Hi Tweets,

Doreene Linzell writes:

>I found Michael Price's comment very interesting about the yellow bill
>of a loon being diagnostic. Here in Ohio we have a "raging
>controversy" about a loon that came our way last spring.
>The bird did
>have a yellow bill. But, many of the other features did not match
>with a yellow-billed loon.

Well, to indulge my weakness for stating the obvious, if it's not a
Yellow-billed, it has to be a Common. So how do the field marks stack up for
either? What supports each species? You don't mention where the bird was in
its plumage sequence (first-year?). Would you post the description(s), and
the pro-and-con discussions (names excised, preferably) either to the list
or privately? Got my curiosity going.

>Photographs were taken and placed on the
>Internet for people to critique.

I did a websearch for Yellow-billed Loon (YBLO). Is the site still there?

>Some experts (that actually saw the
>bird) said that it was definitely not a YELO. Others felt that it
>was. There was even talk that the bird might be a hybrid Common
>Loon/Yellow-billed Loon. My question is since you folks have more
>experience with both of these species, have you ever seen a hybrid of
>these two species?

I haven't in over twenty years of looking (non-specifically) at lotsa loons,
so I'll have to leave that to others to answer. Sounds as though they're
pretty well separated, and that hybridism is extremely rare if it happens at
all. Earl Godfrey, in his Birds of Canada, Revised Edition, says that "The
respective characters separating the two appear to be trenchant, and there
is little or no evidence of intergradation shown in the considerable number
of specimens seen by the author. One probable hybrid speciment is known: a
Common x Yellow-billed Loon taken at Port Credit, Ontario, 7 December 1956,
is in the Royal Ontario Museum." Well, Earl sure covers both sides of 'it
happens/it never happens', doesn't he? '-)

My own minor contribution to this is to mention a few things that might be
useful here: first, that bill shape and length in non-adult birds is highly
variable in both species, and can suggest the other species very closely;
that immatures of either species aren't too choosy about how they hold the
bill, either; that by spring, there's a lot of feather wear on the Basic
plumage and a young Common can have a subtle buff-grey wash from abrasion
over its normal cold grey and black plumage that might suggest the paler,
warmer browns of the juv/Basic 1/Definitive Basic Yellow-billed *and* the
bill-color in a late-winter Common can be quite pale, with the blue-grey
washed nearly completely out, but it is always a grey shade of white, never
the yellowish-cast white to cream white of the Basic-plumaged Yellow-billed.
In addition, first-year Commons often become quite pale-faced. In some
postures in some lights, such a late winter/early spring young Common can
bring many a scan by scope or bins to a screeching stop. But the principle
of the rarity being obvious is almost always (sorry about the hedge) in play
here: a Yellow-billed Loon in any plumage is usually clearly what it is;
it's the late winter/early spring Commons that cause by far the most alarums
and confusions.

Kenn Kaufman writes up a sufficient quick-'n-dirty on separating the COLO
and YBLO. Kenn's descriptions of the species-diagnostic pattern difference
of dusky feathering at the bill bases are good.

A *far* better ID help is an article in British Birds, Identification of
divers (the UK name for loons--m), by R.H. Appleby, S.C. Madge and Killian
Mullarney (Aug 1986, Vol 79 No 8, pp 365-391). It's much more
comprehensively written and illustrated with many photographs and
illustrations showing each loon species (Red-throated, European-race Arctic,
Common and Yellow-billed) both on the water and in flight, with very
detailed descriptions and species accounts. There's comparative flight
profiles and flight behavior, descriptions of each species at various points
in its molt sequences from Juvenile on, as well as a general ID overview for
each. This article also contains descriptions of species-characteristic
behavior and ID similarities among the species and how to resolve them.

The only thing it doesn't have is a write-up on Pacific Loon (Gavia
pacifica), because at the time this was considered a subspecies of Arctic
Loon (G. arctica) that would never visit the UK, but its treatment of Arctic
is pretty definitive. If it was re-written to include Pacific Loon, and to
include any new info on loon ID and behavior, this article would be a great
one to reprint: it gives you *everything* you need for loon ID in
lucidly-written language in about twelve-fifteen pages of text. Shorebirds,
loons, jaegers, Handbook of the Birds of the Western Palaearctic,
whatever--The Brits are so damn *good* at this kind of thing (not to mention
affordable--however do they do it?).


Bob Norton writes:

>I rise to disagree that yellow bills mean Yellow-billed Loon . Here on
>the Olympic Peninsula 90% (a guess) of the winter loons with yellow bills are
>Commons.

Darn those guys at Bushnell, I warned them and *warned* them that those new
doubled gold coatings would cause trouble! Bob, I sure hope that 90% figure
for your guess is a typo, 'cause if most of your Common Loons have yellow
bills, it's time to share the wealth with the rest of us (or see next
paragraph, and further, ID confusion around Yellow-billed Loon). We are, of
course, talking about birds on which you can actually see the bill color,
shape and pattern, not birds too far out to do so.

Appleby et al. say:
"Out of summer plumage, the usual bill color of Great Northern [Diver]
(Common Loon--m) is very pale greyish white with a slight bluish cast. The
entire length of the culmen and at least a distal section of the cutting
edges are dark. Viewed at long range, it may impossible to discern any
darkness other than where it is most marked (usually the basal portion of
the culmen). On White-billed [Diver] (Yellow-billed Loon--m), at least the
distal half of the bill is very pale creamy white, usually with a
butter-yellow cast. The extent of dusky grey at the base of the bill is
variable, but is often dark along the top of the bill above and some way
beyond the nostrils. Even though the distal half of the culmen is pale, the
apparent extent of dark on the bill when viewed at moderate to long range
may be little different to [Common Loon]. Such birds should be checked for
traces of dark along the cutting edges of the distal half of the bill,
diagnostic of [Common Loon]."

So, as I said in the previous post, yellow bills, under most conceivable
circumstances (not likely to see a Common Loon elbowing aside the
hummingbirds and nosing around the nasturtiums and getting pollen on its
bill, for example), are *diagnostic* of Yellow-billed Loon: intrinsically,
it is *not* an overlap characteristic, whatever the pattern of dusky is. The
dusky being diagnostic is fine but it's not the only bill-based mark that is
so. Where the trouble arises is trying to ID a loon on bill color alone at a
distance where bill color is ambiguous, and that's damfoolishness. If you
don't see any other species-characteristic mark, you're guessing. Where the
authorities are unanimous is not to make an ID based on one feature *if
you're not seeing a definitive field mark or combination of field marks*.
This is simply sensible. But usually there's other marks to support the ID,
and it's possible to ID most birds at surprising distances using a
combination of marks.

Well, with respect to both Bob and Kenn Kaufman, in Vancouver BC, where YBLO
is a regular if rare bird in migration and winter, *categorically* 100% of
the birds seen to have yellowish to ivory/cream white bills have been
Yellow-billed Loons; equally categorically, 100% of the Common Loon bills at
any age here have been birds with bills various shades of blue-grey to
grey-white. Since I spend a good deal of each sea-birding day from September
to early May stalking the wily (and damn scarce) Yellow-billed, I have
fallen into every ID trap that juv/Basic-plumaged Common Loon has sweetly
handed me, and have finally learned my Common/Yellow-billed times table by
heart. After looking at thousands of Common Loons in every conceivable
plumage variation from juv on over twenty years, I've seen lots of
grey-white bills on COLO, but have yet to see a Common with a yellow bill.
Not impossible, but don't think there's many ID surprises left in this area.

The BritBirds article is the only place I've seen written up the field mark
of the pale neck with dark 'hourglass' pattern on hindneck on the juv
Yellow-billed where Common Loon is solidly dark from side-neck back. I've
seen that on at least four YBLO juvs and it's a good, easily-visible mark.

Here's one, though. Actually, in Vancouver BC, the major ID impostor of
Yellow-billed Loon at a distance is just about the last bird you'd think,
but I've seen it and it is really true, especially for the next few weeks.
The average arrival in Vancouver BC for YBLO is 9/26. In these warm days of
'Grandmother Summer', in the smoky haze on the water, you can see a large
bird floating in the distance near a group of recently-returned migrant
Common Loon families, pale yellowish bill held appropriately above the
horizontal, with pale head and sandy-brown longish neck, warm brown body.
Bing-*o*, you think, first juv Yellow-billed of the southbound migration.
Little too far out for plumage detail beyond the bill and overall color, but
the size and jizz are *perfect*. Hey, it's floating closer, time to pick up
those details in case the skeptics start yapping and ankle-biting, yeah,
that head color and neck are right on, man, yeah, and look at that bill,
really conspicuous, easy to tell 'em from Commons, eh?...hey, what the--!
Aww, jeez: juvenile Double-crested goddam Cormorant. It was a lesson, alright.

So that's about all I can think of. Hope to see that loon on the Web!

Michael Price The Sleep of Reason Gives Birth to Monsters
Vancouver BC Canada -Goya
mprice at mindlink.net