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Since the Solitary Vireo was split into three species (Blue-headed, Cassin's and Plumbeous Vireos), birders have struggled to separate these taxa when any one of them is reported outside of its normal range. In the Fall, separating putative Blue-headed Vireos on the West Coast is complicated by the fact that freshly-molted Cassin's Vireos are nearly as bright, colorful, and contrasting in plumage (Heindel 1996). Similarly, a suspected Cassin's Vireo found east of the Rocky Mountains must first be proven not to be a Blue-headed.
Vireos sport their brightest and most contrasting appearance in the Fall after going through their only molt cycle of the year. Like other vireos, Cassin's Vireos seen during Spring and Summer can be quite dull and virtually colorless. The contrast and color one sees in the Fall are lost to feather wear and fading. During this season, it's hard to imagine how a Cassin's might be confused with a Blue-headed, but Plumbeous...that's another story.
One of the by-products of any species split is a predictable surge in reports of the new species from locales where the former subspecies was either never, or rarely recorded. Trying to get a handle on the actual status and distribution of the new taxon can be a challenge because the first wave of such sightings comes before field guides catch up and authoritative ID articles are published. As we rush to fill the blank spots on the new scorecard, we do so without the help of well-vetted resources. Most birders don't concern themselves with trying to recognize subspecies, but once one is elevated to full species status and becomes available for us to tick off, the sense of urgency to do so ratchets up.
The breeding range of Plumbeous Vireo spans most of the Great Basin–Nevada, s. Idaho, Utah, w. Wyoming, n. and e. Arizona, and much of New Mexico (Goguen and Curson 2012). The northernmost breeding records are from Montana and to the south the breeding range extends into Mexico along the Sierra Madre (Goguen and Curson 2012). Although some presume that this species breeds in Oregon, there is no clear evidence for this being the case.
Prior to 1997, when Plumbeous Vireo attained full species status, there were but a handful of colloquial and published "Plumbeous" Solitary Vireo records from Oregon. Most were not fully documented. Additionally, no specimen taken in Oregon has ever been assigned to this form. However, with the anticipation and eventual assignment of full species status the occasional claims of a Plumbeous Vireo, which formerly came every few years or so, have mushroomed into multiple reports per year.
Most of Oregon's reports of Plumbeous Vireos have fallen late May to early June. The majority of such sightings coming from desert oases/migrant traps in the southeastern corner of the state, where visiting birders arrive primed and ready to find vagrants. Note that this section of Oregon is sparsely populated and only a handful of active birders live in this subregion. I'm not quite sure how, or why it happened, but in the wake of the species split the Oregon birding community quickly came to accept that Plumbeous Vireo should be expected in southeastern Oregon at this time of year and that it probably breeds semi-regularly in this corner of the state. The evidence supporting either of these notions is at best, scant. There are but seven reports of Plumbeous Vireos that have been accepted by the Oregon Bird Records Committee (OBRC). Four of these are single-observer sight records and only two of the seven accepted records are supported by photos.
The species account in Birds of Oregon: A General Reference (BOGR) may have contributed to the misunderstanding of Plumbeous Vireo's status in Oregon (Nehls 2003). It starts by stating that the status of this species is "poorly understood." Then, there is a cautionary note about identification, which references Matt Heindel's excellent ID article published in Birding (Heindel 1996). It further points out that there are no Oregon specimens. Following these caveats, there is a roster of 11 cited records, including a putative nest found along Kelly Creek in southern Lake County in 1996. Apparently, the nest site was logged shortly after this discovery, thus no further documentation or photos were obtained. The account also offers that the species "has been reported in Harney County every spring since 1992." It's hard to read this account and not come away believing that the regular occurrence of Plumbeous Vireo in Oregon is well established. Many of the reports listed in BOGR (Nehls 2003) were never submitted to the OBRC and of those that were, two were not accepted.
The issue with over-reporting of Plumbeous Vireos is not confined to Oregon. In California, ballooning spring reports of this new species from that state's coast and desert oases have also raised questions (Paul Lehman pers. comm.). According to Lehman and others, Plumbeous Vireos are still "scarce-to-rare" during Spring even in Southern California, despite an apparent increase in the numbers found there during fall and winter. Away from Southern California (Los Angeles south) Plumbeous Vireos are casual visitors at any season. Long-time North American Birds regional editor Guy McCaskie is of the opinion that there are only a few "ironclad" spring records from Southern California and that all good records are from the desert, with coastal reports being suspect (Lehman pers. comm.). As they have been in Oregon, reports from California's desert outposts are often poorly documented, as many birders believe that a spectacled vireo seen in desert/Great Basin habitats is by default a Plumbeous. From Oregon, Alan Contreras points out that northbound Cassin's Vireos continue to trickle through Harney County oases into early June, even though this species is not thought to breed in Harney County, or neighboring Malheur County to the east.
When seemingly credible sources repeat the same thing with enough frequency, claims that lack hard supporting evidence gain traction and start to become accepted 'fact.' Political parties are experts at this sort of manipulation of reality, often swaying public opinion with the repetition of half-truths, or murky data.
The birding world is not immune to being influenced by apparent critical mass. Unlike the manipulation that occurs in the political arena, birders tend to unknowingly perpetuate fallacies. When visiting sites where vagrant birds are found regularly, or birding a locale where a desired species is "expected," it can be a challenge to avoid the pitfalls that accompany expectation. Objectivity and healthy skepticism are too often replaced by an excited mind that is ripe for being duped. It's not hard for us to shoehorn the first plausible candidate into a species that we are hoping to see. It becomes easy to overlook what one subconsciously doesn’t ‘want’ to notice and see only those aspects of the bird that seem to best fit the species that one hopes to add to their list. If you’ve been birding for any length of time, you’ve probably stepped into this pothole a time or two.
When birding desert migrant traps in southeastern Oregon–where Cassin's Vireos are low density spring migrants–the sight of an apparently dull and colorless spectacled vireo gets the blood pumping. If the bird stays inside the canopy and out of direct sunlight (typical for this species group), it's not going to be difficult to convince yourself that you aren't seeing yellows and greens in the plumage, because you probably aren't. Even knowing how dull Cassin's can be in the spring, I have twice been fooled into thinking that I might be looking at a Plumbeous in Oregon, only to have my camera or exposure to direct sunlight reveal color that I wasn't seeing when the bird was in the shade. Even in good light, the subtle colors of a spring Cassin's come and go with changes of angle.
At this point, the actual status of Plumbeous Vireo in Oregon remains a mystery, in part because our birding community has applied little rigor to the examination of reports of this species. Acceptance of a presumed status is based almost entirely on a set of unreviewed or undocumented reports, hence there is a prevailing notion that reports of this species don’t require thorough documentation. I contend that we should start from ground zero and start treating Plumbeous Vireo as though this species is extremely rare in Oregon, which it may well be. Only then, will we be able to get a handle on their actual status. Getting that genie back into the bottle is easier said than done.
Goguen, Christopher B. and David R. Curson 2012. Plumbeous Vireo (Vireo plumbeus), The Birds of North America Online (A. Poole, Ed.) Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell,edu/bna/species366 doi:10.2173/bna366
Heindel, M.T. 1996. Field identification of the Solitary Vireo complex. Birding 28:458-471.
Nehls, H. B. 2003. Plumbeous Vireo. p. 401 in Birds of Oregon: A General Reference. D.B. Marshall, M.G. Hunter, and A.L. Contreras, Eds. Oregon State University Press, Corvallis, OR.
Intersex -- The condition of being intermediate between male and female
A few weeks back, a birding acquaintance of mine sent me photos of a Wood Duck that he had photographed at Dawson Corporate Park in Hillsboro, Oregon about 15 miles west of downtown Portland. The duck displayed a plumage that left him scratching his head. In his email he wondered, "is this a young male or maybe a hybrid?" It was neither. Almost immediately, I recognized that it showed a mix of both female and male characteristics, which led me to conclude that it was probably an intersex Wood Duck.
Intersex ducks are fairly well known and if you poke around you can find a fair amount of information and many photos of intersex birds on the Internet. However, in one aspect, gender-challenged ducks are different from other intersex birds.
In most bird families, the female plumage aspect is the default appearance. Like humans, the production of sex hormones wanes in birds as they start to age. This results in males taking on a more female-like appearance as they go through annual molt cycles. In ducks, it's the exact opposite, with older females gradually taking on the appearance of the male.
I visited the Dawson Creek ponds on 15 November 2013 and refound the bird. While there, I ran into another local birder, Steve Nord, who told me that this individual has inhabited this location for about five years. It's hard to know if there is a typical age when the transition starts to occur, but the account below, excerpted from a 1992 Dutch Birding article, chronicles the transition of a hand-raised female Mallard.
On 12 August 1977, four deserted Mallard Anas platyrhynchos ducklings were found and subsequently hand-raised [and ringed; RvdV]; they fully matured and lived for many years as garden pets in Goes, Zeeland. After c 10 years, one of the females gradually started to show male plumage and bare part characters. Within the group (now consisting of seven birds), however, the female still behaved as a females\ and was also treated like a female by the other ducks (which usually is not the case). The bird died on 3 September 1991. Dissection revealed that the left ovary and part of the oviduct were cysteous, possibly as a result of age. The right ovary, however, was still in its normal embrynic state. Birders are regularly confronted in the field with ducks that show incompletely developed adult male plumage characters. Although these are often moulting or juvenile birds, there is a possibility that they are females showing male plumage and bare part characters due to an ovarian abnormality." (http://fog.ccsf.edu/~jmorlan/feb00.htm)
Taking a closer look at the ducks at your local duck pond is likely to reveal a Mallard or perhaps another duck that exhibits the appearance of an intersex bird. Look for birds with male plumage and a female bill pattern. Over the past two years I've seen at least two presumed intersex Mallards. Both had some green on the head, some gray on the flanks and yet the bill was a mix of orange and black typical of a female, rather than a solid yellow-green straw-colored bill of an adult male. Several examples of presumed intersex Mallards can be seen at the link below:
Post J. N. P. and E. J. O. Kompanje 1992. Uitwendige geslachtsverandering bij vrouwtje Wilde Eend. Dutch Birding 14 (4): 131-134.
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.