IN THE SCOPE NO.50 Spotted and Solitary sandpipers and a review of this column’s history

TONY LEUKERING

By my count, this issue of Colorado Birds sees the 50th installment of the In The Scope column, with the first column published in January 2007 (Leukering 2007). While the Colorado Field Ornithologists delays putting these columns on the website for about a year after hard-copy publication, all but the most-recent essays are available there (www.tinyurl. com/InTheScope). In The Scope began when Nathan Pieplow, the at-the-time brand-new editor of the journal, requested my thoughts on a column that would have the back cover as its venue, an idea borrowed from Western Birds. In our phone conversation, we quickly came to an agreement on an ID-based column with Colorado’s avifauna as its subjects. While I don’t know if Nathan thought that the column would have this kind of longevity, I have to say that I am surprised by it. I owe Nathan many thanks, and I also want to thank my various co-authors and, particularly, those authoring essays without my meddling (making my life a bit easier). Nathan penned the first ITS column that lacked my name as an author, writing a bang-up piece on vocalizations of three of the “Types” of Red Crossbill (essay #3). Steve Mlodinow wrote the 23rd (on Herring x Glaucous-winged Gull hybrids), 30th (on Colorado’s White-breasted Nuthatches), and 42nd (Tundra vs. Trumpeter swans) installments in his erudite and inimitable fashion.

186 Colorado Birds | Fall 2019 | Vol. 53 No. 4 Colorado Birds | Fall 2019 | Vol. 53 No. 4 187 IN THE SCOPE

Solitary Sandpiper and Spotted Sandpiper, Jefferson. 31 August 2018. Photo by Rob Raker.

Nick Moore did a great job on the 40th essay, covering the Colorado-occurring subspecies of Brown Creeper (a species that might be split in the future). Nathan was also a co-author with me of the 11th, 13th, 16th, and 32nd installments, while Steve helped me out – or, rather, I helped Steve out, with the 24th, 26th, 43rd, and 46th essays. Of the previous 49 ITS essays, 26 have treated, more or less, species-level identifications that cause birders field-ID angst. Some of these dealt with only a subset of the species (e.g., female Eurasian Wigeon, juvenile Horned Lark, odd male Brown-capped Rosy-Finches). Note that the treatment of dabbling-duck soft-parts coloration was dealt with in two installments, a quiz (the 33rd) and its solution (the 34th). Twelve previous columns treated subspecies, either of an individual species (e.g., Marsh Wren), of two species (Downy and Hairy Woodpeckers), or Colorado subspecies in a general fashion. This focus is not at all surprising, given that Colorado is a meeting place of multiple major biomes. Four columns pointed out the identification difficulty created by hybrids (e.g., dark ibises and Yellow- rumped Warblers). Other columns treated terminology, the usefulness of seasonal timing in field identification, and other topics in which field identification was an important aspect. Many essays dealt with multiple of these aspects of identification, so it is not so easy to put numbers to each category independent of others, add them all up, and come up with 49.

Colorado Birds | Fall 2019 | Vol. 53 No. 4 187 IN THE SCOPE

Spotted Sandpiper, Jefferson. 22 May 2019. Photo by Rob Raker.

THE PROBLEM OF UNSPOTTED SPOTTED SANDPIPERS

Once July begins (or, even, somewhat earlier), many of Colorado’s birders begin searching for fall-migrant shorebirds. While the West Slope and the montane areas of the state get short shrift in the way of shorebird migration, Colorado’s eastern plains often provide a bonanza, once enough water is pulled from the various large reservoirs to irrigate crops to create extensive mud flats. However, birders in all parts of the state have to deal with the shorebird-identification difficulty engendered by unspotted Spotted Sandpipers. As I regularly review photos submitted to eBird in support of identifications, I have found that a surprising number of the photos submitted as depicting Solitary Sandpipers are actually of Spotted Sandpipers, not just from Colorado, but from throughout the regular range of Spotted Sandpiper (eBird 2019). I feel it is past time to treat this topic in this venue. Since exceedingly few would mistake an alternate-plumaged Spotted Sandpiper – you know, the plumage with all those black spots below – for a Solitary Sandpiper, this identification pothole is restricted to Spotted Sandpipers in plumages other than alternate. SPOTTED SANDPIPER PLUMAGES

Do not worry, this section is short and straightforward, not needing to delve into mind- numbing plumage detail. While there can be age-related minor differences within basic and alternate plumages in Spotted Sandpipers, there are only three general varieties of appearance in the species. [For more details on molt and plumages, see Leukering (2010a) and references therein]. Spotted Sandpipers in alternate plumage have those distinctive underparts with numerous large, black spots or blotches. Because of that distinctiveness, I feel that many birders do not really study the species and learn the smaller details of plumage that would assist in identifying the species when dressed in a plumage other than alternate. Yes, observers pick up on the odd, stiff, rapid wingbeats of the species in short, local flights and on the habitual rear-end bobbing, but not the plumage details. Unfortunately, the wingbeat of Spotted Sandpipers is much different in long-distance traveling flight and individuals do not always perform the deep, rear-end bobbing that is so distinctive. The appearance of adult Spotted Sandpipers in basic plumage is like that of alternate, though with some subtractions and additions.

188 Colorado Birds | Fall 2019 | Vol. 53 No. 4 Colorado Birds | Fall 2019 | Vol. 53 No. 4 189 IN THE SCOPE

Solitary Sandpiper, Jefferson. 31 August 2018. Photo by Rob Raker. Solitary Sandpipers’ In basic plumage, they either lack underparts spotting terrestrial bobbing entirely, or it is greatly reduced. They also lose much of the white supercilium that helps to define the blackish eyeline motion is understated in alternate plumage. The primary addition is of gray-brown compared to that of feathering of variable extent on the chest and upper sides. At Spotted Sandpipers the more-extensive end of this variation, the chests of Spotted Sandpipers can somewhat mimic the appearance of that of Solitary Sandpipers. With Solitary Sandpiper also having a bobbing aspect to its terrestrial motion, albeit understated compared with that of Spotted, one can see why birders might confuse the two. Finally, juveniles appear much like adults in basic plumage, but with an important difference, one that is very helpful in differentiating such birds from Solitary Sandpipers: the black bars on the upperparts’ feathers of juvenile Spotted Sandpipers are very obvious, much more so than is typical on adults. The wing coverts have obvious straight or somewhat wavy black bars (Figure 1, back cover; red arrow), while each scapular has a subterminal black band that follows the curve of the feather tip (Figure 1, back cover; green arrow). Unfortunately, juveniles, more so than even basic-plumaged adults, have the dark eyeline much less distinct, creating less contrast with the broken eye rings, often making those breaks difficult to discern at even fairly close range. This diminution of the contrast of the dark eyeline makes looking for the dark bars on the upperparts’ feathers on Spotted Sandpipers even more important. Remember: If there are obvious, contrastingly dark bars on scapulars and/or wing coverts, then Solitary Sandpiper is ruled out. Other plumage and structure features that can assist in differentiating Spotted Sandpipers from Solitary Sandpipers are presented below, in rough order of ease of use/importance. Overall Coloration: Spotted Sandpiper is a “shorebird-colored” shorebird; that is, brown above, pale below, not all that different from many another shorebird species. Solitary Sandpiper is very dark above – notably darker than either yellowlegs species and any other Colorado shorebird species with which it might be confused. Those very dark upperparts and wings contrast very strongly with the pale underparts, much more so than do the brown upperparts of Spotted. Solitary also has very dark undersides to the wings, again creating strong and abrupt contrast with the pale underparts, unlike on either yellowlegs or Spotted Sandpipers, all of which have mostly pale undersides to the wings.

Colorado Birds | Fall 2019 | Vol. 53 No. 4 189 IN THE SCOPE

Behavior upon landing: Like other species of the genus Tringa, Solitary Sandpipers raise their wings vertically over their bodies upon landing – almost as if stretching – before then folding them, a behavior not typical of Spotted Sandpipers. Upper-side bar: Except when obscured by posture or the vagaries of how the plumage is held, Spotted Sandpiper shows an obvious and well-demarcated intrusion of bright white from the underparts that separates the gray-brown plumage of the chest from the dark wing (See Figure 1, back cover; black arrow). Solitary Sandpiper often shows a vague, paler area there, though occasionally exhibits a more-distinct pale intrusion. Back-end relationships: No, this is nothing sordid, it refers to the juxtapositions of tertials, wing tips, and tail tip. On the back-cover photos (Figures 1 and 2, back cover), the longest tertial is indicated by a white arrow, the wing tip by a blue arrow. The tips of, respectively, the longest tertial, longest primary, and tail are indicated by white bars, blue bars, and red bars in Figures 1 and 2 (back cover). Spotted Sandpiper is a fairly short-winged and long-tailed shorebird, while Solitary is a fairly long-winged shorebird with an “average”- length tail. Thus, where the wing tips fall relative to the tail tip on a standing bird will typically show distinct differences that can cinch an accurate identification. First, in most Spotted Sandpipers, the tail extends beyond, often well beyond, the tips of the wings, whereas Solitary’s wing tips reach or surpass the tail tip. Second, the primary tips of Spotted Sandpipers barely protrude beyond the tip of the longest tertial – that relationship is known as primary projection, while Solitary’s longest primaries extend well beyond the tips of the tertials and often extend beyond the tail tip. This difference in primary projection is very useful in quickly ruling either in or out, as it is in differentiating larks from pipits (Leukering 2009). Again, see Figures 1 and 2 on the back cover. Leg shape: Spotted Sandpiper is a dumpy species, with relatively short, thick legs. They are so short that most of the leg length above the ankle (technically, the tarso-metatarsal joint; though thought of as the “knee” by many, the actual “knee” is hidden by the plumage in virtually all birds) is hidden by plumage. Solitary shows much more leg above that joint and the legs are thinner than those of Spotted. Leg length makes for noticeable differences between the two species in how they walk. I encourage observers to really watch Spotted Sandpipers in order to pick up on the odd, shuffling gait of the species, which is somewhat reminiscent of the creeping gait of Least Sandpiper, not the somewhat elegant striding of Solitary. Face: Spotted Sandpiper has a fairly pale face that is usually highlighted by a strong, dark eyeline that bisects a whitish eye ring. Juvenile Spotted Sandpipers usually have a less- obvious version of the eyeline, and it might break the eye ring only on the front or back edges. Solitary Sandpiper, however, always shows a complete eye ring, unlike the broken eye ring of Spotted. Solitary’s eye ring is often, particularly in fall, connected to a wide supraloral bar of white, creating a spectacled look very much like that of Swainson’s Thrush. Solitary Sandpiper does exhibit a dark eyeline, but it is usually fairly vague and often absent or nebulous behind the eye. Regardless, it is always greatly dominated by the eye ring. Though a close look at Spotted should always reveal that its eye ring is broken, views from farther away, particularly of juveniles, can give an incorrect impression of a complete eye ring; note how indistinct the breaks are on the bird in Figure 1 (back cover). Spotted also shows a wide, pale supraloral bar, but it is typically much duller than the eye arcs. In summary, the eye ring of Spotted Sandpiper does not typically dominate the face, at least, not to the extreme as on Solitary Sandpiper. Bill: Spotted Sandpiper has a deeper-based bill than does Solitary, with that deep base imparting a more-triangular shape to the bill, as compared to the slightly thinner bill of Solitary, a bill that can often appear to droop ever so slightly at the tip. See Leukering (2010b) for additional information about Solitary Sandpiper plumages.

190 Colorado Birds | Fall 2019 | Vol. 53 No. 4 Colorado Birds | Fall 2019 | Vol. 53 No. 4 191 IN THE SCOPE

ACKNOWLEDGMENTS

I greatly appreciate the reviews of an earlier draft of this essay by Cameron Cox and Steve Mlodinow; their expertise made this a better, cleaner essay. LITERATURE CITED eBird. 2019. eBird: An online database of bird distribution and abundance [web application]. eBird, Ithaca, New York. Available: http://www.ebird.org. (Accessed: 30 April 2019). Leukering, T. 2007. Gray-cheeked Thrush. Colorado Birds 41:59-62. https://cobirds.org/ CFO/ColoradoBirds/InTheScope/37.pdf Leukering, T. 2009. Juvenile Horned Lark. Colorado Birds 43:152-154. https://cobirds.org/ CFO/ColoradoBirds/InTheScope/28.pdf Leukering, T. 2010a. Molt and plumage: A primer. Colorado Birds 44:135-142. https:// cobirds.org/CFO/ColoradoBirds/InTheScope/24.pdf Leukering, T. 2010b. Identifying Solitary Sandpiper subspecies: Why and how. Colorado Birds 44:203-206. https://cobirds.org/CFO/ColoradoBirds/InTheScope/23.pdf AUTHOR Tony Leukering, PO Box 52, Wiley, CO 81092 ([email protected])

Figure 1 (Back Cover). This juvenile Spotted Sandpiper illustrates the typical contrasting dark bars on the scapulars (green arrow) and wing coverts (red arrow) of the species. Adult Spotted Sandpipers also show these bars, though they are less obvious, as they are not highlighted by pale bars as on juveniles. Contrasting dark bars on the upperparts rule out Solitary Sandpiper. The orange arrow points out the obvious dark line – the eyeline – extending from the bill through the eye and extending to the nape. The black arrow illustrates the protrusion of white from the underparts that separates the dark coloration on the chest from the dark wings. The white arrow points out the longest tertial, the tip of which is indicated by the white bar. The blue arrow points to the outer primaries and the blue bar indicates where the tip of the longest primary – the wing tip – ends. The red bar indicates the tail tip. Liberty State Park, Hudson County, New Jersey. Photo taken 19 August 2018 by Shayna Marchese.

Figure 2 (Back Cover). This juvenile Solitary Sandpiper shows the contrasting pale spotting on the scapulars (green arrow) and wing coverts (red arrow). The bird’s white eye ring dominates an otherwise plain face, with this individual showing only a bare suggestion of a darker eyeline. Solitary Sandpiper generally completely lacks Spotted Sandpiper's white protrusion between the dark chest and the wings, though can show a suggestion of it (black arrow). This species shows long primary projection: the distance between the tip of the longest tertial (white bar) and the tip of the longest primary (blue bar). The primaries of Solitary Sandpiper typically extend beyond the tail tip (red bar), though shorter-winged individuals may have the tips of the wings and the tail in the same place. Compare the juxtapositions of the white, red, and blue bars in these back-cover figures. Pacific Grove, Monterey County, California. Photo taken 21 August 2015 by Carole Rose.

Colorado Birds | Fall 2019 | Vol. 53 No. 4 191

Figure 1

Figure 2

IN THE SCOPE ...... Page 186

194 Colorado Birds | Fall 2019 | Vol. 53 No. 4 Colorado Birds | Fall 2019 | Vol. 53 No. 4 194