Yeah, don't believe it. This bears looking into, and I hope the data compiled by the Snowstorm project (http://www.projectsnowstorm.org/) might help shed some light on the subject. "Conventional wisdom" about darkness of markings being tightly correlated with age doesn't seem to be accurate. The Snowstorm folks are requesting submission of photos of flying birds so that they can assess the "molt limits" of the birds to assess age.
Molt limits are the obvious differences in age of the wing coverts that appear on birds (at least Passerines and owls) in their first year of life when they molt out of juvenal plumage. Most birds that age do not molt their flight feathers (primaries, secondaries, tail feathers), but do molt most or all of their body feathers. It appears that how many wing coverts a juvenile molts is variable, with many only molting some. Consequently, many (most?) young birds in their first year of life, after their first summer, show a mixture of fresh and old wing coverts and can be distinguished from adults this way. I don't know how easily owl feather generations can be distinguished, but you can see an example of a presumed immature Snowy Owl at projectsnowstorm (taken by Cornell grad Tom Johnson). The heavily barred and quite dark female Snowy Owl that came in to the Lab this week did not show any obvious molt limits, and I presume that despite its heavy markings, it was not an immature. Kevin -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Marie P. Read Sent: Friday, January 10, 2014 7:15 PM To: CAYUGABIRDS-L Subject: RE:[cayugabirds-l] age of Freeville Snowy Owl <Why are people calling the Freeville bird an immature? Well I'm looking at my Sibley guide as I type (I have NOT seen the Freeville bird yet) and he DOES base age somewhat on body plumage. Sibley has "First Year female" as densely barred but always with a white face. The "Adult male" is described as "some are nearly pure white". Adult female and first year male are described as intermediate between the previous two plumages. Just sayin' ;-)) Marie Marie Read Wildlife Photography 452 Ringwood Road Freeville NY 13068 USA Phone 607-539-6608 e-mail [email protected] http://www.marieread.com ***NEW*** Music of the Birds Vol 1 ebook for Apple iPad now available from iTunes http://itunes.apple.com/us/book/music-of-the-birds-v1/id529347014?mt=11 ________________________________________ From: [email protected] [[email protected]] on behalf of Kevin J. McGowan [[email protected]] Sent: Friday, January 10, 2014 7:03 PM To: CAYUGABIRDS-L Subject: [cayugabirds-l] age of Freeville Snowy Owl Why are people calling the Freeville bird an immature? To the best of my knowledge, Snowy Owls, and especially females, cannot be aged by body plumage. The Snowstorm website, http://www.projectsnowstorm.org/, is asking for photos of flying birds so they can look at molt limits in the wings to judge age. Based on the darkness of the individual I was good with calling it a female, but I saw nothing to judge age. Did I miss something? Kevin -- Cayugabirds-L List Info: Welcome and Basics<http://www.northeastbirding.com/CayugabirdsWELCOME> Rules and Information<http://www.northeastbirding.com/CayugabirdsRULES> Subscribe, Configuration and Leave<http://www.northeastbirding.com/CayugabirdsSubscribeConfigurationLeave.htm> Archives: The Mail Archive<http://www.mail-archive.com/[email protected]/maillist.html> Surfbirds<http://www.surfbirds.com/birdingmail/Group/Cayugabirds> BirdingOnThe.Net<http://birdingonthe.net/mailinglists/CAYU.html> Please submit your observations to eBird<http://ebird.org/content/ebird/>! -- -- Cayugabirds-L List Info: http://www.NortheastBirding.com/CayugabirdsWELCOME http://www.NortheastBirding.com/CayugabirdsRULES http://www.NortheastBirding.com/CayugabirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/[email protected]/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/Cayugabirds 3) http://birdingonthe.net/mailinglists/CAYU.html Please submit your observations to eBird: http://ebird.org/content/ebird/ -- ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3658/6981 - Release Date: 01/06/14 -- Cayugabirds-L List Info: http://www.NortheastBirding.com/CayugabirdsWELCOME http://www.NortheastBirding.com/CayugabirdsRULES http://www.NortheastBirding.com/CayugabirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/[email protected]/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/Cayugabirds 3) http://birdingonthe.net/mailinglists/CAYU.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
