The Loons are a small and ancient group of birds. They are specialized
fish eaters with dagger-like bills that spend most of their time in water.
They have lobed feet set so far back on the body that they are very clumsy
on land. All five species are restricted to the northern hemisphere and
all are migratory, spending the winter in coastal harbors and bays in temperate
climes. During the winter they sport a plain non-breeding dress like this
Common
Loon (left), but all species molt into a striking alternate plumage
before departing for the northern breeding grounds in spring, as has this
Pacific
Loon (below). Both of these photos were taken from wharves in Monterey
harbor, California, a great spot for loon watching. Indeed, my friend the
late great Roger Tory Peterson considered the loon photographic opportunities
here the finest he'd ever seen. |
The Pacific Loon (right) in Monterey Bay is not usually inside the harbor. Rather, flocks forage together beyond the kelp line. This makes it the most difficult loon to study closely (because it is the farthest offshore) but in truth it is by far the most common species in California. Some 90% of the thousands of loons that migrate up and down the California coast in spring and fall are Pacific Loons. It is closely related to the Arctic Loon G. arctica of the Old World. In breeding plumage its very pale gray nape is distinctive; in non-breeding plumage it lacks the white flank patch of Arctic; and at all times it has a decidedly thinner bill and more rounded head; good identification discussions of this field problems are in Reinking & Howell (1993) and Birch & Lee (1997), and I even published a small note (Roberson 1989). |
Knowing all the plumages of all five species of loons is important in California
where three species are regular; Arctic Loon is a super-vagrant; and the
fifth species, Yellow-billed Loon (left) is a rare but regular vagrant,
averaging perhaps 1-2/year. This particular individual has a special history
because it returned to the same spot -- about a half-mile offshore my hometown
of Pacific Grove -- for six consecutive years from winter 1993-94 to winter
1998-99. It would appear each year in November in full breeding plumage
(as in this photo) and would always be first spotted by Richard Ternullo
from his fishing boat. Then the loon would molt into basic plumage for
the winter but would change back into breeding plumage by the time in left
in March. |
Loon migration is impressive, and one also needs to learn the i.d.
of loons in flight. The basic-plumaged Red-throated Loon (below)
has a very thin bill, comparatively small feet, a pale plumage and a prominent
white flank patch.
 |
 There
has been much study of the breeding biology and ecology of the Common
Loon (right) [called the "Great Northern Diver" in the Old World].
It is the "state bird" of Minnesota and its weird echoing cry on the breeding
grounds is a classic sign of wilderness there and elsewhere in the forested
northlands. Because the use of motor boats on northern lakes negatively
impacts breeding populations, there has been much concern for its protection
recently (it also used to nest in northeast California long ago). The Loon
Society, now known as the North American Loon Fund, arose in the northeast
U.S. to help protect Common Loons. Now it but has broadened its interest
and support of research to all species. Check their web
site home page for many more details, including links to introductory
biology of all American species. |
The plumages of loons change dramatically from the wintering Common
Loon (at upper left) to the summer dress at right. Individuals change at
different paces (perhaps related to where they nest); oddly, the photos
at top left and at right were taken on the very same day in the Monterey
harbor where it is great fun to watch their molt during late winter and
spring. Juvenal plumage resembles the adult's winter (=basic) plumage,
but most species differ in having the back decidedly barred, as on this
juvenal Pacific Loon (below). Note that even in this plumage the
nape and back of the neck are paler than the dark sides to the neck, another
feature useful for separating Pacific from Arctic Loon.
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| I would be remiss if I didn't mention the current controversy about
the relationship of loons to other groups of birds. Traditionally, loons
are considered one of the oldest groups of birds and placed near the front
of the taxonomic order near grebes, penquins, and procelarids. Sibley &
Ahlquist (1990 and Sibley & Monroe (1990), using biochemical techniques,
considered them more closely related to shorebirds and alcids, and therefore
placed them somewhere in the middle of their listings (at the end of the
Charadriiformes). The most recent A.O.U. Check-List (AOU 1998) considers
the latter arrangement "highly controversial" and prefers to "retain [loons]
in their current position (i.e., at the front of the list) until their
relationships are resolved."
Photos: The basic-plumaged Common Loon Gavia immer was in the harbor at Monterey, Monterey Co., California, on 10 Mar 1983; the breeding-plumaged Pacific Loon G. pacifica was at the same spot back on 1 May 1978. The breeding-plumaged Yellow-billed LoonG. adamsii was just offshore Lovers Pt., Pacific Grove, on 13 Nov 1995 (from Richard Ternullo's boat). The flying Red-throated LoonG. stellata was over Monterey Bay in Nov 1985. The alternate-plumaged Common Loon G. immer was in the harbor at Monterey, California, on 10 Mar 1983. The juvenal-plumaged Pacific Loon was in a drainage ditch (a very odd spot for a loon) near Pajaro Dunes, Santa Cruz Co., California, in Dec 1982. All photos © 2000 Don Roberson; all rights reserved. Bibliographic note: There is no "family book" per se (there are numerous coffee-table "survey" books that include Loons among other waterbirds) although there are numerous books devoted to the Common Loon. An introduction to the family, with a few fine photos, is in Carboneras (1992). However, this particular family essay is weak when compared to other families in the Handbook of the Birds of the World series, and the author uses a very out-moded taxonomy which lumps Pacific and Arctic loons. Literature cited: American Ornithologists' Union. 1998. Check-list of North American Birds. 7th ed. A.O.U., Washington, D. C.TOP |