[MDOsprey] New Information on the Yellow-billed Loon
PObrien776@aol.com
Sun, 7 Nov 1999 17:54:09 EST
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I have revised my earlier description of the YBLO based on research I did
today while the Redskins were tanking. I think this will help.
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Yellow-billed Loon=0DPatuxent River Opposite Seabreeze Restaurant =0DSt. Mar=
y's County, MD=0DNovember 4, 1999=0D=0DObservers: Paul J. O'Brien, Maryland=
=0D John Gatchet, Idaho=0D=0DAt approximately 12:30PM I obse=
rved a bird with the overall size and shape of a Common Loon, but exhibiting=
a light yellow bill, floating, preening and occasionally diving in the rive=
r near the Calvert Co. shoreline. It was located at the south end of a larg=
e grassy area, the southern of two such grassy areas on the opposite shore. =
The day was clear and bright with the sun high but behind me. My attention=
was first drawn to the bill which stood out prominently, even at such a gre=
at distance. I was using a Swarovski AT 80 HD spotting scope at 60 power. =
Initially there was some shimmer that subsequently diminished. There were =
four Common Loons working the near shore, but they never approached the YBLO=
for direct comparisons.=0D=0DOverall the bird appeared to be in mid-molt fr=
om alternate to basic plumage. The crown and nape were dark chocolate brown=
which did not contrast with the brown back. The throat and foreneck were w=
hitish with a noticable dark brown neck ring just above the water line. The=
brown crown and nape extended below the eye and down the sides of the neck =
so that the auriculars were still in a dark field. Thus the dark auricular =
spot was not yet visible. The distance was too great to discern the buffy s=
calloping on the back mentioned by Charlie Muise on his first observation of=
Nov. 3, nor did I notice whether the high point of the back was over the sh=
oulders or further back. The outstanding feature of the bird was its bill, =
which was thick at the base with an apparently straight culmen. The lower m=
andible was straight for about half its length exhibiting a sharp gonydeal b=
reak upwards, thence straight to the tip. The entire length of the bill was=
straw yellow with what appeared to be dusky areas near the base of the culm=
en and the base of the lower mandible at the throat. To accentuate the upwa=
rd thrust of the lower mandible, the bird held its bill slightly above horiz=
ontal the entire time.=0D=0DAt about 1PM John Gatchet arrived to photograph =
the Kelp Gull. Having spent many years along the northwest coast he had see=
n many YBLOs and immediately confirmed the identification. After about 10 m=
inutes the bird began diving repeatedly and thereafter spent very little tim=
e on the surface, which John noted was typical YBLO behavior, and of the YBL=
O I observed Dec. 26, 1997 in Oswego, NY. It worked its way upstream past t=
he northernmost grassy area to a pair of docks. Its surface appearances las=
ted only a few seconds, not enough time to get it in focus. Finally, about =
2:55, it took off and flew far downstream. At first it gained altitude and =
was well above the tree line, passing two signal towers, then descended, onl=
y to be lost from sight when it went below the tree line. The distance coul=
d have been consistent with the mouth of St. Leonard's Creek, where it may h=
ave been seen the next morning by Greg Miller. In flight the bill again was=
the most outstanding feature, but there appeared to be two dark brown rings=
on the fully extended neck. The entire underside was white and the feet pl=
us an equal length of tarsus protruded beyond the tail tip. Oddly, the feet=
and tarsi appeared dusky pinkish. Whether this was a trick of the lighting=
or is some age or gender related feature is not clear. The flying bird res=
embled a Common Loon in size and shape but the flight seemed more ponderous.=
The entire upper surface appeared uniformly dark. I did not notice whethe=
r there were white primary shafts.=0D=0DClarifications added later:=0D=0DReg=
arding the intermediate stage of molt that I suggested, in A Field Guide to =
the Rare Birds of Britain and Europe, Harper Collins, 1991, page 27, the aut=
hors (Lewington, Alstrom and Colston), in discussing plumages of the White-b=
illed Diver (YBLO), say the following: "Full winter plumage is often not rea=
ched until late in the autumn/early winter." This would be consistent with =
the molt condition of the bird we observed.=0D=0DI should have mentioned th=
at, in flight, the bird continued to hold its bill above the horizontal and =
that the bill stood out as large, prominent and light yellow.=0D=0DAlso rega=
rding the flying bird, I noted that the feet and extended tarsi were a dusky=
pink color. I consulted Ralph Palmer's Handbook of North American Birds, Y=
ale Univ. Press, Vol. 1, page 36 and his discussion of the definitive altern=
ate (i.e. breeding) plumage of YBLO contains the following statement: "Legs =
and feet dark grayish brown on outer side, pale grayish flesh on inner and o=
n webs, the last with pinkish tinge." In his description of Common Loon on=
page 22 he says: "Legs black on outer side paling to medium gray on inner; =
webs of feet dark with flesh-colored centers." Although silent about other =
ages and plumages of YBLO, Palmer says on page 22 regarding definitive basic=
plumage of COLO: "Legs and feet as in Def. Alt. stage." I distinctly saw a=
pink tarsus and prominently pink feet, which should rule out COLO, assuming=
that there are no dramatic changes in either species during molt to basic p=
lumage. =
=
=0D=0DI should note that in stating that I did not =
notice white primary shafts, I actually didn't think to look for them and, b=
esides, I was busy studying the bill and the curious pink legs and feet.=0D=
=0D=0DPaul J. O'Brien=0D12 Duke St. South=0DRockville, MD 20850-1014=0D301-4=
24-6491=0Dpobrien776@aol.com
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