[obol] Wigeon hybrids?...and molt sequences

[DAVID IRONS]

Earlier today Steve McDonald and Holly Reinhard posted reports of oddly plumaged wigeon in which they speculated that the birds might be hybrids.  I looked at the linked images provided by Holly and Steve and I believe these speculative hybrids are more likely molting birds.

In 2003 Steve N.G. Howell and others determined that unlike most birds, the definitive brightest plumage of ducks is attained through a pre-basic molt, and it is actually their basic plumage as opposed to the alternate plumage as previously believed.  This pre-basic molt occurs during the fall months as ducks transition from what has historically been called "eclipse" plumage.  Howell et al. determined that eclipse plumage is actually alternate plumage in ducks.  

Definition of Terms:

Basic Plumage -- In most species this is the dullest plumage carried through the winter months.  Attained through a pre-basic molt, usually starting in late summer/early fall.

Alternate Plumage -- In most species this is the brightest plumage or what is often referred to as "breeding plumage" and carried through the spring and summer months.  Attained through a pre-alternate molt, usually during late winter/early spring.

Eclipse Plumage -- Generally applied to male ducks, which shed their brightest plumage late in the breeding season and spend most of the summer and early fall looking somewhat like less colorful females.  

On Holly's bird, which she calls a Eurasian Wigeon or possible hybrid, I don't see any aspect which suggests American Wigeon parentage.  To me it looks like a male Eurasian transitioning from alternate (formerly referred to as eclipse) into basic plumage.  There is no suggestion of green in the head and the flanks are mostly gray.  I have seen couple transitioning Eurasians that looked virtually identical to this bird. 

Steve's bird is a little less certain.  However, I think the somewhat "golden" cast to the crown (white basic feather just starting to grown in) and the restricted green swoosh behind the eye (green feathers not fully grown in) are likely attributable to pre-basic molt, which is occuring at this time of year.  Typically, hybrid wigeon show fairly obvious characteristics of both species.  Steve's bird does not appear to have any cinnamon coloring on the head or gray along the flanks.  Aside from the slightly golden cast to the crown, this bird looks like a fairly typical transitioning American Wigeon to me.  I have also found that the whiteness of the crown on American Wigeon is variable and can on occasion look more cream-colored.

There is a nice exchange of letters in BIRDING (Vol. 39 Issue 1 ppg. 10-12) where Jessie Barry and Chris Benesh discuss the advances in the understanding of duck molt sequences.  
 
Dave Irons 
Eugene, OR   
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