Monday 16 March 2015

Philadelphia Vireo x Red-eyed Vireo

apparent Philadelphia Vireo x Red-eyed Vireo hybrid, Southeast Farallon Island (California, USA), 7th September 2008 - copyright Matt Brady
(photo ID: 2121)

This unusual hybrid was present from 7th to 13th September 2008 and was written up in Western Birds 41:4 (Terrill, Tietz and Brady, 2010).  I've not seen the full article but an abstract is available online.  This points out how seldom Vireo hybrids are reported, this one in particular being reported just twice before.  It was intermediate between the two presumed parent species in breast colour, head pattern, head shape and measurements.  The wing structure apparently eliminated Warbling Vireo and the South American form of Red-eyed Vireo as possible parent species.  This bird was also written up on the Los Fallarones website, and this provides a little more detail and a couple more photos.

Philadelphia Vireo Vireo philadelphicus
Red-eyed Vireo Vireo olivaceus

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