank you kindly,
> Alex
>
> On Sun, 20 Feb 2011, A Mackenzie wrote:
>
> >
> > Hello,
> >
> > While birding the Skagit yesterday (2/19) I came across a raptor I couldn't
> > ID - I got two photos which are here:
> >
> > http://www.flickr.com/photos/mizmak/5461690419/
> >
> > http://www.flickr.com/photos/mizmak/5461690425/
> >
> > The bird was about 16-18 inches. It was in a turnoff on Moore Road just east
> > of where Best Rd meets Moore (near the bridge). There was a photographer
> > there when we arrived who had much better equipment but I didn't get his
> > name.
> >
> > Any help is much appreciated!
> >
> > Thank you kindly,
> > Alex MacKenzie
> > Seattle
> >
>
>
> --------------------------------------------------
> Alexandra MacKenzie
> Admissions and Curriculum
> Biostatistics Department, University of Washington
> Box 357232, Seattle WA 98195
> Phone: (206) 616-6790
> alexam at u.washington.edu
> _______________________________________________
> Tweeters mailing list
> Tweeters at u.washington.edu
> http://mailman2.u.washington.edu/mailman/listinfo/tweeters