Kelp Gull (?) in St. Mary's Co. (long)
Rob Hilton (robert@csa.com)
Tue, 16 Feb 1999 12:09:38 -0500
This is being forwarded for Ottavio Janni, who is not signed up for
MDOsprey. On initial quick read-through, I can't think of anything to add.
Except that Dwight's Gulls monograph indicates that Kelp Gulls can have
visible head streaking in the adult non-breeding (=definitive basic)
plumage. How visible I need to look up tonight.
Best,
Rob Hilton
robert@csa.com
Bethesda, MD
+++++++++++++++++++++++++++
Here are some more notes/thoughts on the possible Kelp Gull in St. Mary's
county. Rob Hilton, Lisa Shannon and I watched this bird on Feb. 14 from
9:30 to 11:15 AM, and again on Feb. 15 from 9:30 to 3:30, along with Dave
Czaplak and Mary Ann Todd, and after lunch, by about a dozen other birders
as detailed in Phil's post. I am pretty confident that all gull species
except for -intermedius- (and possibly -intermedius/graellsii- intergrades)
Lesser Black-backed Gull (LBB) and Kelp Gull can be ruled out, and most of
the characters shown by the St. Mary's Co. bird are a better match for Kelp
Gull. I am reasonably confident that -fuscus- Lesser Black-backed can be
ruled out on structure alone, as -fuscus- is the smallest, thinnest billed,
longest winged subspecies of LBB and I think structurally the St. Mary's
bird is too bulky and thick-billed for a Lesser Black-back, except perhaps
for a large -graellsii-. I am not aware of any confirmed records of -fuscus-
in N. America. I think -graellsii- can be safely ruled out on mantle color.
Size: We watched the bird on Saturday in close proximity to Herring Gulls
(HEGU), while on Sunday it spent most of its time by itself. My general
impression is that it is about the size of Herring Gull, or slightly
smaller. This however can change dramatically according to posture and to
which Herring Gull it is next to. On Sunday we watched the "Kelp" Gull
chase off a first-winter HEGU, and the Kelp looked distinctly larger than
the HEGU. We then watched chase off an adult HEGU, and the Kelp looked very
slightly larger than the HEGU. It then flew into the water and landed next
to another HEGU, and all of a sudden the Kelp Gull looked tiny (the HEGU
must have been a very large one)! Generally, I feel the bird is about the
size of a small Herring Gull, though its bulky appearance makes it seem
larger when it is off by itself. Size is good for Kelp Gull, which averages
slightly smaller than HEGU. I think size is OK also for a large
-graellsii-LBB. Note however that -intermedius- LBB averages smaller than
-graellsii- (87% of body size according to the article in Birding), so if
the St. Mary's Co. bird turns out to be intermedius it would be a very large
one.
Structure: My very first impression upon seeing this bird on Saturday was of
a Great Black-backed Gull (GBB) with yellowish legs, and immediately
afterwards I thought "Wow! It has a huge bill for a LBB!". Generally I feel
this bird looks bulkier, deeper chested, and thicker billed than just about
any LBB I've ever seen (and I only have experience with -graellsii-, which
averages larger and thicker billed than intermedius). I and most other
other people I discussed this bird with felt that the third white primary
tip on the folded wing (or P7) fell even with the tail tip. This primary
projection seems to be short for intermedius, in which the fourth white tip
on the primaries should fall even with the tail tip (which is however what
Phil and Marshall's notes indicate). From photos and videos I've seen the
primary projection looks OK for Kelp Gull. The head shape was tricky to
judge as it varied a lot with posture, and a few times it looked pretty good
for LBB. However, at other times it didn't and I think it was consistent
with photos and videos of Kelp Gull that I've seen. The bill shape was the
first thing that I saw on Saturday that made me suspect that this bird may
not have been a LBB (Rob keyed in on the leg color first). It appears to me
to be thicker than any -graellsii- I've ever seen, with a pronounced
gonydeal angle. While the bill looks generally of even thickness throughout
its length, it appears to be thickest at the gonys. The sharpness of the
gonydeal angle may be a good clue in distinguishing it from LBB, as Kelp
should have a sharper gonydeal angle, but I'm not really comfortable judging
this feature. While many Kelp Gull photos I've seen show an even thicker
bill than the St. Mary's Co. bird, some show a very similar bill shape. In
conclusion I think bill shape and general structure favor Kelp more than
they do -intermedius- LBB, and completely rule out -fuscus- LBB.
Mantle color: Very dark. In general, the mantle seemed very similar to
that of GBB, and perhaps very slightly paler. This impression changes
according to light conditions: there are times when the mantle looks almost
blackish, and times (rarely) when it looks almost pale enough for a
dark-backed -graellsii-. However, the only time that we actually saw this
bird right next to a GBB, the "Kelp" Gull's mantle looked slightly but
distinctly *darker* that the mantle of the GBB (this would be a very good
character for Kelp Gull). In flight the entire upperwing looked very dark
with no noticeable contrast with the black on the primaries. The tertial
and scapular crescent were quite prominent, and on the folded wing the
tertial crescent extended noticeably onto the secondaries. In conclusion I
think the mantle is dark enough to rule out -graellsii-, perhaps on the dark
side for -intermedius- (but still OK), and pretty good for Kelp. I think it
would be helpful to observe this bird on an overcast day, as well as having
more extended observations of it next to a GBB, to better assess mantle
color.
Wing pattern: The upperwing looked very dark gray, with no noticeable
contrast with the black on the primaries. The bird had a fairly thick,
conspicuous white trailing edge on the secondaries, extending perhaps onto
the inner primaries (I didn't look for this). The only white mirror was a
small one on P10, and several of the primaries had noticeable white tips.
At close range and with a telescope one could see two tiny white tongues on
P5 and P6 when the bird stretched its wings out. This pattern is an
excellent match for that shown in Jon Dunn's Large Gulls video (close-up
still of Kelp Gull's wing pattern). Apparently, some -intermedius- can show
a similar wing pattern with such a small white mirror on P10 only, but they
should be a small minority. On the underwing, the flight feathers appear
very dark (except for the broad white trailing edge on the secondaries),
again with a small white mirror on P10, and white tips to some of the
primaries. The wing pattern therefore seems to be a very good match for
Kelp Gull, and could also be shown by a small minority of -intermedius- LBB.
Head and body plumage: At first glance the head and body appear pure,
gleaming white. Upon closer inspection however there are some small,
sparse, inconspicuous dark streaks on the head, concentrated on the nape and
extending even more faintly on the crown. The photo of the Texas Kelp Gull
which appears on the cover of Field Notes (Vol. 51, No. 3? I don't have it
with me right now [winter 1997? with Ned Brinkley's hurricane birds
article--Rob]) shows a very similar pattern of head streaking. However,
as Kelp Gulls are always supposed to show clean white heads, it would be
useful if anyone had a photo of the St. Mary's bird earlier in the winter.
If any such photos show more extensive head streaking, the argument in favor
of Kelp Gull would be weakened (this is potentially the *only* feature
inconsistent with Kelp Gull). I think most LBB (at least graellsii) should
show more head streaking than this bird now, but some LBBs can certainly
look pretty white headed by mid-February, so this might be a moot point (and
anyway intermedius should on average have less head streaking than
graellsii).
Soft Part coloration: As Rob immediately noted, the leg color is the single
biggest point against this bird being a LBB of any subspecies. Depending on
light, the legs look anywhere from dull grayish-green to yellowish with a
gray-green tinge. Maybe the best description of leg color, as Dave Czaplak
put it, is "split-pea soup" . I would say that a grayish element is
noticeable 100% of the time, and a greenish element is noticeable 90% of the
time (and is usually quite conspicuous). I have never seen a LBB with a
greenish tinge to the legs, nor have I ever seen a photo of one. Nowhere in
the literature that I've checked (need to do more checking) have I seen it
mentioned that LBB can show greenish legs. Grant's Gull book states than a
small minority (as many as 3% in some large samples) can show a grayish
tinge to the legs, but he never mentions green. The leg color however is an
excellent match for Kelp Gull, and resembles very closely the leg color of
the Kelp Gull on the cover of Field Notes. Jon Dunn's Large Gulls video
stresses leg color as an excellent field mark for Kelp Gull. I am not sure
that leg color completely rules out LBB, but if this bird is a LBB then it
certainly is a very odd one. One the other hand, leg color seems to be an
excellent match for Kelp Gull.
The bill is fairly bright yellow, with a large, diffuse red spot at the
gonys and a slightly paler tip. Above the red spot, there is a faint but
noticeable orange "flare" on the upper mandible. Perhaps this is
inconsequential, but a similar flare can be seen on the photo of the Texas
bird on the cover of Field Notes, as well as on some of the Kelp Gulls in
Jon Dunn's video, and on one photograph in Steve Howell at al. article on
Kelp Gulls in the Yucatan in "The Euphonia"[Volume 2, No. 4, Winter 1993,
pp. 71-80--Rob]. The orbital righ is orange or reddish orange (both LBB
and Kelp should have red or reddish orbital rings), and the eye is a pale,
greenish/graysh/yellowish (not brighter yellow as on most LBB). In fact the
soft part coloration of the St. Mary's co. bird matches that of the Texas
Kelp Gull strikingly well (several observers commented upon this).
In conclusion, I think the bird's features match Kelp Gull better than they
do -intermedius- LBB, and that the other subspecies of LBB and other gull
species can be safely ruled out. If this bird is an -intermedius- LBB, than
it has an unusual wing pattern (but still consistent with -intermedius-), is
exceptionally bulky and thick-billed even for -graellsii (and even more so
for -intermedius), and has an extraordniarily unusual leg color for any LBB.
The combination of an -intermedius- LBB showing all three of these features
seems remote, but not impossible. I would have no doubt in calling this
bird a Kelp Gull if it had an even thicker bill, even darker-mantle, and
pure white head (this last point is potentially the only serious problem
with Kelp Gull), but as it is I think it is much more consistent with Kelp
than with LBB. However, I have no field experience with either Kelp Gull or
-intermedius- LBB (plenty with -graellsii- though), so these comments are
only based on my interpretation of what I've read and the photos/videos I've
seen and the birders I've talked to.
There are more photos of Kelp Gull on the web at:
http://www.west.net/~dj/domi_d.htm,
and there is a Kelp Gull ID article, based on the birds in Lousiana, at:
http://www4.linknet.net/LOS/los_news_181_98july.htm.
If anyone has access to the Handbook of Australian, New Zealand, and
Antarctic Birds (HANZAB) Vol. 3, I suspect this is the best place to look
for detailed plumage descriptions of Kelp Gull, and would be an essential
reference for identifying the St. Mary's Co. bird. I don't have access to
it.
Ottavio Janni
Washington DC
ottavioj@iadb.org