IN THE SCOPE

Distinguishing Greater and

TONY LEUKERING

Greater ( melanoleuca) and Lesser (T. flavipes) yellowlegs are similar species that breed in the extensive forest of Canada and U. S. and spend winters, primarily, at subtropical and tropical latitudes. , being larger and thus hardier, winters farther north and in larger numbers in the temperate zone than does Lesser Yellowlegs. Most birders find distinguishing the two species simple and easy… when they’re standing next to each other (Figure 1, back cover). In that situation, the Greater vs. Lesser thing works very well. Single yellowlegs or multiple yellowlegs of the same size, however, have given birders fits since… well, since there have been birders. One hoary proverb about this identification problem that’s been making the rounds for longer than I’ve been birding works amazingly well, given reasonable views. The proverb involves mentally projecting the bill of a mystery yellowlegs as originating at the front of the head but projecting through the head to the rear. The hoary part had one mentally hammering the bill back through the head, but we live in a different time. After the imagination task, however one gets the bill to go in the opposite direction, the difference between the two species is that the bill of a Greater would extend well beyond the back of the head, while that of a Lesser, if it extended beyond the head at all, would do so only marginally (Figure 2, back cover). Unfortunately, that feature is impossible to use if the is asleep with its head tucked. It is also difficult to use when the bird is very active, and both yellowlegs species can be very active foragers. The solution to the Greater vs. Lesser problem is the same as for virtually all identification quandaries: assess more features. As I have mentioned more than once in this venue, single-feature identifications are fraught with, if not peril, a high chance of being incorrect. Unfortunately, the various plumages of one yellowlegs species are closely matched by those of the other. Additionally, it is critical when using any plumage features to distinguish yellowlegs that one first assess which plumage the bird is wearing and whether it is in the process of changing plumages; one wants to compare apples to apples (say, definitive alternate plumage to definitive alternate plumage) and oranges to oranges (say, juvenile plumage to juvenile plumage). Thus, I describe in this essay the various yellowlegs plumages and their molt strategy as they relate to Colorado occurrence of the two species. I go on to discuss vocal, plumage, structural, behavioral, and migration- timing features that can greatly assist in correct identification of Greater and Lesser yellowlegs. Yellowlegs identifications are more certain the more of these features that one uses to arrive at an identification. However, I start with a simplified identification key that can quickly allow accurate identification of a large percentage of yellowlegs that are seen well.

QUICK-AND-DIRTY YELLOWLEGS IDENTIFICATION While scoping the shorebirds at your local pond or mudflat, you run across a taller, lankier with grayish plumage and long yellow legs. There are only 12 sandpiper species – that is, not plovers or any other sort of shorebird, like avocets – seen annually in Colorado whose legs are yellow, or which can be interpreted as yellow. Of these, Least, Pectoral, and Spotted do not have what anyone might term “long” legs. Additionally, Upland, Least, Buff- breasted, and Pectoral sandpipers do not exhibit a plumage that might be termed “gray.” These two features have eliminated half of our “yellow-legged” shorebird species. You look at the bird’s tertials. Do they have paler markings at all? If not, then the bird is not a yellowlegs, nor is it even in the genus of yellowlegs (Tringa). If so, are those markings white or creamy spots? That is, are those markings very pale individual markings that approximate

Colorado | Summer 2020 | Vol. 54 No. 3 119 IN THE SCOPE circular shape? That is, are they not bars or fringes of paler color? If the tertial markings on the bird in question are bars or fringes, then the bird is not a yellowlegs, nor is it even in the genus of yellowlegs. The answers to these questions can rule out three other yellow-legged shorebird species: Stilt Sandpiper and both species. You look at the bird’s upperparts. Are they very dark from crown to wing tips and with a strong brown aspect to the color? If so, your bird is probably a Solitary Sandpiper. Check the leg color. Is there a greenish aspect to it? If so, your bird is certainly a Solitary Sandpiper. How much leg is visible above the “knee” (actually the tarso-metatarsal joint, akin to our ankle)? If your answer is not very much, then your bird is certainly a Solitary Sandpiper. Once through the preliminaries and you have decided that your mystery sandpiper is, indeed, a yellowlegs, look at the bill. Is it easily much longer than the head is deep (from front to back)? If so, your bird is a Greater Yellowlegs and if definitely not, a Lesser Yellowlegs. If you are unsure, look at the base of the bill. Is it obviously paler than the terminal half of the bill? If so, your bird is a Greater Yellowlegs and if not, a Lesser Yellowlegs. Once through these two bill characters and you find yourself still unsure as to the bird’s identification, then read on, MacDuff, read on.

MIGRATION SPRING – Individual yellowlegs, particularly those wintering at tropical latitudes, initiate northward migration in late winter or very early spring. The individuals of either species to arrive first in Colorado in spring are nearly always Greaters, typically before the middle of March (Figure 3). Many of these earliest birds have not completed their molt into alternate plumage (see below). However, even adults are often still wearing a mix of alternate and basic scapulars and wing coverts on breeding grounds; that is, most do not replace all of the feathers that they might in the prealternate molt. The first Lesser Yellowlegs usually follow one to two weeks later, arriving before the end of March. Both species usually absent themselves from the state before June, though there have been laggards of both species present in the first two weeks of June: totals of 12 each in the first week, eight Greaters and three Lessers in the second week. Figure 3a illustrates well the earlier arrival of Greater Yellowlegs and the similar departure time of both species, while Figure 3b shows the much earlier abundance peak of Greater (1st week of April vs. 4th week of April). FALL – As with most migrant shorebird species, should a yellowlegs nesting attempt fail, even early in the cycle, the failed breeders typically initiate migration toward the winter grounds. Thus, the first southbound migrant yellowlegs, usually Greaters, arrive in Colorado about 22 June, less than a month after the departure of the last spring migrant. Unlike in spring, shortly after the first Lesser Yellowlegs have arrived in Colorado, the species quickly surpasses Greater Yellowlegs in both abundance (2nd week of July) and frequency of occurrence (3rd week of July). All yellowlegs in the state from late June through most of July are older birds (either one-year-olds or full adults) and most of those are non-breeders or failed breeders. Some successful breeders may arrive by mid-July, with most or all of these probably being adult females, because in high- latitude-breeding shorebird species, that sex often or usually abandons the brood to the male before the progeny can fly well (Ashkenazie and Safriel 1979, Elphick and Tibbits 2020, Tibbits and Moskoff 2020). The first juvenile yellowlegs arrive in Colorado in late July (S. G. Mlodinow in lit.) and can be readily discerned from older birds by their fresh, neat plumage (see below). As fall progresses, the adult: juvenile ratio changes to where juveniles comprise more than half the yellowlegs in the state by mid-August or so (pers. obs., S. G. Mlodinow in lit.). Very few Lessers remain in

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Colorado beyond October (Figure 3), while Greater Yellowlegs are often present, usually in small to tiny numbers, to the end of November. Most Greaters present after November are probably attempting to winter locally. In the sections on plumages, below, it is not critical to memorize what plumages and what molts are discussed, providing that one retains the understanding of how appearance typically changes through time. However, I strongly encourage learning about molts and plumages, as that understanding is something that most highly skilled birders have. For a quick overview, see Leukering (2010), but for a more-thorough understanding, I highly recommend reading Steve Howell’s book on the subject (2010). The treatment is engaging and highly accessible.

PLUMAGES In Colorado, both Greater and Lesser Yellowlegs occur predominately in two plumages: alternate plumage (Figure 4; either definitive alternate or first alternate; see Leukering 2010) and juvenile plumage (Figure 5), with, perhaps, various stages of transition out of those two plumages in fall. Late in fall, particularly after all or virtually all Lesser Yellowlegs have departed the state, Greater Yellowlegs can be found that are mostly or entirely wearing formative plumage (if the bird is an immature; see Leukering 2010, 2019) or definitive basic plumage (if an adult). These two plumages share many more similarities than differences, so I hereafter refer to the two plumages as “winter plumage” (Figure 6) Obviously, the tiny number of individual Greater Yellowlegs that spend the winter in the state wear winter plumage during that time; Colorado has no winter records of Lesser Yellowlegs. MOLT STRATEGY – As in other shorebird species (and nearly all other bird species having an alternate plumage), the two yellowlegs species initiate molt into alternate plumage (whether definitive alternate or first alternate) on winter grounds and complete it there or on migration to breeding grounds (Pyle 2008, Elphick and Tibbits 2020, Tibbits and Moskoff 2020). The definitive prebasic molt (the molt that adults conduct to replace alternate plumage with basic plumage) begins immediately after breeding with the replacement of some feathers in various feather tracts on the body, particularly the head, back, and chest and, at times, some scapulars. At this point, the strategies of Greater and Lesser yellowlegs diverge. Lesser Yellowlegs suspends the molt during migration and restarts it shortly before or after arriving at winter quarters. Some Greater Yellowlegs conduct much of this molt on migration at stopover sites (Pyle 2008). Thus, an adult yellowlegs in Colorado in extensive winter plumage or one that is in active wing molt is almost certainly a Greater Yellowlegs. Active wing molt can be discerned by the presence of symmetrical gaps among the primaries or secondaries in both wings and by secondaries or primaries that are obviously shorter than neighboring feathers on both sides of the short feather or feathers. Unfortunately for Colorado birders, the molt-strategy difference between the two species does not seem to hold away from coastal or other areas close to typical Greater Yellowlegs winter grounds. At least, I have seen no photographs of Greater Yellowlegs in Colorado in active wing molt. Of course, only a tiny percentage of the Greater Yellowlegs passing through the state get photographed, particularly photographed well enough to discern whether individual birds are molting. Since a tiny number of the species winters in the state, some must go through at least some of that molt here. So, though it is unlikely that any single yellowlegs that one encounters in Colorado is in active preformative or prebasic molt, those that are can probably be safely identified as Greaters. Juvenile yellowlegs, that is, those hatched from nests in summer, depart breeding grounds shortly after becoming independent. As with older birds, young-of-the-year Lesser Yellowlegs conduct no molting in Colorado, while the same age class of Greater Yellowlegs may replace extensive

Colorado Birds | Summer 2020 | Vol. 54 No. 3 121 IN THE SCOPE portions of juvenile plumage on fall migration (Pyle 2008), although there is little evidence of that in Colorado photos of the species. ALTERNATE PLUMAGE – In both species, this plumage has blackish streaking on the front of the neck, black barring on the sides and chest, and a highly variable number of white-fringed black scapulars and wing coverts. The variability in the number of alternate scapulars between birds is apparently due to multiple factors, including age (adult versus one-year-old), sex (Tibbits and Moskoff 2020), wintering latitude, and, probably, resources available on winter grounds. No other plumage in either species exhibits any of these features, though individuals in plumage transition in either direction can have a variable amount of such feathering. Despite the similarity of plumage in the two species, there are some useful differences. The most useful is that in alternate plumage, Greater typically shows long black bars on the sides, whereas these markings are usually restricted to chevrons on Lesser (Figure 4). JUVENILE PLUMAGE – When the first juveniles of the fall arrive, their plumage presents a striking contrast to the worn and mottled appearance of adults at the time (Figure 5). All of the scapulars and wing coverts are neatly fringed in buff (wearing to white). As in adults, a first-cycle yellowlegs in active molt in Colorado is almost certainly a Greater. WINTER PLUMAGE – These plumages, formative and definitive basic, are quite similar in the two species and comparatively dull in both species, exhibiting none of the black markings typical of alternate plumage and much less fringing on upperparts feathers typical of juvenile plumage (Figure 1, back cover). Older birds of both species can achieve winter plumage by the end of August, although, as noted above, Lesser Yellowlegs does not molt into winter plumage until reaching winter grounds and apparently few Greaters conduct any of this molt in Colorado. However, also as noted above, any Greater attempting to winter in the state has probably undergone at least some of this molt in Colorado.

BILL AND LEGS As mentioned in the introduction, bill length is, perhaps, the single visible feature of yellowlegs that most readily enables quick identification. If the bill is obviously longer than the head is deep (front to back), the bird is a Greater Yellowlegs, while if it is only about equal to the depth of the head or only slightly longer, the bird is a Lesser Yellowlegs. Another useful bill feature is, indirectly, the nostrils. While the placement of the nostrils on the bill is different in the two species, with Lesser’s nostrils closer to the base of the bill than those of Greater, that difference can be hard to assess. However, because the base of the bill of Greater is paler (with as much as the basal half of the bill being pale), often obviously so, the nostrils stand out better against that pale part of the bill than against the virtually unrelieved black of the bill of Lesser. This means that if the nostrils are readily visible – given reasonable views at relatively short distance, the bird is probably a Greater, and if not, a Lesser. Given experience, a yellowlegs’ leg width and the “knobbiness” of what many birders see as the “knees” – although they are actually equivalent to our ankles – can be useful identification features. Greater Yellowlegs has thicker legs and wider tarso-metatarsal joints (the “ankles) that are typically obviously wider than the width of the main parts of the legs. On Lesser, even with their skinnier legs, the tarso-metatarsal joints are only barely wider than the width of the main parts of the legs.

BEHAVIOR Unlike the typically probing, tactile-foraging sandpiper species of the genus , the two yellowlegs (and other members of Tringa) are visual predators, finding individual prey items

122 Colorado Birds | Summer 2020 | Vol. 54 No.3 Colorado Birds | Summer 2020 | Vol. 54 No. 3 123 IN THE SCOPE with their eyes and then endeavoring to catch them. Given that some of those prey are quite mobile, yellowlegs can often be found chasing them. While resting, both yellowlegs species can be found in relatively tight masses with each other and with many other species of shorebirds. If relevant species are present, resting Greaters tend to gravitate to the larger shorebird species, such as , , and . Lessers seem to be less picky, though it can be harder to pick individuals of that smaller species out of masses of large shorebirds. Greater Yellowlegs is not a strongly social species, being generally found in smaller, less-cohesive flocks on the ground and in the air. While foraging, Greater Yellowlegs often use deeper water than does Lesser and the less-social aspect of Greater Yellowlegs and apparent interest in maintaining social distance from other Greaters imparts a quieter, less-bickering aspect to the species’ foraging. Greaters often dash about through water in a frenetic manner after highly mobile prey, such as small fish, somewhat recalling a giant Wilson’s . In flight, individual Greater Yellowlegs in flocks maintain multiple body-lengths distance from conspecifics, giving those flocks an open look (Figure 7) that is somewhat loon-like (Behrens and Cox 2013). Lesser Yellowlegs is strongly social, often found in larger, tighter flocks than is Greater Yellowlegs. At a site with many Lesser Yellowlegs, foraging is a noisy affair, with much bickering between neighboring individuals that are often much closer to each other than Greaters typically tolerate. In flight, Lesser Yellowlegs flocks are tighter, more cohesive than are Greater Yellowlegs flocks (Figure 8), though not in the tight, wheeling flocks of manyCalidris sandpipers.

VOICE The typical calls of the two yellowlegs species, while similar, are usually readily distinguished with practice. While many observers may use the number of notes in a call bout as an identification feature, that can lead to error. Frequently. While Greater Yellowlegs often give three notes/bout and Lesser two/bout, each can give single call bouts of one to even six or seven notes. The more-identification-important aspect of yellowlegs calls is tone. Greater’s call are typically strident, often piercing (https://tinyurl.com/GRYEcalls, https://tinyurl.com/ GRYEcalls2), while those of Lesser are softer, rounder. In two-note bouts of Lesser Yellowlegs, the second note is often of lower pitch and less emphatic (https://tinyurl.com/LEYEcalls) while call bouts of Greater typically maintain pitch and intensity. Additionally, Lesser also gives a twittery call, as in the above-cited recording. In agonistic situations, Lessers will monotonously repeat a single note (https://tinyurl.com/LEYEcalls2).

PLUMAGE-STRUCTURE FEATURES: MORE CAREFUL STUDY REQUIRED If one finds oneself with some time at hand and happens to be ogling shorebirds, of which quite a few happen to be yellowlegs, one might look at the yellowlegs’ wing tips. Those wing tips hold identification clues but are variable enough to be unreliable without great care in their use. This section may be of interest to those students of bird identification that can readily find wing tips and tertials and tail on a standing yellowlegs and that enjoy a challenge. The outer primaries (the feathers forming the wing tip) on yellowlegs are dark and unmarked. On the folded wing, each wing tip forms an acute triangle of dark at the end of the body that contrasts with the dark-marked white tail and the white-marked gray tertials. Relative to overall size, Lesser Yellowlegs has longer wings than does Greater, as can be expected by the species’ longer average migration distance. This longer wing is expressed visually by the wing tips extending notably beyond the tail tip (a feature termed “wing-tip projection”), while the wing tips of Greater, if they extend beyond the tail tip, typically do so only marginally. Individual variation in both species provide for, if not overlap in wing-tip projection, nearly so. However, a yellowlegs with full-length outermost primaries that only barely reach beyond the tail tip can comfortably be

Colorado Birds | Summer 2020 | Vol. 54 No. 3 123 IN THE SCOPE identified as a Greater; those yellowlegs expressing the very long extreme of wing-tip projection are almost certainly Lessers. Another feature of interest that varies between the two species is the length of the longest tertial relative to the tail, with Greater having longer tertials than those of Lesser. That is, the longest tertial on Greater Yellowlegs extends farther rearward, creating a shorter gap between that tertial’s tip and the tip of the tail, than the longer gap of Lesser amplified by its shorter tertials. Unfortunately, this feature seems to be age-related, with juveniles of both species having shorter tertials (C. Cox in lit.). If one considers only adult yellowlegs, the result of Lesser’s longer wings (thus, longer primary projection) combined with its shorter tertials means that they typically show a much longer expanse of dark, unmarked wing tip than does Greater. This difference in expanse of wing tip visible beyond the tertials can be assessed quickly, with very long expanses pointing to Lesser and short ones to Greater. However, Greater Yellowlegs missing the longest tertial, either through molt or adventitious loss, can present the long-primaried look of Lesser (Figure 9). ACKNOWLEDGMENTS

I greatly appreciate the review of a draft of this essay by Cameron Cox. LITERATURE CITED

Ashkenazie, S. and U. N. Safriel. 1979. Breeding cycle and behavior of the Semipalmated Sandpiper at Barrow, Alaska. Auk 96:56-67. https://sora.unm.edu/sites/default/files/journals/ auk/v096n01/p0056-p0067.pdf Behrens, K. and C. Cox. 2013. Peterson Reference Guide to Seawatching: Eastern Waterbirds in Flight. Houghton Mifflin Harcourt, Boston. Elphick, C. S. and T. L. Tibbits. 2020. Greater Yellowlegs (Tringa melanoleuca), v1.0. In Birds of the World (A. F. Poole and F. B. Gill, Eds.) Cornell Lab of Ornithology, Ithaca, NY. Howell, S. N. G. 2010. Molt in North American Birds. Houghton Mifflin Harcourt, New York. Leukering, T. 2010. Molt and plumage: A primer. Colorado Birds 44:135-142. https://cobirds. org/Publications/InTheScope.aspx Leukering, T. 2019. Non-adult plumages: Terminology matters. Colorado Birds 52/53:23-29. https://cobirds.org/Publications/InTheScope.aspx Pyle, P. 2008. Identification Guide to North American Birds, Part II: Anatidae to Alcidae. Slate Creek Press, Point Reyes Station, CA, USA. Tibbits, T. L. and W. Moskoff. 2020. Lesser Yellowlegs Tringa( flavipes), v1.0. In Birds of the World (A. F. Poole and F. B. Gill, Eds.) Cornell Lab of Ornithology, Ithaca, NY. AUTHOR

Tony Leukering 2602 Avenue D, Scottsbluff, NE 69361 ([email protected])

124 Colorado Birds | Summer 2020 | Vol. 54 No.3 Colorado Birds | Summer 2020 | Vol. 54 No. 3 125 IN THE SCOPE Figure 3 (see description below)

Figure 1 (Back Cover). Distinguishing Greater Yellowlegs from Lesser Yellowlegs, and vice-versa, is quite easy… when they are standing next to each other, as Greater (back, right) is considerably larger than is Lesser (front, left). Reeds Beach, Cape May County, New Jersey; 1 January 2013. Photo by Tom Reed.

Figure 2 (Back Cover). Relative bill length is, perhaps, the single easiest and most-certain feature allowing identification of an unknown yellowlegs, though beware of confusing Solitary Sandpiper for Lesser Yellowlegs. The bill of Greater Yellowlegs (left) is noticeably longer than the head is deep, as much as 1.5x that of head depth. The bill of Lesser Yellowlegs (right) is the same length or only marginally longer than the head depth. Note that despite the abnormally pale base to this Lesser’s bill, the bill length is typical of the species. Alternate-plumaged Greater Yellowlegs, Forsyth National Wildlife Refuge, Atlantic County, New Jersey; 28 March 2018. Photo by Sam Galick. Juvenile Lesser Yellowlegs, Sanford, York County, Maine; 28 August 2017. Photo by Jeannette Lovitch.

Figure 3. Frequency of occurrence (a) and relative abundance (b) on eBird checklists of Greater Yel- lowlegs (blue) and Lesser Yellowlegs (pink) in Colorado. There are 48 eBird weeks, with weeks begin- ning on the 1st, 8th, 15th, and 22nd of each month. Frequency is the percentage of all eBird checklists in the specified date range and region on which the species was recorded. Abundance is the average number of birds reported on all checklists within a specified date range and region. The abundance metric includes checklists that did not report the species and provides a measure of how commonly a species is reported relative to other species in the region. Because abundance values are so low at times in which the species is quite rare, the values are essentially zero. This explains why, for example, the right tail on the Lesser Yellowlegs fall abundance curve hits the zero line earlier in the season than it does on the frequency graph. Image provided by eBird (www..org) and created 4 April 2020.

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Figure 4. Alternate plumage in both Greater (top) and Lesser (bottom) yellowlegs is indicated by chev- rons or barring on the sides and, in nearly all individuals, a variety of fresh, new, black alternate feath- ers with white spots and old, worn brown feathers with whitish spots. Both individuals here sport such a variety of feather coats because the prealternate molt is exceedingly individually variable in extent. Very few manage to replace even most of the upperparts feathers in the prealternate molt, much less all of them. Greater Yellowlegs, Forsyth National Wildlife Refuge, Atlantic County, New Jer- sey; 28 March 2018. Photo by Sam Galick. Lesser Yellowlegs, Tierra del Sol, Aruba; 16 April 2013. Photo by Steve Mlodinow.

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Figure 5 . Juvenile plumage in both Greater (top) and Lesser (bottom) yellowlegs, particularly early in fall, is very fresh and comprised of feathers all of the same generation. The sides lack barring or chevrons, the upperparts feathers are all neatly spotted with white, and the neck is more (Greater) or less (Lesser) streaked with darker coloration. Greater Yellowlegs, Cape May County, New Jersey; 6 September 2014. Photo by Sam Galick. Lesser Yellowlegs, Cape May Point, Cape May County, New Jersey; 11 September 2008. Photo by Steve Mlodinow.

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Figure 6. This Greater Yellowlegs is nearly entirely in basic plumage (aka winter plumage). The pale base to the bill (A) typical of Greater Yellowlegs is obvious on this individual. The blacker feathers among the wing coverts (B) are remnants of alternate plumage, which the bird will shortly replace. The outermost primaries (C) are old and faded and contrast strongly with the darker newly replaced pri- maries visible proximally (toward the body). Like the remnant alternate wing coverts, these outermost primaries will soon be replaced. Cape May Point, Cape May County, New Jersey; 11 September 2008. Photo by Tony Leukering.

Figure 7. This flock of Greater Yellowlegs shows the openness typical of flocks of the species, which tends to maintain social distancing more distinctly than does Lesser Yellowlegs. The Long-billed Dow- itcher in the right part of the flock provides an identification bonus. Because Greater Yellowlegs are larger than , the size comparison makes identifying the yellowlegs as Greaters absolutely certain; Lesser Yellowlegs are smaller than dowitchers. Humboldt County, California; 21 October 2019. Photo by Alex Lamoreaux.

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Figure 8. This flock of yellowlegs exhibits the typically tighter organization of Lesser Yellowlegs. Care- ful scrutiny of yellowlegs as they fly by or over may enable detection of the longer, narrower wings of Lesser as compared to Greater. Both width and length aspects of wing shape are acted upon by evolution, as relative to body size, longer, narrower wings are more efficient in long-distance flight than are shorter and/or wider wings. Lesser Yellowlegs has, on average, longer migration distances than do Greater Yellowlegs. La Alta Gracia Province, Dominican Republic; 8 January 2019. Photo by Jay McGowan.

Figure 9. Missing or disarrayed tertials can give a yellowlegs (or any bird) an odd appearance, and that is true of this photo’s subject. The white patch at the rear end of this Greater Yellowlegs (indicated by the arrow) is the rump/upper-tail coverts area that is visible only because the bird’s longest tertial is missing (presumably dropped during its prealternate molt). The missing tertial gives the bird a very long-winged look due to the extensive length of outer primaries that is exposed by that missing tertial. Merced National Wildlife Refuge, Merced County, California; 6 March 2020. Photo by Carole Rose.

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