A sexing tip also appeared for free in very abbreviated form in the Owl Research Institute's "The Roost" newsletter Nov 2011 (vol 15 number 1, page 3) which is free on the web. You can get it here:

http://www.owlinstitute.org/pdfs/ORI%20Newsletter%202011%20for%20web.pdf

The ID tip presented there (from the same Seidensticker work) is: female wings have more bars and male wings have more spots.

Which with a modifying adjective ("possible", "probable") this may be good enough for gis/gestalt birding (as opposed to accurate censusing). At least it's something to think about when looking at a Snowy.

> Here is some recent information on ageing and sexing these owls from www.frontierscientists.com, an Alaskan website. Note the article by Mat Seidensticker.

See

http://frontierscientists.com/2011/12/fast-food-golden-truck-and-admirers-lure-snowy-owl-to-burns-oregon/

Note Seidensticker tentatively assigns a sex to the owl from Burns, OR from photos.

> "Birders usually want to know: Is it Male or Female? The Burns (Oregon) Snowy has been called both. Denver Holt, an owl researcherhttp://www.owlinstitute.org/ who has spent the last 20 years studying the Snowy Owl up in Barrow, is cautious about identifying the sex. ?The more experience you get the more questions you have,? Holt says. Yet the Journal of Raptor Research Dec 2011, Vol. 45, No. 4: 290-303 has just published an article ?Sexing Young Snowy Owls? by lead author Mathew T. Seidensticker, co-authored by Jennifer Detienne, Sandra Talbot, and Kathy Gray, and Holt available at this link http://www.raptorresearchfoundation.org/publications/journal-of-raptor-research/current-issue.
>
> Seidensticker and fellow researchers based their paper on a study of 140 owls from 34 nests (at Barrow). Specifically they looked at a secondary flight feather #4 on the left wing. Then they compared their predictions with blood tests. The model that correlated their data said they were 98% correct, actually they were 100% right. In short what the secondary feather #4 told them was: the female owl had a marking that they called a bar because it touched the feather shaft, while the male had a marking they called a spot or blotch that did not touch the feather shaft."
>
> So I think that it is really important to understand how challenging it can be to age and sex these birds in the field. If Denver Holt is cautious, I would be too.
>
> Bud Anderson

I suspect in the original work the bar/spot on the fourth secondary was the only single property they measured that accurately correlated 100% with sex. Bud's caveats seems a wise one.

It's a shame the ORI doesn't put pre-prints of the papers they fund on their web site.

On Nov 16, 2012, at 2:31 PM, Bud Anderson wrote:

> Hi,
>
> I am told that the link I posted earlier did not work.
>
> So I'd suggest that you e-mail the people at the Peregrine Fund library. They will send you a PDF of the article if you ask nicely.
>
> Write to library at peregrinefund.org and request the following article.
>
> Sexing Young Snowy Owls
> Mathew T. Seidensticker, Denver W. Holt, Jennifer Detienne, Sandra Talbot, and Kathy Gray
> Journal of Raptor Research December 2011 : Vol. 45, Issue 4 (Dec 2011), pg(s) 281-289
>
> Let me know if you have problems. Regarding the article that is.....

--
Kevin Purcell (Capitol Hill, Seattle, WA)
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