Yesterday, along Accotink Creek, Fairfax County, I saw many Barn Swallows
and three Northern Rough-winged Swallows feeding low over the water of the
creek itself and of an adjacent pond. Two of the rough-wingeds were
completely 'normal', and served as a good comparator to the third example.
This third example was virtually dark brown all over; otherwise it was
identical to the 'normal' birds in size, structure and behaviour. Its upper
parts were a bit darker than the 'normal' birds, but below it was
substantially darker, almost to the point where there was no difference
between the upper and lower parts. Very close study did show that the brown
was slightly lighter in this bird in those parts where a 'normal' bird is
quite light. The undertail coverts were not white in the third bird, but
were slightly lighter than the (short) undertail itself.
I can find no reference to any race of Northern Rough-winged Swallow with
these characteristics. My presumption, therefore, is that the third bird was
just an extreme individual variation, in some way melanistic.
I would welcome comments on the above. In particular, are such dark examples
often seen?
Stephen Eccles
