[CT Birds] Rough-winged Swallow id.

[julian hough]

While debate about late Northern Roughwings continues, another species to consider, one brought up personally by Shai Mitra,  is Yucatan Rough-winged Swallow, previously unrecorded in the US but a potential candidate for vagrancy.
  see
  http://www.martinreid.com/Main%20website/roughwing.html
   
  Clinal nature of rough-winged swallows means that there are few distinguishing sub-specific characters obvious in the field that would differentiate out of range individuals. The Northern and Southern Rough winged Swallows may differ in the field as posted previously by Greg Hanisek. However, a third taxon ridgwayi, or Yucatan Roughwinged Swallow is regarded as a distinct species but most likely more difficult to separate from Northern than Southern would be. Basically the features that would distinguish these from Northern Rough-winged are:
   
  Pale loral spots
  larger and darker than NRSW
  Dusky undertail coverts (with dark spots)
  more forked tail
   
  These features are subtle and hard to see in the field on a flying bird, especially when lighting may affect how dark or light a birds' plumage appears in the field.
   
  A closer look at the birds at East Shore would be in order to check out these features, especially if any one of the bird's looks darker or larger (assuming all are not of the same species).
   
  Julian