How to I.D. and Age An Orange-crowned Warbler
Category: Birding at the Chico

This adult (orange crown feathers visible after blowing on the top of the head) Orange-crowned Warbler appears to be reading the IDENTIFICATION GUIDE TO NORTH AMERICA BIRDS Vol. 1 by Peter Pyle, the bird-banders bible. The book tells bird banders what to look at and what to measure in order to age a bird and how to separate it from look alike species. It also suggests one or two band sizes that should fit the leg of the species. 

 ORANGE-CROWNED                                                               OCWA
Vermivora celata                                                                           Species # 6460
                                                                                                       Band size: 0-0A

Species--From Tennessee Warbler (which see for separation from Phylloscopus warblers) by tl long (42-53; see Age/Sex); longest p - longest s 8-15 mm; upperparts olive to yellowish; distinct eye ring absent. Eastern birds from Mourning Warbler by much smaller size (wg 51-66, tl 42-53; see Age/Sex); undertail covs usually brighter yellow than the belly; legs blackish.

tl = tail, p = primary, s= secondaries, wg = wing, covs = coverts

The book then goes on to describe the different Orange-crowned Warbler subspecies, what to look at to determine molt limits, what to look at after wetting the top of the head feathers to see if the skull is ossified partially (this year's birds) or completely (birds older than one year), and then tells the bander what to look for on a bird to determine its age and what to look at to determine its sex

Posted by Bill M. on 09/15/2017
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