mantle color of ? Kelp Gull
S. Harvey Mudd, MD (shm@codon.nih.gov)
Thu, 18 Feb 1999 10:03:55 -0500
For what it is worth, I can report here on the impressions of two observers
of the color of the upper parts of the St Mary's County ? Kelp Gull in
direct comparison with a Great Black-backed Gull. Last Tuesday, Feb. 16,
while Bill Mauck, George Jett, Marion Mudd and I were studying the bird, for
at least 15 minutes it was perched about 10 yards from a Great Black-backed.
Both birds were sitting quietly, about 30 yards away and faced in the same
direction as we watched them through telescopes. Neither Marion nor I were
able to convince ourselves that we could be sure there was a constant
distinguishable difference in the dark tones of the upper parts of the two.
At times, depending probably on minor changes of position and incidence of
light, to our eyes either one could appear very slightly darker than the
other. This is not to say there is no difference at all. Admittedly the
sunlight was quite bright at the time (the interval during which the
comparison was made was probably between 9:30 and 10 AM), and minor
differences could have been washed out. We do think we can conclude that
any difference in the color tones must be subtle and may depend upon the
exact lighting conditions. Given the closeness of the tones we observed, it
is also possible that due to differences between individual Great
Black-backs, the apparent relative tones might depend upon the individual
Great Black-backed with which a comparison were made.
Harvey
____________________________________
S. Harvey Mudd
NIMH/DIRP/LMB
Building 36, Room 1B-08
36 CONVENT DR MSC 4034
BETHESDA MD 20892-4034
tel: 301-496-0681; fax 301-402-0245
email: shm@codon.nih.gov