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Better Birding
Tips, Tools, and Concepts for the Field
By George L. Armistead, Brian L. Sullivan PRINCETON UNIVERSITY PRESS
Copyright © 2016 Princeton University Press
All rights reserved.
ISBN: 978-0-691-12966-2
CHAPTER 1
Waterbirds
Loons
Swans
Mallard and Monochromatic "Mallards"
White Herons
Waterbirds in this case are a general grouping of birds that are not particularly coastal but are generally large and rather obvious and so good subjects for study. They provide a good starting point for a more considered examination, as one or more species are seen nearly throughout the ABA Area. While plumage characters are of course helpful, plumages are generally simple, but structure, range and habitat, and behavior are important keys to examine.
Loons
Red-throated Loon (Gavia stellata)
Pacific Loon (Gavia pacifica)
Arctic Loon (Gavia arctica)
Common Loon (Gavia immer)
Yellow-billed Loon (Gavia adamsii)
First Breeding: ~2– 4 years old
Breeding Strategy: Seasonally monogamous; solitary, territorial
Lifespan: Over 20 years
Graceful aquatic birds, loons are pursuit divers that propel themselves through the water with powerful webbed feet. Awkward and vulnerable on land, they are at home in the water, nimbly seizing fish using their powerful, dagger-shaped bills. They typically make land only to breed, nesting primarily across the high Arctic and boreal forest, building their nests at the edges of lakes or on small islands within lakes. They winter mainly in coastal marine waters, migrating along both coasts during spring and fall. During migration along both coasts (mainly March– April, November–December), loons become more social, sometimes aggregating in large, loose flocks (they do not fly in V formations). If you watch at coastal migration points you may find opportunities to study large numbers of loons in a relatively short time. There, most loons are seen in flight or at a distance, and this is a great way to learn the GISS of each species. Coastal locations hold the largest numbers in migration and winter, but loons can be found on any large body of open water, fresh or salt.
All five of the world's loons occur in North America, and also in parts of temperate and Arctic Eurasia (where they are known as "divers"). Common and Yellow-billed loons are closely related, and they have a similar large build. Arctic and Pacific loons would appear closely related based on their general similarities, but Pacific may actually be more closely related to Common and Yellow-billed. Red-throated Loon appears to be more distantly related to the others, yet all five species share the genus Gavia.
Loons are confused mostly with each other, but occasionally they are mistaken for grebes, mergansers, and especially cormorants. While beautiful and distinctive in breeding plumage, winter loons are more challenging identification subjects, clad in subdued grays, black, and white. At close range most loons are relatively straightforward, and a good study of head pattern, bill shape, and general plumage characters will help confirm identification. But loons always prefer open water, so distance and visibility often complicate identification. In addition, immature loons show variable and confusing plumages. Some one-to two-year-old loons oversummer on the wintering grounds, and these immatures can be especially difficult to identify because of age-related plumage variation and muted plumage patterns from sun bleaching or wear.
Common Loon breeds farther south than the others on wooded lakes across the northern United States and Canada, so it is particularly familiar to North American birders. It is a Hollywood favorite, and its call is frequently inserted into movie soundtracks to denote wilderness of any kind — often including, most inappropriately, the jungle! Common Loon's elegant features and distinctive voice lend it a mysterious and popular place in human society. Its likeness appears on the Canadian one-dollar coin, affectionately known as the "loonie." Indeed, the mournful wails of Common Loon are among the most moving sounds in the animal kingdom.
Hints and Considerations
• Common Loon is the default species inland or along the Gulf Coast. Red-throated Loon is rare inland, but common along both the Pacific and Atlantic coasts. Pacific Loon is rare inland and on the Atlantic Coast. Arctic and Yellow-billed loons are rarities anywhere outside Alaska, and scarce even there.
• Structure is key in loon identification, for all ages and plumages. Focus on the bill, head, and neck. Note the plumage pattern (light vs. dark areas) of the head, neck, back, and flanks.
• It is helpful to think about a mystery loon as belonging to one of two groups: "large loons" or "small loons." Generally, loons are big birds, but Common and Yellow-billed loons are especially large, with blocky heads, heavy bills, and robust bodies. In flight they flap more slowly than smaller loons (consider wind), have thicker necks and big feet, and at times hold their bills agape. The "small loons," Pacific and Red-throated, are slimmer overall and smaller billed, with sleek heads and necks. Arctic Loon falls somewhere between the two groups, with males quite large and heavy, and females approaching Pacific Loon in structure. Identify any putative Arctic Loon only with great care.
• All loons may "uptilt" their head or bill, but Red-throated, Yellow-billed, and Arctic loons do so most frequently. Common and Pacific usually hold the bill more horizontally.
• Immature loons wander more often than adults and are confusing, especially in summer, when feather wear, bleaching, and patches of adult breeding plumage confound identification.
Identification
Males and females are similar, but males average slightly larger. A loon's plumage varies depending on both season and age. In all species except Yellow-billed, breeding birds show black bills, while nonbreeding and immature birds have grayish bills with a darker culmen. Below, breeding plumage is described briefly first, followed by nonbreeding and immature plumages, as appropriate.
Adults are categorized as being in either breeding or nonbreeding plumage. Immatures attain adult appearance in the third fall, acquiring full breeding plumage in the third spring. Distinguishable plumages include: juvenile, first spring/summer, second winter, and second spring/summer. Second-summer loons appear highly variable, with some looking similar to winter adults, and others appearing similar to breeding adults but often retaining signs of immaturity (e.g., white blotches on face/neck). Second-winter loons are often indistinguishable from adults in the field.
While determining the age of loons is helpful in identification, all individuals are best identified based on structural characters, regardless of age. The species are ordered from smallest to largest.
RED-THROATED LOON: Our most distinctive loon, Red-throated is also the smallest and slimmest, with a small head and bill, and an almost serpentine appearance in the water. Only slightly smaller than Pacific, the most likely confusion species in the West, Red-throated can also be confused with the larger and bulkier Common Loon. On the water, its pinhead with strongly sloped forehead and flat crown, its skinny neck, and its usually uptilted bill are good indicators. In flight, the wings are slender and swept back, and the head is held low, often lower than the body, but at times bobs almost rhythmically with the wings. The wingbeats are noticeably faster than in the larger loons. Red-throated's overall paler appearance is also noticeable in flight. This is the only loon that can take flight from land, though this is seldom observed.
Breeding: More uniform and dark backed than other breeding loons, these have a dark chestnut-brown throat contrasting with a gray head, and white upper chest and underparts. Their breeding habitat differs from that of other loons in that Red-throateds prefer small, fishless ponds and lakes, from which they commute to larger lakes or coastal areas to forage. Breeding birds frequently give a croaking call when flying. Adult nonbreeding: These are paler overall than other loons, especially on the face, neck, and sometimes also on the flanks (but the latter is posture dependent). They are white faced, usually with white surrounding the eye, or at least rimming the front of it. Red-throateds have a narrow, dark crown. There is some white flecking on the back, but the "spots" are fine and very small (tough to discern at a distance); other adult winter loons have largely dark, unmarked backs. Compared to Pacific Loon, it shows less contrast between the extensively pale foreneck and the darker hindneck, and the hindneck and upperparts are less blackish and more grayish. Immatures: In Red-throated, a juvenile-like plumage is held through the end of a bird's first summer. These appear similar to nonbreeding adults but are more gray faced, and drabber gray overall, showing little contrast between the whitish foreneck and the pale gray hindneck. Some first-winter and especially first-summer birds can be very pale on the neck, at times appearing nearly entirely white headed at a distance; some can retain an overall gray-headed and gray-necked appearance (similar to fall juveniles) through the first summer. For nonbreeding and immature birds, the frequently upturned bill may accentuate the pale throat/foreneck and the stretched-out, rangy appearance. In flight, they appear mostly pale necked, while Pacific Loons appear mostly dark necked, with a more isolated whitish throat patch.
PACIFIC LOON: This medium-small loon has a compact build that usually shows a smoothly rounded crown. It is both more marine and more social than the others, at times migrating in flocks, sometimes 1,000+ strong. Extremely similar to the rare Arctic Loon, it overlaps in North America far more often with Common and Red-throated loons, so it is more often confused with those two species. Compared to Common Loon, Pacific is slimmer and more compact, with a rounded crown and finer bill. Pacific has an elegant carriage and shows a straight, even, dagger-shaped bill; when swimming it holds its bill horizontal (rarely uptilted). In flight Pacific is more often confused with Red-throated, but Pacific appears darker and thicker necked, with a slightly bulbous head and broader wings. On flying birds, the head is held even with the body, or just below it. Breeding: The contrasting silvery-whitish nape/hindneck combined with the round crown is distinctive from quite a distance. The face is dark, the bill is black, and the black upperparts are noticeably spotted white, especially on the scapulars and upper back. The dark throat usually appears black but occasionally shows a greenish or purplish sheen. At reasonably close range, white vertical neck stripes are apparent. Note that these are cut off from those on the shoulder, chest, and sides by the black from the throat, which touches that of the upper back (compare with Arctic Loon). Breeding occurs mostly in small or medium-sized tundra ponds (again compare with Arctic). Nonbreeding/Immatures: Nonbreeding adults and immatures resemble one another somewhat. Juveniles, especially when fresh in fall, show nice pale whitish fringes on the back and scapulars, whereas adults are more evenly dark above. Nonbreeding Pacifics are generally darker overall than other loons (ignoring Arctic Loon for the moment; see below); all are dark headed and dark necked, with a dusky face and a dark cap that surrounds the eye (or nearly so). The dark hindneck contrasts sharply with the white foreneck and throat, the latter being noticeable in flight. Compared to Common Loon, Pacific shows a neater, more crisply contrasting neck pattern, darker upperparts, and a duskier face. The oft-touted "chin-strap" is a good field mark when present, but some adults lack it, as do many first-year birds. Generally, winter Pacifics prefer more open ocean and relatively turbulent waters, though migrants may make use of calmer waters.
ARCTIC LOON: Very rare in North America, and very similar to Pacific Loon, it is heavier overall and has distinctive white flank patches in all plumages, though this character requires careful interpretation. Posture affects the prominence of the flank patch, so this character should be used in concert with other features. The white flanks are most obvious when a bird is at rest on the water, or swimming slowly. Then, depending on how much of the bird's flanks are visible above the water, you may see either a broad, arching swath of white along the sides, or only a small, restricted white patch just at the rear flanks. Flank pattern and head shape are less easily assessed on active or foraging loons. Any loon of any species that is bathing, preening, or rolling on its side may suddenly reveal white underparts that can be misinterpreted as white flank patches. Structurally, Arctic is intermediate between Pacific and Common loons but is closer to Pacific. Compared to Pacific, it is chunkier, with a thicker neck and a blockier and more angular head, usually with a prominent forehead bump. The bill is thick and even, larger and stouter than Pacific's, and is often held slightly uptilted (rarely so in Pacific). Separating the two species in flight is possible only with experience and great care, using overall structure and flank/rump pattern. Breeding: Compared to Pacific, Arctic shows a darker, more concolorous lead-gray head and nape, and a broad white flank patch. The vertical neck stripes are broader and bolder than on Pacific and also connect with those on the shoulders and chest-sides. In Alaska, Arctic Loons prefer sheltered bays rather than isolated tundra ponds and are rarely, if ever, found in the latter. Nonbreeding/Immatures: Again, similar to Pacific, these are clean cut, dark dorsally, and pale ventrally. The black and white on the neck sides contrast sharply, and the dark back contrasts with the white flank patch. The "chin-strap" present on some Pacific Loons is always lacking on Arctic, which also seems to prefer less open ocean waters and is more often found on sheltered bays; it may also make use of large lakes more than Pacific.
COMMON LOON: Our most widespread and familiar loon, it is also probably the most frequently misidentified, mainly by overeager birders who do not understand its seasonal and age-related variation. As with all loons, structure varies in appearance depending on behavior, angle, distance, and lighting, so prolonged study helps ensure accurate identification. Common Loon is bulky and heavy billed, and the head usually shows a prominent bump at the forecrown, lending it a blocky-headed look. It is most similar to Yellow-billed Loon in nonbreeding plumage, especially when reflected sunlight or glare off the silvery bill makes the bill appear paler. Common Loon overlaps frequently with Pacific and Red-throated loons but is the only expected species on inland lakes. Heavily built, in flight it shows large feet projecting behind the tail; it often flies higher than other loons and is regularly seen flying over land. Breeding: Familiar, distinctive, and beautiful, adults at this season show a black head and bill, and black upperparts that are heavily spotted white on the back. The underparts are white and the neck has white striping on the sides. This pattern is similar only to that of Yellow-billed, but the latter breeds only in the high Arctic, whereas Common breeds in more populated latitudes, on placid lakes across the northern United States and Canada. Nonbreeding/Immatures: Blackish, or gray brown above, these have a unique neck pattern with a triangular white "wedge" pointing backward, above a darker half collar that rests just above the neck base. Basically, this is a shadow of the breeding plumage pattern. A broken whitish eye ring makes the face appear whiter than on a Pacific or Arctic loon. The bill is usually gray or pale grayish blue, with a darker culmen and darker cutting edges. Juveniles and first-winters have broad whitish edges to the upperparts, and first-summers are generally like first-winters. Second-winters are adultlike but second-summers are highly variable, with some like second-winters, and others similar to breeding adults but usually with blotchy white patches on the neck and face.
YELLOW-BILLED LOON: This is the largest loon, with a thick neck and a heavy, pale yellowish bill in all ages. It is rarely seen, particularly away from the Pacific Northwest, where it is scarce or rare along the coast (from Alaska to Washington) in winter. But Yellow-billed Loons, especially first-winter birds, are increasingly being found as vagrants at inland lakes across the West. The big head usually shows an obvious peaked forecrown, and even at a good distance, a distinctive pale bill, which averages palest at the tip. The culmen is straight, but the mandible is slightly recurved, producing an uptilted look. The bill is straw yellow during breeding, but yellowish white otherwise, sometimes appearing gray based (especially on first-winters). In flight Yellow-billed is most similar to Common Loon, being heavily built and generally flying higher than other species. It's best distinguished from flying Commons by the head and bill patterns. Breeding: Similar to Common, but they have broader white neck stripes (widest in the middle) and larger white back spots. Nonbreeding/Immatures: Paler overall than Common, Yellow-billed has a notably paler head and neck, often showing a distinct, darkish auricular spot. The darker areas of the head and upperparts are usually grayish or more sandy brown than on Common Loon. Especially problematic are first-summer Common Loons with pale bills. While Common Loons can have very pale silvery bills, note the differences in bill shape and general carriage. Common Loon usually shows an evenly pale bill, whereas Yellow-billed is typically paler on the tip.
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Excerpted from Better Birding by George L. Armistead, Brian L. Sullivan. Copyright © 2016 Princeton University Press. Excerpted by permission of PRINCETON UNIVERSITY PRESS.
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