Tuesday 17 June 2014

Tree Swallow x Violet-green Swallow

Tree Swallow x Violet-green Swallow hybrid, Port Susan Bay, Snohomish County (Washington, USA), 1st August 2010 - copyright Steve Mlodinow
(photo ID: 1494)


This hybrid has not been reported before although a mixed pair once attempted to nest in Illinois.  The lack of reports probably has more to do with how difficult they are to detect than their actual rarity but Steve did really well to pick this one out.  He describes the intermediate rump pattern, the Violet-green like markings on the face that is dark with a masked effect like Tree Swallow and dark along the flanks like on Tree Swallow.  Its tail is shorter than on Tree Swallow (central rectrices barely extending past the upper tail coverts in flight) and no Tree Swallow should show this much white on uppertail coverts. Pointing away from aberrant Violet-green Swallow are the dusky flanks,  limited white on its face and the odd rump patch shape.



Tree Swallow x Violet-green Swallow hybrid (same bird as in phot ID 1494 above), Port Susan Bay, Snohomish County (Washington, USA), 1st August 2010 - copyright Steve Mlodinow
(photo ID: 1492-1493)


Tree Swallow Tachycineta bicolor
Violet-green Swallow Tachycineta thalassina

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