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Life is what happens to you while you're busy making other plans." (John Lennon)
November 9, 2013, which seemed destined to embody "Murphy's Law," for me and nearly 40 0ther birders, ended up being a day that none of us and no birder fortunate enough to be at the 2013 Rio Grande Valley Birding Festival will ever forget.
Festival organizers, determined to make this year's festival–the 20th anniversary edition–an event worthy of the occasion, assembled a cast of birding luminaries and local birding legends to headline the celebration. While it might be hard to imagine the collective star power of David Sibley, Kenn Kaufman, Jon Dunn, Victor Emanuel and Father Tom Pincelli being upstaged by a single bird, they and seemingly everything else were pushed off of the front page by the discovery of the U.S.'s second Amazon Kingfisher on the penultimate day of the festival. A surprising array of rarities had already highlighted the week, including a pre-festival Fork-tailed Flycatcher near Brownsville and the continuing presence of a Golden-crowned Warbler, two Painted Redstarts, and a Tropical Parula, but those paled when compared to this find.
Jeff Bouton, the Leica Sport Optics Marketing Manager for the U.S, became an instant festival celebrity when he found the bird shortly after 7:00AM on Saturday morning. He notified festival field trip coordinator Mary Gustafson, who quickly spread the news among leaders of field trips scattered up and down Lower Rio Grande Valley. Over the next eleven hours all roads between Salineño and Brownsville led to a stretch of Texas Hwy 100 just southeast of San Benito. For some the bird was a drive-up, while others waited up to two and half hours to get a glimpse. Father Tom prevailed upon the Cameron County Sheriff (one of his parishioners) to send out a couple of squad cars to direct traffic and ensure the safety of the hundreds of birders who would converge on the scene.
Each and every festival leader and participant could probably share a personal story about learning of this bird and the ensuing chase to see such a mega rarity. Field trips were abandoned. Vendor booths went unmanned. Festival staff took turns making the 20-minute sprint, while their anxious fellow volunteers impatiently awaited their turn to go see the bird. Birding is simultaneously a personal and social experience, thus the combination of seeing a life bird and doing so with others who share your passion invariably creates indelible memories. On this occasion Shawneen Finnegan, Victor Emanuel, Barry Lyon and I were leading a trip to South Padre Island. I had met Victor briefly at Estero Llano Grande State Park in early 2012 and reintroduced myself at the start of the festival. Barry and I had never met until the day before our trip. We were comparative strangers at the start of the day, but from this point forward the four of us will be linked by the shared joy of seeing this magnificent bird, showing it to others and the experiences described in the narrative below.
South Padre Island lies at the terminus of Hwy 100, about 25 miles east of where the kingfisher was found. Our day had gotten off to a rocky start, with the charter bus company scheduling one less bus and driver than what was needed for that day's festival outings. The staging for festival field trips is done in alphabetical order. On this day, South Padre Island was at the back of the queue...no bus for us.
Our field trip participants were remarkably tolerant of the snafu, in part because a large flock of Red-crowned Parrots decided to make their first stop out of the roost on a utility wire on the far side of the convention center parking lot. Having Victor as one of the leaders was fortuitous. After running his own international nature tour company for 30+ years, keeping the troops entertained comes to him as naturally as breathing. He shared all sorts of interesting natural history information about the Red-crowneds and other species of Amazona as we set up scopes and enjoyed prolonged views.
Nearly an hour after our scheduled departure time (6AM) a bus rolled up to the convention center. We boarded hastily while festival staffers loaded a jug of water and cups into the cargo bay. Our departure was then waylaid by another problem. They couldn't get the bay door to release and close. Our already harried driver Gilbert, who was driving this bus for the first time, frantically pushed control buttons in hopes that one of them would release the lock on the bay door. Finally, he hit the right one and the door fell closed. We were on our way shortly after 7AM. Ironically, our belated departure took us past the kingfisher site about the time it was being discovered. I remember seeing a couple of birders standing by the side of the road as we sped past, but they weren't familiar faces.
Since our trip was an hour late in getting started we were given the green light to extend it an extra hour (trips normally return by 1PM), which would put us back at the convention center around 2PM, well after the typical lunch hour. Festival president Danny Hoehne suggested that we find a place on the island to buy lunch for the group and assured us that the cost would be covered by the festival. Upon arriving at the our first birding stop–the South Padre Convention Center–Shawneen began making phone calls in hopes of finding a lunch option that wouldn't chew up too much birding time.
While Victor, Barry and I called out birds on the mudflat, she was on the phone. At some point I heard her calling my name and turned around to see her insistently waving for me to come over to where she was standing. The next words out of her mouth were, "Mary (Gustafson) just called, there's an Amazon Kingfisher back towards Harlingen." We gathered up the group and other leaders and I told them, "We have a rare bird emergency." The four leaders huddled up and considered our options. Did we want to continue with the trip and try to stop on the way back to the convention center, or would it be more prudent to go right away and see if we could salvage the rest of the trip later? It was sort of a no-brainer and no one expressed discontent when we announced that we would be getting back on the bus after just 15 minutes of birding on South Padre.
Being much closer to the kingfisher than most of the soon-to-be-abandoned field trips, ours was the first bus or van load of birders to reach the site. Surely this was some sort of cosmic payback for all the obstacles that the day had thus far presented. As we rolled up on the resaca and slowed to park on the north side of the road, we spotted a group of about 15 birders on the south side with optics raised. It was clear that they were on the bird and I think all four leaders simultaneously called out "they're on it! We quickly located the kingfisher, which was teed up on a dead snag sticking out of the canal. Most on the bus were able to see the kingfisher before we came to a stop. With bins, scopes, and cameras in hand, nearly 40 of us bailed from the bus in record time. About the time we were all out of the bus, the bird flew across to a small section of the abandoned oxbow on our side of Hwy 100. We set up scopes, snapped photos, and wallowed in our good fortune.
As we savored the kingfisher over the next 25 minutes, car after car and other festival vans descended on the scene. It was clearly time to get our charges back on the bus and reduce the man swarm, at least temporarily. We drove back to South Padre, arriving about 40 minutes late for a scheduled boat tour on the Laguna Madre. Thankfully, our captain ("Noe") and the crew at Dolphin Docks in Port Isabel were able to accommodate our now hopelessly mangled itinerary.
We enjoyed a spectacular cruise around the lower Laguna, which featured awesome views of various gulls, terns, skimmers, shorebirds, and a reasonably close-up encounter with a Mangrove (Yellow) Warbler. Noe expertly maneuvered his craft to the backside of a channel marker for point-blank looks at a Peregrine Falcon, surely the best-ever views of a wild Peregrine for most on the boat. We returned to dock just after 12:30PM, disembarked, then made our way back across the Queen Isabella Bridge and onto the island, where a local Subway had 36 sets of pre-ordered sandwiches and chips waiting. Like the outcome of our day...the order was perfect!
During the ride back to Harlingen, each leader took a turn at the microphone sharing their thoughts about the experience and thanking our participants for being such good sports throughout. With the last turn at the mic I offered up the quote at the top of this page and then concluded with,
"Today, we were living!"
In juvenile plumage, Least and Pectoral Sandpipers are virtually carbon copies of one another in terms of plumage. In the absence of a comparison that provides meaningful size context, many birders struggle to tell these species apart. Generally speaking, I believe that the use of structure can only take you so far when identifying shorebirds, but for this species pair, one structural clue is not only extremely helpful, it is diagnostic on hatch-year birds seen away from the breeding grounds.
Least and Pectoral Sandpipers breed far to the north of where most North American birders live and do most of their shorebirding, so it's important to discuss what happens with these birds before they show up on the local mudflat. They hatch sometime in June or perhaps early July and remain on the breeding grounds until they grow their first complete set of feathers and become capable of flight and ultimately migration. This feather set is their juvenile (juvenal in some references) plumage. It will be retained, unaltered through the first 2-4 months of their life, during which time they will undertake their first southbound migration.
By the time they depart the breeding grounds on their first southbound journey, their flight feathers are fully developed, thus the comparative lengths of various feather sets is essentially static and predictable. Morphometric comparisons of feather sets–comparing the length of one set of feathers with another feather set–often provides tell-tale clues when it comes to sorting shorebirds with nearly identical plumages. In Britain and Europe, birders have long used this method for identifying the Old World warblers in the genus Phylloscopus.
Least Sandpipers are comparatively short-distance migrants that can be found wintering in at least small numbers as far north as the Mid-Atlantic states on the East Coast and north to Washington and perhaps southern British Columbia on the West Coast. A significant portion of their total population winters in Mexico and the southernmost United States, but some winter as far south as northern Brazil and northern Chile (O'Brien et al. 2006, Paulson 2005). Pectoral Sandpipers are extremely long-distance migrants. They vacate North America entirely during winter. They are rarely found away from South America during winter, with most birds wintering from southern Peru, Bolivia, and southern Brazil, south to central Chile and southern Argentina (O'Brien et al. 2006).
Among shorebirds, there tends to be a direct correlation between the distance a species migrates and its comparative wing length. When comparing Least and Pectoral Sandpipers, this holds true. Least Sandpipers have comparatively short primaries (outermost flight feathers), which at rest do not project beyond the tips of their longest tertials, the long innermost wing feathers that lay over the top of folded wings. On a feeding Least Sandpiper, the tips of the primaries are often completely hidden under the tertials.
By comparison, Pectoral Sandpipers have long primaries. On a feeding or resting Pectoral, the tips of multiple primaries, usually at least three, can be seen projecting beyond the tip of the longest tertials. The extent and number of primaries sticking out past the longest tertial is often referred to as "primary projection." Pectorals show significant primary projection, while Least Sandpipers show virtually none.
There are some secondary field marks that I look for on Pectorals. As noted in several of the captions above, the basal third of their bill is paler, ranging from brownish to more orangish or even yellowish at times. While some Leasts may show a very small amount of brown at the base of the lower mandible, in general they appear to have all-black bills and never show extensive paler coloration over the basal 0ne-third of their bill.
Secondly, while the streaking on the breast of a juvenile Least is quite variable, as a general rule they are most heavily streaked on the sides of the upper breast and the streaking thins out towards the middle. Additionally, the streaking doesn't form a strong bib across the breast, nor does it come to a widow's peak of sorts in the middle of the lower breast. Pectorals often look to have a bib with a slight widow's peak in the middle and the streaking ends abruptly across the lower breast.
Thirdly, Pectorals have sturdier, thicker legs that tend to be more yellow in juveniles, while juvenile Leasts tend to have dingier and greener legs. Leasts often bend their legs and squat as they feed, while Pectorals seem inclined to stand more straight-legged.
Finally, and this is a subtle mark, but to my eye Pectorals seem to look more plain faced with very little contrast between the auriculars and the rest of the lower face. This can make the eye look fairly large. Leasts seem a little darker in the face to me, with a more obvious auricular patch and a less conspicuous eye. The dark lores on a Least strike me as more noticeable and more connected to front of the eye, while the dark in the lores of a Pectoral is less conspicuous and often fades out a bit right in front of the eye.
Over time and with lots of study, the sum of the parts should allow you to more easily separate Leasts and Pectorals, even without a good size comparison. But, until you get there, look for the primary projection. This is a highly reliable field mark. Plumage wear and hue, bill color, leg color, and even posture can all vary from bird to bird, but the comparative lengths of the primaries and tertials are not variable and can be used to confidently tell these two species apart.
O'Brien, Michael, Richard Crossley, and Kevin Karlson. 2006. The Shorebird Guide. Houghton Mifflin Company, New York, NY.
Paulson, Dennis R. 2005. Shorebirds of North America: The Photographic Guide. Princeton University Press, Princeton, NJ.
When it comes to identifying small olive-green birds with wingbars and eye rings, birders are often left befuddled. Separating flycatchers, vireos, and kinglets can certainly be daunting. Distinctive feeding behaviors and upright perching postures usually yield enough clues for the average birder to differentiate Empidonax flycatchers from vireos and kinglets, as the latter two groups tend to be gleaners rather than flycatching for their prey. After that, many birders will encounter serious roadblocks. One of the most problematic species pairs is Hutton's Vireo and Ruby-crowned Kinglet.
Field guides will tell you that Hutton's Vireo has a larger, thicker bill than a kinglet and that its feet are bluish-gray. Conversely, Ruby-crowned Kinglets are described as having a smaller bill and more blackish legs with yellow feet. In the grand avifaunal scheme, either of these species might be described as having a small bill, thus bill size difference is more subjective than objective and is highly dependent on the observer's contextual baseline. Simply stated, if you don't have much experience with these birds, or you haven't confidently identified a Hutton's Vireo, you have no basis for comparison. As for foot and leg color, seeing these differences takes a fairly close-up view with good optics. Additionally, both species tend to be pretty active, moving in and out of the foliage and showing a preference for more shaded areas. Getting a good look at the leg and foot color will occur with about every tenth bird you see. So, how do you identify the other nine?
Over the years, I've found a couple things that I look for as I separate these two species. First, I think that bill color is far more useful than bill size. Hutton's Vireos have a paler, horn-colored bill, which is indeed thicker and larger overall than the bill of a Ruby-crowned Kinglet, while the kinglet's bill is all-black. Although a Hutton's Vireo's bill may look dark in some light conditions, I can't recall seeing one with a truly black bill.
Another thing that I look for is the contrast in the wing pattern. While both species have two white or off-white wing bars and dusky olive-green wings, I find that the wings of Hutton's Vireos are less glossy looking and show less contrast overall. While their primary, secondary, and tertial edges are paler yellow, yellow-green, and whitish (tertials only), the contrast in this aspect of their plumage is not as obvious as it is on Ruby-crowned Kinglet, which have brighter yellow whitish to yellow margins on the outer webs of the folded flight feathers. The folded wings and greater coverts of Hutton's seem to be fairly similar in color to the mantle and scapulars. Also, the tertials of Hutton's are dusky colored and less black looking than the tertials of a Ruby-crowned Kinglet.
To my eye, wingbars of a Ruby-crowned Kinglet contrast more with the rest of the wing. Until I started really studying photos in preparation for writing this piece, I didn't fully realize why. When I went online and looked at a bunch of Ruby-crowned Kinglet photos, I hadn't realized that the bases of the secondaries (the exposed flight feathers right below the lower wingbar) are black or nearly so. This field mark is mentioned in the National Geographic Guide and illustrated quite well in the Sibley Guides. I also noticed that inner webs of greater coverts, the whitish tips of which create the lower wingbar, are also black, thus darker than the rest of the upperparts. These features, particularly the black base to the secondaries can be seen well in the in-hand spread wing shots of Ruby-crowned Kinglets at this link: http://www.powdermillarc.org/highlights/2009/latefall.aspx (you'll need to scroll down once you reach the page). I also noticed that the tertials (the inner most folded flight feathers) are near black with crisp white margins on Ruby-crowned Kinglets.
When I compared the features described in the paragraph above to the same aspects of a Hutton's Vireo's plumage, I noted that neither the greater coverts nor the base of the secondaries are as dark on Hutton's. These feathers are more dusky and generally look greenish rather than black. Additionally, the outer webs of the greater coverts (again right above the lower wingbar) lack the bright yellow edges that can be seen on the same feathers of a Ruby-crowned Kinglet. Collectively, these differences combine to make the wing pattern of a Ruby-crowned more crisp and contrasty than the wing of a Hutton's Vireo.
The one new thing that I noticed as I studied photos of these species is that Hutton's Vireos consistently look more scruffy faced than Ruby-crowned Kinglets. The feathering on the face and throat area of a Ruby-crowned seems to lay more neatly, giving this species a very smooth, mousy look to the head and face. However, on Hutton's the facial and throat feathering, particularly the area in front of and below the eye and down into the malar region, is often quite scruffy or ruffled-up looking.
There are two final things that I usually see when I compare these species. First, the head of a Hutton's Vireo almost always looks disproportionately large compared to the overall body size, while the head of a Ruby-crowned Kinglet seems to fit the body size better. Also–and this is mentioned in many field guides–Hutton's have a broad pale yellow loral stripe that connects with the front of the eye ring to create a slightly spectacled look. Ruby-crowned Kinglets are also fairly pale in the lores, but they generally don't show a loral stripe connecting from the base of the bill to the front of the eye ring, thus their face is quite plain.
Like most birds that are superficially similar in appearance, there is no substitute for repeated study. However, if you can commit these basic elements to memory, I think you'll quickly develop a better search image for each species. As these search images become ingrained, you'll begin to more readily see what is different and be less inclined to get hung up on the similarities. You will also start to associate differences in their appearance with the differences in their movements.
Like other vireos, Hutton's tend to feed in a hop, stop, head swivel sequence. They are more inclined to sit in one spot for several seconds at a time, all the while turning their heads back and forth looking for non-flying prey (mostly grubs and larvae). As a general rule, they don't flick their wings much and rarely go after prey on the wing. That said, Hutton's Vireos tend to flick their wings and flit around more than other vireo species, which are even more deliberate and lethargic in their movements. Compared to Hutton's Vireos, Ruby-crowned Kinglets are perpetual motion. They flick their wings frequently as they move about and often jump or flit into the air after prey (including flying insects). They also hover as they glean prey from the undersides of leaves.
For most birders, encounters with Ruby-crowned Kinglet far outnumber their encounters Hutton's Vireo, which has a more limited range and is more habitat specific. I can't over-emphasize the importance of studying common birds. You'll be surprised by what you notice when you take a closer look at birds that you already easily recognize. If you don't occasionally take the time to linger on a Ruby-crowned Kinglet and come to know it well, your chances of recognizing a Hutton's Vireo when one is before you will be greatly diminished. Hopefully, these hints will get you started down the path of readily identifying and recognizing these two species.
Only a handful of species show the range of geographic variation that one can see in Song and Fox Sparrows. You may have a good handle on the forms that occur close to where you live, but if you travel about the continent you may come face to face with individuals that leave you wondering which species you are looking at. This is particularly true in the Pacific Northwest, where the "coastal" forms of Song Sparrow are slightly larger and significantly darker than those found along the East Coast and across the interior of the U.S. and Canada.
Sooty Fox Sparrows further complicate matters. Not only are they quite different in appearance than the more easterly Red Fox Sparrow, but for much of the year you will find them in the same brush patches with the equally unfamiliar looking Song Sparrows of the Pacific Northwest. This article offers some key field marks to look for if you find yourself struggling to separate these species away from your home patch. The best part is, you don't have to have them side by side to sort them out.
A good starting point is bill color. Unlike Fox Sparrow, the bill color of Song Sparrow doesn't change much throughout the year. Their bills almost always look uniform in color. Both mandibles are a dark and dusky grayish horn color. Only recently-fledged juveniles will show paler fleshy yellow tones on the bill. The bill color in Fox Sparrows is far more variable and changes seasonally. During the breeding season, their bills are generally paler, ranging from pale grayish to dull grayish-pink. Outside the breeding season (October-March), Fox Sparrows will a darker bill color, particularly the upper mandible, with varying amounts of corn yellow on the lower mandible and along the cutting edge of the base of the upper mandible. Birds seen from March-May will show a gradual reduction in the amount of yellow on the bill (Irons 2012). These seasonal transitions in bill color seem to hold true across all four Fox Sparrow groups (Red, Slate-colored, Thick-billed, and Sooty).
The next thing to look at is the face pattern. All subspecies of Song Sparrow have a well-defined brown or reddish-brown post-ocular stripe that is surrounded by gray or buffy-gray and extends from the back of the eye towards the nape, where it generally flares slightly. In the West, there are three groups of Fox Sparrow subspecies. Sooty, Slate-colored, and Thick-billed Fox Sparrows all lack the strong face pattern that we associate with Song Sparrows and Red Fox Sparrows. Although Red Fox Sparrows have a strong gray and russet face pattern, the auricular patch is usually fairly solid reddish-brown, thus there is no clearly defined brown or reddish-brown post-ocular stripe.
With a good view of the bill color and face pattern, you should be able to readily separate Fox and Song Sparrows, regardless of where you are in North America. By focusing on these two aspects, you can side-step the confusion that is introduced by all the geographic variation in color and you won't get waylaid by Song Sparrows that show a darker or more reddish-brown appearance.
There are a couple of secondary field marks that may help you confirm that you've made the correct identification. First, the lower rumps and tails of Fox Sparrows are almost always noticeably more reddish than other aspects of the bird. In looking at the Fox Sparrows in the images above, even though the overall tone of these birds is quite variable, you might notice that the tails and lower rumps are slightly more reddish on all of these birds. If you look at the tails of the Song Sparrows, they tend to match pretty closely to the general color of the upperparts and don't contrast with the rest of the bird. The Song Sparrows are also somewhat streaked on the rump, while the Fox Sparrows show unstreaked rumps.
Finally, the dark markings on the underparts of Fox Sparrows tend to be more crisp with lots of isolated triangles/chevrons and if you look closely at the streaking you can see that the streaks are actually rows of chevrons. Song Sparrows tend to have blurrier streaking, with very few isolated chevrons and the streaks don't appear to be made up of rows of chevrons. Below are sets of images of both Fox and Song Sparrows that illustrate this difference.
I'll conclude this photo essay with a bird (see photo below) that might cause a bit of a problem. It was photographed in Michigan during April by Allen Chartier. It shows a quite a bit of gray in the auriculars, which are bordered by russet above and below. It also has the suggestion of a post-ocular stripe, although it is thinner behind the eye and connects to the auriculars rather than dead-ending at the nape like it would on a Song Sparrow. Other clues include unstreaked rump and the tail and lower rump, which are considerably more rusty reddish than the rest of the bird. Finally, if you look closely at the bill, it is still showing some yellow on the lower mandible. We can't see much of the underparts, but otherwise the sum of the parts of this bird add up to Fox Sparrow.
I will continue to look for pairs of potentially confusing common birds as subject matter for this sort of article. If you have certain birds or groups of species that you wrestle with, feel free to let me know via a comment. We welcome your feedback about these articles and suggestions for future ID articles.
While birding a local wetland today, I encountered another birder peering at a modest flock of small sandpipers through his spotting scope. Just before offering my usual "have you seen anything interesting?" I noticed that he had an open field guide in his hand. So instead, I asked, "what are you working on? "I'm trying to sort out Least and Western Sandpipers" he replied. Over the next couple of minutes I offered some pointers and hints about shape, bill length, leg color and where these two species tend to feed. He was appreciative and I moved along hopeful that my assistance had been useful.
It's always good to be reminded that ID issues that you may have worked out long ago are hurdles that newer birders may still be navigating. I don't know how many hundreds of thousands of Least and Western Sandpipers that I've looked at over the past four decades, but it's a large enough number that they are as familiar to me as my own family members. I can readily recognize these species at a distance, often without giving the slightest thought to how I'm doing it. As I walked away from this encounter, it occurred to me that my ability to share meaningful ID hints might be hampered by this familiarity, so I spent the next thirty minutes or so taking comparative photos of these two species as they fed together in the shallows. As I did this, I tried to get shots from many angles and with the birds in the same relative feeding positions. Later, while editing the photos on my computer monitor, I attempted to look at them with a fresh eye. I also forced myself to think about the visual triggers that I use to sort them to species and convert those subconscious clues to more conscious clues that I might better explain in the future.
Field guides will tell you that Least Sandpipers have yellow or greenish-yellow legs and Westerns have black legs, thus you would think this difference would be easy to see. All too often it isn't. Juveniles and often basic-plumaged adults have darker olive-green legs. If the legs are under water, as they often are in feeding birds, it doesn't matter what color they are. If you are out birding in August and September , when the bulk of the southbound migration of Least and Western Sandpipers occurs, you may be doing so under bright sunny skies. When the sun is high (midday), the bird's body will shade the legs making them look dark. Lower sun angles produce backlighting that will also render this field mark unusable.
In looking at the photo above, I notice several aspects of color and pattern that I use semi-consciously in separating these birds, especially from a distance, or in situations where the tell-tale leg colors are not discernible. First and foremost, at all ages and in all plumages Least Sandpipers are darker and browner overall than Western Sandpipers; winter adult Leasts are darker gray. Additionally, they are darker and more heavily marked on the breast, particularly the juveniles. Hatch-year Western Sandpipers (juveniles) and adults in basic plumage are essentially unmarked and white on the breast. They may have a little bit of streaking on the sides of the upper breast and extremely fresh juveniles may show a wash (no streaking) of cinnamon buff across the upper breast. Juvenile Leasts have variable amounts of streaking across the entire breast and the breast is usually has a dull brownish wash as well.
Secondly, the I look at head and face patterns. Westerns are paler-faced overall with limited dark feathering in the auriculars and a paler, gray cap. Leasts have a more solidly dark brown cap and extensive dark feathering in the auriculars, both of which accentuate the white supercilium. From a distance, the supercilium of a Least stands out, while the supercilium of a Western is more blended into its pale face.
Finally, I notice whether the rusty scapulars–the feathers between the top of the folded wing and the middle of the back–contrast with the back and rest of the folded wing and wing coverts. The scaps on a juvenile Western tend to stand out and contrast noticeably with nape, back, and coverts, which on a juvenile Western tend to look colder and gray as they do in the photo above. Conversely, a juvenile Least has a warmer, browner nape, back and wing coverts that do not contrast with the scapulars.
There are some elements of shape and proportion that provide helpful clues when trying to separate these birds. Westerns are longer billed and their bill tips tend to be thicker and more blunt than the bill tip of a Least. Further, Westerns often look slightly hump-backed and a bit more chesty and broad across the shoulders. Leasts generally show a straighter back profile, are not as chesty and at times seem to be thickest at the belly rather than thickest in the upper torso like a Western. Beware that the torso profile is at best a subjective feature when sorting these two species and the way the feathers are laying can easily alter our perception of body shape.
Additionally, there are a couple of behavioral clues that may be useful. Westerns are more likely to be out in the water and feeding belly deep, although the photos here show that either species will feed this way. Leasts are more inclined to feed up on mud completely out of the water and away from the water's edge. When feeding in the water, Westerns seem to tip forward more and I think they are more likely to have their tails pointing upward. Leasts tend to have more horizontal feeding posture, particularly in very shallow water or on dry land. They often squat slightly with bent legs, while Westerns tend to stand more straight-legged and tip forward at a steeper angle.
Hopefully, these tips will be of use to folks who are still learning the small calidrids, particularly along the West Coast of North America, where Least and Western are the predominant "peeps." However, there is no substitute for spending hours watching these birds feed and interact in mixed flocks, as this is the best way to discover the visual or behavioral clues that consistently work for you. In my own case, I tend to see shape, posture, and overall proportions before I notice color or other aspects relating to plumage. Others may find that they first notice differences in plumage or soft part coloration. If you've found useful field marks not mentioned in this article, I invite you to share them as a comment.
While birding east of Portland, Oregon on 4 August 2013, Shawneen Finnegan, Rich Hoyer and I found an odd-plumaged pale swallow in a large mixed group of Tree, Violet-green, Barn, Cliff, Northern Rough-winged and Bank swallows. It was mostly white below and the areas of the upperparts that would typically be dark, were instead pale silvery gray.
I took several photos of the bird and we watched it on and off for nearly 45 minutes. Based on what I could see, I thought it was a hatch-year Bank Swallow. It was smaller than most of the other swallows and by direct comparison it appeared slightly smaller and shorter-winged than a Violet-green Swallow when perched. It spent most of the time perched on the wires with about 200 other swallows, so we got a good feel for its size and proportion. We did see it fly a couple of times. In flight, the shape and proportion seemed to best fit Bank Swallow in my opinion. Rich thought that it might be a Tree Swallow.
I've seen a number of leucistic or at least partially leucistic swallows over the years. They have been either white/or dappled white, or in a couple of cases creamy-tan overall. None displayed this sort of silvery-gray quality. In fact, until recently, I had never seen any species of bird that showed this sort of gray plumage anomaly. Just recently, Cathy Sheeter found and photographed a mostly gray Swainson's Hawk (I believe in Colorado), which had essentially no brown coloration. She shared the images with Jerry Ligouri, who posted them on his blog. http://jerryliguori.blogspot.com/
I've spent quite a bit of time online trying to find references to similarly plumaged swallows and found none. I also couldn't find any references to plumage anomalies that involved darker feathering being replaced by gray feathers. If anyone is aware of a description/explanation of this plumage aberration, I would like to learn more about it.
...an immature is not always a juvenile.
When talking about the age of a bird, the terms juvenile and immature are not interchangeable. Strictly speaking, one should only refer to a bird as a juvenile during the period when it wears its first complete set of feathers. Once a bird begins to replace feathers from the original set, it is no longer a juvenile. Depending on the extent of the first molt, the subsequent plumage aspects may be referred to as formative, first basic, or, in the case of species that require several years to reach a definitive adult plumage (i.e. gulls, terns, raptors), first-cycle.
For most species, the juvenile plumage is very short-lived. This is particularly true of songbirds. Many migrant songbirds hatch, grow a set of feathers, fledge, and then replace a majority of the original feather set before they ever leave the nesting grounds. For many such species, wing and tail feathers are the only elements of the juvenile plumage that are retained. It is simply too taxing on the bird to replace the longer, more durable flight and tail feathers so soon after growing the first set.
If you see a hatch-year thrush, warbler, or sparrow in July and then see that same bird in September, its appearance will have changed dramatically. Think of what an American Robin, Yellow-rumped Warbler or Dark-eyed Junco looks like when it is still being fed by an adult. By the first of October, you won't be seeing spots on the breast of the robin and the uniform streaking that marked the underparts of the warbler and the junco in July will be long gone.
The convenient thing about songbirds is that they tend to transition from juvenile plumage into an appearance that is very much like that of an adult, or at least a winter adult. Unless you understand how to use molt limits, visually separating many six-month old songbirds from their parents will be difficult. However, some species exhibit intermediate aspects that are distinctly different from both the juvenile and adult plumages. Birds in these plumages should not be referred to as juveniles. It is best and most accurate to describe such a bird as an immature or, perhaps, a sub-adult.
The term juvenile is most often misapplied to gulls, eagles and hawks. These groups of species take multiple years to acquire definitive adult plumages. Unlike the majority of songbirds, they will go through a series of distinctive plumage cycles all of which might be considered to be immature or sub-adult. Three-year and four-year, white-headed gulls offer probably the best known example of plumage cycles.
When white-headed gull species hatch, most grow a set of feathers that is mostly brown or gray-brown, rather uniform, and spangled or mottled. Sometime during the fall or early winter of their hatch year, they will undergo a preformative molt. The most obvious feather replacement will be on the back/mantle, head, and breast. The juvenile mantle feathers, which have dark dusky-brown or gray-brown centers and pale buffy or grayish edges, will be replaced by medium to pale gray feathers that are uniform in color with little if any interior pattern. By the end of the first winter, the heads of birds in this group will be extensively white with some darker streaks and smudges rather than almost entirely brown or gray-brown, as it was in juvenile plumage. Finally, the breast, which was densely streaked and looked mostly dark in juvenile plumage, will end up mostly white or off-white with more limited to non-existent streaking.
Despite the extensive alteration of the head, back, and body pattern, the wings will continue to look brown and mottled because the flight feathers have not been replaced during the preformative molt. Over the next 8-9 months, the first set of flight feathers will usually become worn and in some cases heavily sun-bleached. They will look old and tattered compared to the newer feathers acquired during the preformative molt.
Another groups of birds with distinctive juvenile plumages are shorebirds. Like gulls, they leave the breeding grounds in juvenile plumage and hold that first plumage aspect well into their first fall. Most species, particularly the long-distance migrants, will not start their preformative molt until they reach their wintering grounds.
When the initial North American field guides appeared, it was as if juvenile birds and their plumages did not exist. They were generally not illustrated and if they were the illustrations were not properly labeled and juvenile plumages were not discussed in the text. The first Peterson guides actually offered black-and-white illustrations of "fall" shorebirds. For the most part, these illustrations showed juvenile birds, but did not label them as such or account for the fact that one might also see alternate and basic-plumaged adults during Fall.
The 1st edition of the National Geographic Guide (now in its 6th edition) followed the lead of British and European field guides and became the first North American field guide to thoroughly illustrate, describe, and properly label the juvenile plumages for shorebirds and other species groups. The Sibley Guides raised the bar again by accurately showing the date range (in months) that one can expect to see each particular species in its juvenile plumage. Having access to illustrations or photos that show all the different aspects that a bird might present and understanding the time of year that they might look a certain way is vital when it comes to identifying most birds. As an example, if you see a bird in January that looks like the juvenile junco in the top image, you can be pretty comfortable in concluding that it's not a junco based on seasonality. In fact, Sibley indicates that birds of this appearance are only likely to be seen from May thru August.
As you can see from the three Western Sandpipers in the photos above, understanding how a bird's appearance varies with age and time of year is critical. If you saw the birds in the top image together on the same day–as I did– it would be easy to conclude that they were of different species. On occasion, a winter/non-breeding aspect Western (like the Baja bird) will show up with the southbound migrants (alternate-plumaged adults and juveniles) in August or September. Imagine a newer birder seeing a flock with birds representing all three plumages/aspects (it happens), and then being told by an experienced birder that all of the birds were of the same species.
If you intend to properly convey what you've seen to other birders, it helps to describe them in terminology that will be understood and terms that accurately represent the age-class that you observed. When describing a bird as a juvenile, it is important to understand what that label implies. It's perfectly okay to not know, or not be certain of a bird's age, as it's not always readily evident. While some might figure out that you mean immature or subadult when you call a bird a juvenile, others may be left searching for your discovery armed with a false notion of what they are seeking.
Finally, this subject cannot be discussed with out addressing the question of "juvenile" vs "juvenal," which causes confusion for some. Juvenile can serve as both a noun or an adjective, whereas juvenal is strictly an adjective, most often applied to describing the first plumage of a bird. In my view, whether you say juvenile plumage or juvenal plumage, most birders will understand what you are trying to say. However, among experts there has been some disagreement regarding the importance of using "juvenal" when describing the first plumage of a bird or in describing the molts that produce or alter that plumage. For example, a bird replacing its juvenal/juvenile feather set might be described as undergoing a post-juvenal molt. However, if you are talking about the bird itself, it can only be referred to as a juvenile. You might say, "I saw a juvenal-plumaged Song Sparrow, but it is not appropriate to say, "I saw an adult Song Sparrow feeding two juvenals." For a lively and thought-provoking discussion, I would recommend reading Joe Morlan's thoughts on this topic. He wrote a letter to the editor of Birding in response to a letter to the editor that Steve N.G. Howell had written in 2009, in which Howell endorsed the idea of abandoning the use of "juvenal." Morlan Letter to Birding I don't have a dog in this fight, but for the sake of simplicity I use "juvenile" as both the noun and the adjective when discussing birds.
Glossary of potentially unfamiliar terms:
Note: Most of these definitions below come directly from "Molt in North American Birds" (Howell 2010). This is the most recent, comprehensive treatment of this topic and is a great place to start if you are interested in learning more about molt sequences. I have chosen to use Howell's precise definitions in an effort to avoid introducing any further confusion to a topic that already creates confusion for many birders.
Alternate Plumage -- Any second plumage in a cycle in addition to–and which alternates with–basic plumage. Attained by a prealternate molt.
Aspect -- The overall appearance of a bird, which can be a composite of basic and alternate plumages. For example, larger white-headed gulls with clean white manifest a breeding aspect, even though they may not be breeding or may have started their prebasic molt. European Starlings in glossy, mostly unspotted plumage manifest a breeding aspect, even thought this is simply their worn basic plumage.
Basic Plumage-- The plumage attained by the prebasic molt (which is complete or nearly so)and presumed to be homologous in all birds.
Cycle -- A regularly repeated phenomenon, such as a plumage cycle. A basic plumage cycle extends from the start of one prebasic molt to the start of the next prebasic molt. The first plumage cycle extends from the acquisition of juvenile plumage to the start of the second prebasic molt.
Definitive Plumage -- A plumage whose aspect does not change with time.
Formative Plumage -- Any plumage present only in the first (that is, formative) year of life and lacking a counterpart in subsequent cycles. Attained by a preformative molt. Most conventional "first basic" plumages are formative plumages.
Four-year -- Refers to a group of large gulls that go through four complete plumage cycles before attaining a definitive adult plumage. May or may not happen within four calendar years.
Immature -- A general term for any nonadult plumage, including juvenile plumage.
Juvenal -- An adjective that is interchangeable with "juvenile" when describing the first plumage of a bird or the molts that produce or alter that plumage. Howell (2010) does not use this term, calling it a "psuedo-academic distinction that is unnecessary."
Juvenile -- A bird in juvenile plumage (see definition below)
Juvenile Plumage -- The first plumage of "true" or vaned (nondowny) feathers; often the plumage in which a bird fledges. Considered synonymous with "first basic plumage" in recent molt studies and attained by the prejuvenile (first prebasic) molt.
Molt Limits -- (called "Molt Contrast" by Howell) The point of contrast between two generations of feathers in a non-molting bird; for example, between the alternate and basic primaries of a tern.
Plumage -- There are two meaning for this word. In the Humphrey-Parkes System, refers simply to a generation of feathers attained by a molt, and the color of the feathers is not relevant. In everyday usage, refers to a bird's coat of feathers and may be termed "male plumage," "immature plumage," "breeding plumage," etc; thus the color and pattern of the feathers are relevant.
Preformative Molt --The molt by which formative plumage is attained. In traditional Humphrey-Parkes terminology this was called the first prebasic molt.
Three-year -- Refers to a group of medium-sized gulls that go through three complete plumage cycles before attaining a definitive adult plumage. May or may not happen within three calendar years.