Maryland / District of Columbia Records Committee Skins Workshop 22 January Edited by Bill Hubick, MD/DCRC Chair

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1 Maryland Ornithological Society 1. General Maryland / District of Columbia Records Committee Skins Workshop 22 January 2011 Edited by Bill Hubick, MD/DCRC Chair On 22 January 2011, the Maryland/District of Columbia Records Committee (MD/DCRC) held its annual Skins Workshop at the Division of Birds, National Museum of Natural History, Smithsonian Institution, Washington, DC. Our host was Roger Clapp of the US Geological Survey Biological Resources/Patuxent Wildlife Research Center, who is resident at the museum. The committee wishes to thank Roger for the time he dedicated to our workshop. The agenda and taxa to be reviewed during the workshop (and species account author) included the following: Taxa Authors 1. Peucaea Sparrows Bill Hubick and Mikey Lutmerding 2. Common and Arctic Terns Fred Shaffer 3. Anna's/Ruby-throated/Black-chinned Hummingbirds Tyler Bell 4. Northern and Loggerhead Shrikes Ron Gutberlet 5. Carolina and Black-capped Chickadees Mike Bowen 6. "Black-backed" Robin Walter Ellison 7. Winter and Pacific Wrens Fred Shaffer Note that the official museum database and specimen tag abbreviation for the Smithsonian is USNM, based on its original name, United States National Museum. 2. Attendees Committee members in attendance were: Mike Bowen, Walter Ellison, Ron Gutberlet, Joe Hanfman, Fred Shaffer, Bill Hubick, Mikey Lutmerding, Tyler Bell, Gwen Brewer, Paul O'Brien (Chair), and Phil Davis (Secretary). 3. Skins Studies We began the workshop at 10:00 am, following our security check-in. We assembled in the Birds Division specimen case area on the sixth floor. Our objective was to study specimen skins related to sighting reports that are currently in review or are expected to be reviewed over the next year or skins that relate to potential identification problems for Maryland and DC. The findings from the specimens we examined are summarized below. Page 1 of 45

2 Photo 2-1. Committee members studying skin specimens. Left to right: Ron Gutberlet, Walter Ellison, Fred Shaffer, Paul O'Brien, Mike Bowen, Bill Hubick, and Mikey Lutmerding. Photo by Phil Davis. 3.1 A comparison of Peucaea sparrows: Cassin s Sparrow (Peucaea cassinii), Bachman s Sparrow (Peucaea aestivalis), and Botteri s Sparrow (Peucaea botterii) Account by Bill Hubick and Mikey Lutmerding Background. On September 26, 2010, Mikey Lutmerding found and photographed a Peucaea sparrow that is widely regarded to be a Cassin s Sparrow. Now accepted (# MD/ , Point Lookout State Park, St, Mary's County. MD), this report represents not only a new state record, but one of the very few vagrant records for the East Coast. It is a rare enough vagrant that it received not a single mention among the 63 species nominated in the 2009 Maryland s Next 10 Bird Species poll (Hafner/Hubick). Cassin s Sparrows are found in the arid central and southern grasslands south to the northern half of Mexico. Birds of North America notes vagrant records from Utah (3), Nevada (2), Illinois (1), Indiana (2), South Dakota (1), Michigan (1), Ontario (6), New Jersey (1), Maine (1), and Nova Scotia (1). Additional vagrant records were documented in 2011 in Massachusetts, North Carolina, and Ohio. Bachman s Sparrow is a pine woods specialist of the southeastern U.S. It is a historic breeding species in the state, nesting locally on the western shore of Maryland, particularly in the Ridge and Valley, until the 1970s. The most recent reviewable record is from Sycamore Landing, Montgomery County, on October 7, Botteri s Sparrow is a Central American grassland species with a range that barely reaches southeastern Arizona and southernmost Texas. It is not a likely candidate for vagrancy to the East Coast but is treated to a limited extent in this account for the sake of thoroughness. Page 2 of 45

3 3.1.2 Findings To prepare for the review of the September 2010 report, the committee compared Smithsonian Institution Peucaea specimens collected in the fall. We focused on the separation of Cassin s (P. cassinii) and Bachman s (P. aestivalis) Sparrows, but also included the less likely Botteri s Sparrow (P. botterii). We started with overall impression, comparing full trays of the three sparrow species and discussing the obvious differences. We noted that Bachman s Sparrows were much warmer plumaged than Cassin s Sparrows and Botteri s Sparrows. There were consistent differences noted both dorsally and ventrally. Viewed ventrally, we noted in particular the warm brownish tones in the upper breast of Bachman s Sparrow. This feature appeared consistent across ages and subspecies. Cassin s Sparrow specimens were duller and grayer overall and never approached the warm coloration in breast marking. A single Cassin s Sparrow placed in a tray of Bachman s Sparrows was easily and repeatedly picked out. Even comparing the warmest toned Cassin s with the coldest toned Bachman s, the differences in lowerparts was obvious (see Photo ). Botteri s Sparrow lowerparts were very similar to those of Cassin s Sparrows. General impressions of upperparts were consistent as well. Cassin s Sparrow specimens had a bluish gray cast to their upperparts, while Bachman s Sparrows were decidedly reddish brown. This major difference in impression could be conspicuous even under most field conditions. Botteri s appeared grayish overall, darker than Cassin s. We noted consistent differences in crown markings. Cassin s Sparrow crown feathers were a three-color mix of gray, brown, and black (see Photo ). The black centers were rounded and surrounded by chestnut brown fringed in gray giving a more speckled appearance. Botteri s Sparrow (see Photo ) crown markings were similar to those of Cassin s Sparrow, with a three-color mix of gray, brown, and black; the black centers were more elongated giving the crown an overall streaked appearance. In Bachman's, the crown was a mix of reddish brown and gray, with perhaps a slightly darker reddish brown center to some feathers (see Photo ). This imparted a streaked reddish brown and gray look to the crown. The mantle feathers of each species were unique when viewed at close range, and seemed a continuation of the crown feather pattern. On Cassin s, the individual feather had a dark central spot (perhaps a couple of shades lighter than black) sometimes with points radiating out giving the appearance of an anchor, this was surrounded by a deep chestnut with a gray fringe that was thicker laterally (see Photo ). An individual Bachman s mantle feather shows a rich bright rust color that extended along the feather shaft to the tip with a lateral fringe of gray (see Photo ). Occasionally, there was a slightly darker shade of brown along the feather shaft. Botteri s mantle feathers showed a dark center that was perhaps a shade lighter than black (see Photo ). Broad at the base and thinning to the tip of the feather, there were lateral brown markings surrounded by a gray fringe. These qualities imparted unique patterns from a distance with Cassin s looking overall speckled, while Bachman s and Botteri s appeared overall streaked though in markedly different hues as described above. Cassin s Sparrow showed bold cream-colored edging to the tertials and secondaries, which continued to a limited extent on the primaries. In Bachman s Sparrow, the secondaries were edged lightly or not at all, but edging was a warmer reddish tan, while the tertials were edged in a bright reddish brown on the outer edge, on the closed wing this gave an impression of a Page 3 of 45

4 reddish block of feathers. In Botteri's Sparrows, the remiges had cream-colored edges, thick on the secondaries and reduced on the primaries. The tertials were also heavily edged with a cream color that appeared as a block of pale on the closed wing. The outer edge pattern to the retrices as seen from below was markedly different between taxa. Cassin s consistently had the thickest brightest edging, Bachman s was reduced and a few shades darker than Cassin s, and Botteri s appeared most reduced and a few shades darker still than Bachman s. Barring on the uppertail was noted in all species, though the only species that one could attribute this barring to actual pigmentation was Cassin s which had brown feathers with dark along the feather shaft and bars extending laterally from this. In the other species, we noted that the barring present wasn t actually pigmentation but instead growth bars. One other exciting character that we noted - though not practical under field conditions - was the difference in alula coverts between Bachman s and Cassin s (see Photo ). On Cassin s there is a three-tone pattern: chestnut brown anterior of the feather shaft, dark brown posterior, surrounded by gray. On Bachman s, there is a rusty brown spot anterior from the feather shaft, and dark gray posterior fringed with pale gray. Photo : A tray of Bachman s Sparrows. Peucaea photos by Bill Hubick. Page 4 of 45

5 Photo : A tray of Cassin s Sparrows. Photo : Bachman s Sparrows Ventral view. Page 5 of 45

6 Photo : Botteri s Sparrows Ventral view. Photo : Bachman's Sparrow (above) and Cassin's Sparrow (below) - A comparison of the coldest plumaged Bachman's and the warmest plumaged Cassin's available. Page 6 of 45

7 Photo : Bachman's Sparrow (above) and Cassin's Sparrow (below) - Typical plumages in ventral view. Photo : Bachman's Sparrows bracketing a Cassin's Sparrow - Dorsal view. Page 7 of 45

8 Photo : Cassin's Sparrow (left) and Bachman's Sparrow (right). Photo : Alternating Cassin's Sparrows (odd) and Bachman's Sparrows (even) - Dorsal view - Cassin's Sparrow starts at left. Page 8 of 45

9 Photo : Alternating Bachman's Sparrows (odd) and Cassin's Sparrows (even) - Crown comparison - Bachman's Sparrow starts on left. Photo : Bachman's Sparrow (above) and Cassin's Sparrow (below) - Profile comparison. Page 9 of 45

10 Photo : Bachman's Sparrow (left) and Cassin's Sparrow (right) - Dorsal comparison. Photo : Botteri's Sparrows (left two) and Cassin s Sparrow (right) - Dorsal Details. Page 10 of 45

11 Photo : Botteri's Sparrow - Well-marked crown details. Photo : Cassin's Sparrow - Crown details. Page 11 of 45

12 Photo : Alternating Cassin's Sparrows (odd) and Botteri s Sparrows (even) - Dorsal view - Cassin's starts on left. Photo : Alternating Cassin's Sparrows (odd) and Bachman's Sparrows (even) - Dorsal view - Cassin's starts on left. Page 12 of 45

13 A gallery of over 50 Peucaea specimen images from the Smithsonian Institution visit is available at Summary Detectability is a key challenge for locating Peucaea sparrows, but careful coverage of migration hot spots in fall might produce additional records. Documentation will be critical in confirming any member of this genus to species. Page 13 of 45

14 3.2 Common/Arctic Tern Account by Fred Shaffer Background General. In Maryland, Common Tern is a fairly common coastal breeder and regular migrant throughout much of the state. Colonies are located in coastal Worcester County and along the Chesapeake Bay, primarily along the lower Eastern Shore. Conversely, Arctic Tern is found in Maryland only very rarely during migration. Although primarily a pelagic migrant, Arctic Terns can turn up elsewhere in the state. As legendary long-distance migrants, Arctic Terns are extremely rare inland. However, when they occur it can be virtually anywhere, although they seem to focus on the Chesapeake Bay and major river corridors. In addition to records from the pelagic zone, there are also accepted Maryland records from Rocky Gap State Park, Allegany County (1992) and Violette s Lock, Montgomery County (1999). There are also several reviewable reports from recent years including sightings at Hart-Miller Island, Baltimore County (1999 and 2007), Assateague Island, Worcester County (two reports from 2009), Violette s Lock, Montgomery County (2010), Jug Bay, Anne Arundel/Prince George's Counties (2010), Skimmer Island, Ocean City, Worcester County (2010), and Ferry Neck, Talbot County (2011). Taxonomy. There are two subspecies of Common Tern (Sterna hirundo): the nominate hirundo, which occurs throughout North America, and longipennis, which is a Siberian vagrant that occurs in Alaska. Subspecies longipennis is primarily separated from subspecies hirundo based on its overall darker plumage, as well as black legs and bill. Arctic Tern (Sterna paradisaea) is monotypic. This account summarizes and compares Arctic Tern with the more expected subspecies hirundo only Findings Overview: At the 2011 MD/DCRC Skins Workshop, members studied and compared specimens of both Arctic Tern and Common Tern, subspecies hirundo. We reviewed a variety of ages, and both structural and plumage differences were recorded. A variety of structural differences were observed, most notably in the head and bill. Several plumage differences were readily apparent on the upper parts, belly, breast, undertail coverts, and the extended wing. Shades of gray: Perhaps most striking of all was a difference not generally illustrated in standard field guides and only vaguely referenced in most of the published literature: the color of the gray above and below. Whereas Common Terns were a drab brownish-gray overall (gray, but with a distinct brownish wash), Arctic Terns were a much more striking bluish-gray above and below, giving them a much cleaner, sharper appearance overall. Although both species were grayish below (breast and belly), Common Terns were a brownish-gray, while Arctics were a deeper bluish-gray. This difference in shade was readily apparent for various age groups, with the exception perhaps being some juvenile birds. Page 14 of 45

15 Photo : The bluish-gray underparts are clearly seen on this tray of Arctic Terns. Photo : The more variable muddy brownish-gray underparts of Common Terns can be seen. Page 15 of 45

16 Again, this was one of the most noticeable, readily apparent differences between the species. Arctic Terns were consistently an attractive pearly-gray below with a distinct bluish tinge. The Common Terns were more variable. Some were significantly lighter below; however, even the darkest Common Terns were a dirty gray, with a brownish wash or tinge noticeable on many birds. As the committee had just looked at several trays of Northern Shrikes, it was commented that Common Terns were very similar to Northern Shrikes in gray tone and the brownish tint overall (see Photos and ). Contrast of the undertail covert: Also, the darker gray underparts of Arctic Terns contrasted strongly with their bright white undertail coverts. On Common Terns, there appeared to be much less contrast between the underparts and undertail coverts. The birds appeared much more uniform below, not showing the strikingly white and contrasting undertail coverts of the Arctic Terns (see Photo ). Photo : Even with the darker Common Terns, the difference in the shade of gray is distinct when compared with Arctic Tern. The Arctic Tern (above) has a bluish-tinged, pearly gray color overall, with contrastingly white undertail coverts. The Common Tern (below), which was one of the darker Common Tern specimens examined, was also gray, but lacking the bluish tinge. Common Tern consistently appeared more brownish-gray, with a slight brown wash to the grayish underparts. Also note how much more strongly the bright white undertail coverts of the Arctic Tern contrast with the rest of the underparts. The contrast of the undertail coverts is much less pronounced on the Common Tern. Page 16 of 45

17 Length of the tail: Another noticeable difference between adult Arctic Tern and Common Tern was the significantly longer tail of many Arctic Terns. This was evident on many specimens, with the Arctic Tern tail extending significantly past the end of the folded wings. Most Common Terns had primaries extending to roughly the end of or just short of the end of the tail. 1 Only rarely did Common Tern tails extend significantly past the tips of the wings, almost never approaching the long-tailed appearance of the Arctic Tern (see Photos and ). Photo : Note the longer tail on the Arctic Tern (above). The two terns also show the difference in the tone of the gray between the bluish gray of the Arctic with the more brownish gray of the Common (below). Photo : The difference in the shade of gray between Arctic Tern (above) and Common Tern (below) is also seen in the upperparts. 1 Stokes, page 350. Page 17 of 45

18 Wing length: Arctic Terns have a narrower, longer wing than Common Terns. While this is most noticeable on flying birds, where the difference in wing-to-body and tail proportions are best seen, it was also evident on the folded wing. Because of the longer wings, Arctic Terns show more of each individual feather on the folded primaries. Common Terns, with shorter, broader wings, showed less of each primary on the folded wing (see Photos and ). In flight, not only do Arctic Terns show a relatively longer wing than Common Terns, the wing also has a narrower appearance. 2 Photo : In addition to the longer tail length of the Arctic Tern (above), note how much more of each primary is exposed on the folder wing compared to the Common Tern (below). Photo : The Arctic Tern (above) shows a significantly longer tail than the Common Tern (below). While the tail extends well beyond the tip of the primaries on the Arctic Tern, the tip of the tail is much closer to the tip of the primaries on the Common Tern. The bluish-gray wash overall and shorter bill is also evident on the Arctic Tern in comparison to the Common Tern. 2 Alderfer and Dunn, page 273. Page 18 of 45

19 Bill and head shape: Arctic Terns consistently showed a shorter, more compact bill than Common Tern. The bills of Arctic Terns also had a straighter appearance overall, with little or none of the slightly curved or drooped upper mandible seen in Common Terns. Although the overall bill of Common Terns did not droop, the upper mandible gave the appearance of drooping slightly to meet the lower mandible (see Photo and, particularly, Photo ). And, although difficult to judge on preserved specimens, the Arctic Terns seemed to have a smaller, more rounded crown that sloped down more steeply (i.e., at a sharper angle) to meet the bill. Photo : Note the shorter, straighter bill of the Arctic Tern (above) relative to the Common Tern (below). The Arctic Tern not only has a shorter overall bill, it appears to lack the subtle curve or droop to the upper mandible. The Arctic Tern above also displays the bright white on the cheek separating the black cap with the dark gray underparts/throat. Photo : This photo demonstrates particularly well the difference in bill shape between Common Tern (above) and Arctic Tern (below). The longer bill and slightly down-curved upper mandible is seen on the Common Tern. Also note the white area on the face separating the black cap from the gray throat and underparts of the Arctic Tern. This mark is missing or less pronounced on Common Terns. Page 19 of 45

20 Pattern of the wing above and below: The published literature includes references to several key differences of the upper and lower surfaces of the extended wings. Most noticeably, adult Common Terns typically show a dark wedge on the outer primaries above, while Arctic Terns show a plain, uniform gray upperwing. 3 Pete Dunne (2006), in his Essential Field Guide Companion, notes "Forget what you may have heard about a narrow black trailing edge to the primaries. Narrow is relative. Concentrate on the upperwing. It is all silver gray - like a mirror. Common Tern's upperwing is darker gray with a black wedge at the tip. Forster's Tern's is twotoned: gray on the arm, frosty on the hand." 4 Photo shows the uniform upperwing of two Arctic Terns. Kenn Kaufman (1990) writes in Advanced Birding that The pattern of the upperside of the outer part of the wing created by the relative shades of gray of each individual primary feathers is an important field mark for adult birds. 5 Arctic Terns have the most uniform upperwing of the four terns evaluated by Kaufmann in Advanced Birding (Common, Arctic, Forster s, and Roseate) in summer. The dark wedge on the upperwing of a Common Tern is most obvious in fall migration. 6 Unfortunately, the committee found no specimens of extended wings of Common Terns for comparisons. From below, Common Terns have a shorter, wider trailing edge to the outer five or six primaries. In Arctic Terns, this trailing edge is narrower and covers seven or eight primaries. Kaufman includes the following text regarding the dark trailing edge to the wing: Arctic Tern has narrow, sharply defined blackish tips to the outer seven or eight primaries; the effect is of a sharp, narrow black trailing edge to most of the outer part of the wing 7 and Common Tern has broader dark tips to the outer five or six primaries; the resulting dark trailing edge is broader than that of Arctic but not as long, and not quite so sharply demarcated. 8 The committee examined the underside of the primaries of the two Arctic Terns shown in Photos and and the dark trailing edge appeared to cover the outer seven primaries on each bird. Again, no specimens of Common Terns with extended wings were found for comparison, but the published literature is clear that the trail edge covers only five or six primaries on Common Terns. Photo : Note the even gray upperwing of adult Arctic Terns. 3 Sibley, page Dunne, page Kaufmann, page Kaufmann, pages Kaufman, page Kaufman, page 139 Page 20 of 45

21 Photo : Note the pearly white underwing (contrasting with the dark gray body) of adult Arctic Terns. Also, the dark edge to the outer primaries is shown Summary Members of the MD/DC Records Committee noted numerous differences between specimens of Arctic Terns and Common Terns. Some of these are well-documented and covered in most field guides and references. Others were a little more subtle and generally less discussed in the generally available literature. Perhaps most significant was the difference in the shade of gray between the two species. Arctic Terns were consistently a deeper pearly gray with a bluish tinge. Common Terns were more brownish gray, and sometimes slightly paler, particularly below. However, even the darkest Common Terns had a brownish tinge to the gray plumage above and below. Another noticeable mark was the contrast between the bright white undertail coverts and the rest of the underparts of Arctic Terns. Common Terns were much more uniform below, with the undertail coverts contrasting only slightly, if at all, with the rest of the underparts. In closing, Arctic Tern differs from Common Terns in the following ways: Pearly gray plumage overall, with a slight bluish tinge (Common Terns are gray washed with a distinct brownish tinge) Contrastingly white undertail coverts (the undertail coverts of Common Terns are washed with tan/gray and contrast less noticeably with the rest of the underparts) Long tail, usually extending beyond the tip of the wings (the tail of Common Terns fell more evenly with or fell short of the tip of the primaries on the folded wing) Short, straight bill (Common Terns appeared to have a longer, slightly down curved upper mandible) More rounded head meeting the bill at a sharper angle Page 21 of 45

22 Longer, narrower wings (more of each primary is exposed on the folded wing of Arctic Terns when compared with Common Terns) Adult Arctic Terns have an even, uniform gray wing above (Common Terns typically have a dark wedge on the upperside of the outer primaries) Adult Arctic Terns have a longer, narrower trailing edge to the outer 7 or 8 primaries below (the trailing edge on Common Terns only covers the outer 5 or 6 primaries) Photo : (left) and Photo (below) show an Arctic Tern tail and wing respectively. Note the evenly gray upperwing lacking a dark wedge References Dunn, Jon and Alderfer, Jonathan Complete Birds of North America, National Geographic. Dunne, Pete Pete Dunne s Essential Field Guide Companion, Houghton Mifflin Company. Kaufman, Kenn Field Guide to Advanced Birding, Houghton Mifflin Company. Olsen, Klaus Malling and Larsson, Hans Terns of Europe and North America, Princeton University Press. Pyle, Peter Identification Guide to North American Birds, Part II, Slate Creek Press. Sibley, David Allen The Sibley Guide to Birds, Alfred A. Knopf. Stokes, Donald and Lillian The Stokes Field Guide to Birds of North America, Little, Brown and Company. Page 22 of 45

23 3.3 Anna's/Ruby-throated/Black-chinned Hummingbirds Account by Tyler Bell Background. Maryland s second Anna s Hummingbird visited a feeder in Middletown, Frederick County, from 5 November until 9 December 2010, though it was only identified and banded on the final day of its stay. The first Anna s Hummingbird attended a feeder in Prince George s County in mid- November 2004 but was initially identified as a late Ruby-throated Hummingbird. There are two excellent field guides to North American hummingbirds available so this account does not recreate whole species accounts but rather focuses on a couple of identification criteria that should be readily visible on perched/feeding birds namely primary shapes. Photo : Members studying hummingbird skins. L-R: Mikey Lutmerding, Ron Gutberlet, Bill Hubick, Tyler Bell, and Joe Hanfman. Photo by Phil Davis Findings The committee studied trays of non-selasphorus hummingbirds including Black-chinned (Archilochus alexandi), Ruby-throated (Archilochus colubris), and Anna s Hummingbirds (Calypte anna). When comparing the birds side by side, Anna s stands out as larger whereas Ruby-throated and Black-chinned are similarly smaller (Photo ). Page 23 of 45

24 Photo : Overall Size - Male Black-chinned (above), Anna s (center) and Ruby-throated (below). Solitary birds will likely be less obvious so a small size difference, 3.5 inches versus 4.0 inches, may not stand out. However, close-up scope views or decent photos of a bird at a feeder should yield differences in the shape of the primaries which will be useful in separating these similar species. Photo shows the distinctive primary shapes of Black-chinned, Ruby-throated and Anna s, respectively. Photo : Primaries - Black-chinned (above), Ruby-throated (center), and Anna s (below). Page 24 of 45

25 Note that on Black-chinned the shape of the primaries is blunter, often referred to as shaped like a butter knife. The shape is somewhat similar to Anna s though the ninth and tenth primaries on Black-chinned are quite decurved. Ruby-throated primaries show an extreme angle and on many of the specimens, the inner primaries often show a slight outward flip toward the ends. Anna s primary shape tends toward more symmetrical across the vein, is similar in shape to Black-chinned but the outer primaries do not exhibit the same decurved shape. Also notice the consistent width of the Anna s primaries compared to the other two. Maryland s first Black-chinned Hummingbird is well overdue and separation from late Rubythroated Hummingbird will always be a problem. But, given today s photographic equipment, it s very likely that a perched, feeding bird can be identified to species without first necessitating capture. Page 25 of 45

26 3.4 Northern and Loggerhead Shrikes Account by Ron Gutberlet Background Given close views, the two species of shrike that occur in Maryland can be readily distinguished by bill size and shape; details of facial coloration; and head, body, and tail proportions. Nonetheless, recent discussions suggest that another traditional character coloration of the bill may not be as reliable as previously thought. A pale base to the lower mandible in Northern Shrikes (Lanius excubitor) as opposed to an entirely dark bill in Loggerhead Shrikes (L. ludovicianus) is depicted or mentioned in major field guides (e.g., Brinkley, 2007; Dunn and Alderfer, 2006; Sibley, 2000). While neither Sibley nor Dunn and Alderfer reference bill color in their text, their images clearly depict pale lower mandibles in all age classes of Northern Shrike, this feature is more pronounced in their depictions of younger birds (juvenile and 1st winter). The same authors show Loggerhead Shrikes with entirely dark bills (all ages, including juvenile, in Dunn and Alderfer; adult only in Sibley). Sibley shows a pale lower mandible in juvenile Loggerhead Shrikes, but none of the field guides cited depict a first-winter bird of this species. In contrast to these two guides, the photograph of an adult Northern Shrike in Brinkley shows an all-dark mandible, but the text next to the bill says, pale mandible. On 29 December 2010, Zach Baer found a shrike (Photo ) at Pickering Creek Audubon Sanctuary in Talbot County, Maryland. The bird, which only provided distant views during the initial observation, was identified as a Northern Shrike. Paleness of the lower mandible was a key consideration. Subsequent observations of the bird raised doubts about the initial identification, and Matt Hafner posted information to MDOsprey about a Loggerhead Shrike from New York (see blog post by David Sibley: that had generated extensive discussion on the ID-Frontiers listserver owing, in part, to a noticeably pale base to the lower mandible Findings We studied specimens of Loggerhead and Northern Shrikes from June, August, and September. None of these birds had a pale base to the lower mandible. Four adult Northern Shrikes collected during March, April, and May had completely dark bills. All immature Northern Shrikes that we examined exhibited an obvious pale base to the lower mandible. We also discussed differences in scapular color by age and species. Photo : Loggerhead Shrike (above) and Northern Shrike (below). Page 26 of 45

27 3.5 Carolina and Black-capped Chickadees Account by Mike Bowen Background The principal purpose of this skin study was to elucidate the factors that most definitively help a field observer distinguish between Carolina Chickadee (Poecile carolinensis) from Black-capped Chickadee (Poecile atricapillus). Note that the USNM records and skin labels reflect the earlier genus name, Parus, rather than Poecile. This will be evident in some of the photos. Photo : Members studying chickadee skins. L to R: Joe Hanfman, Gwen Brewer, Mike Bowen, and Walter Ellison. Photo by Phil Davis Findings Relative size: Black-capped Chickadees are generally noticeably larger than Carolinas, averaging perhaps ½ inch longer, and have longer tails (see Photo ), which compares a Carolina from Maryland with a Black-capped from Massachusetts. Also see Photos and , which compare a Carolina from Maryland with a Black-capped from Nova Scotia. Blackcapped Chickadees tend to be larger the farther north they breed, so the distinction between the two species in Photos and is particularly striking. Photo shows two Nova Scotia Black-capped, both large and chunky. A cautionary note: Carolinas vary in size, too, as is evident in Photo , which compares Carolinas from two nearby locations in Maryland. However, the larger bird here might be a Black-capped, incorrectly labeled as a Carolina. The ragged bib edge and large size is troubling. (Not that this contradicts the fact that some races of and individual Carolina Chickadees are larger than others. The species ranges widely, as far west as Oklahoma.) Amount of contrasting white in the wing coverts and secondaries: All the photos of Carolinas alongside Black-capped demonstrate that Black-caps virtually always have more contrasting white in the wings and coverts (see Photos , , and ). Carolinas too have contrasting white in the secondaries (see Photo ) but invariably it is less extensive than in Black-caps. The differences can be more subtle in the field, especially in poor light or distant views. Page 27 of 45

28 Interface between black of bib and white of upper breast: On Carolinas, this interface is a smooth line of demarcation; on Black-caps it is ragged and blotchy. This difference shows on all the photos accompanying this write-up. In addition, it is a feature that is relatively easy to gage in the field. White cheek patch: Both species of Chickadee have white cheek patches. However, on Carolina the patch gradually melds in color from white to gray as it reaches the nape and upper back. On Black-capped the white continues until stopping fairly abruptly at the nape, where it forms an area of quite sharp contrast between light and dark. See, for example, Photos , , , , and A corollary of this observation is that Black-capped cheeks can show (or appear to show) brighter white in the field than Carolina s. Buff color on flanks: Some field guides refer to this color as olive, but the color on all skins is more accurately described as buffy. Field guides note that Carolina has less of this color or perhaps a less intense version of this color -on the flanks, but examination of the USNM skins did not support this contention or at least did not support it sufficiently to make this a useful feature in the field (see Photos and ). The upper bird, a Carolina, in Photo appears to have about the same extent of buff (and about the same shade) as the Black-capped Chickadees in other photos, such as Photos , , and Summary: The three most reliable factors that can be used to distinguish these two species in the field are: (1) interface between bottom of black bib and breast -smooth in Carolina and ragged in Black-capped; (2) the way in which the rear of the light cheek patch merges with the nape and upper back feather--a white-gray gradation in Carolina and a much more abrupt lightdark transition in Black-capped; and (3) the greater amount of contrasting white edges on coverts, secondaries, and tertials of the Black-capped. The larger size of Black-capped and its longer tail are reasonably reliable factors, particularly with the larger (northern) races, but possibly not as reliable as (1), (2) and (3), above. Many of the Black-capped Chickadees seen by observers in the winter season have been noticeably larger than the Carolinas they were with (when direct comparisons were possible), which supports the notion that the irrupting Black-capped Chickadees are from states and provinces to our north rather than the Appalachian mountains of Maryland and Virginia to our west. Extent of and intensity of color on the flanks (variously described as olive or buffy) do not appear to be reliable factors that can distinguish between the two species. In the field, hearing the typical song and/or calls of one or the other species, together with specification of the factors above, should result in a correct identification, with the caveat that in zones of overlap between the respective breeding areas, birds of one species have been known to learn the vocalizations of the other. The account author notes that the help and insights offered by Walter Ellison were of great value in reaching the conclusions above. Page 28 of 45

29 Photo : Carolina Chickadees from Maryland. Note somewhat ragged bib of upper bird, more typical of Black-capped (or mislabeled?) Photo : Same two Maryland Carolina Chickadees as Photo Note large size of bird on right and its white-edged secondary feathers (a mislabeled Black-capped?) Page 29 of 45

30 Photo : Black-capped Chickadees from Cape Breton Island, Nova Scotia. Note large size, white feather edging. Photo : Same two Nova Scotia Black-capped Chickadees as Photo Note long tails, extent of white on cheek and rough-edged bibs Page 30 of 45

31 Photo : Black-capped Chickadee, Gaithersburg, Maryland, November 1975 (an irruption year) Note ragged lower bib, rather limited buff on flanks Photo : Black-capped Chickadee, Grantsville, MD (September - a presumed breeder). Note ragged bib edge, abrupt white-gray/black transition on rear of cheek patch, limited buff on flanks. Page 31 of 45

32 Photo : Carolina Chickadee from Maryland (above) and Black-capped Chickadee from Nova Scotia (below). Note larger size, longer tail of lower bird, white-gray/black contrast at rear of cheek patch (NS bird), rather similar amount of buff on flanks on both birds. Photo : Same two birds as Photo Note larger size, longer tail of lower bird (Black-capped, Nova Scotia), relatively small amount of white edges to secondaries on upper bird (Carolina, Maryland). Page 32 of 45

33 Photo : Same two birds as in Photo and Photo Note different ways in which color of cheek patch transitions towards nape and upper neck: gradual in Carolina (upper bird), more abrupt contrast in lower bird (Black-capped). Note larger size of lower bird. Page 33 of 45

34 3.6 "Black-backed" Robin (Turdus migratorius nigrideus) Account by Walter Ellison Background Three subspecies of American Robin occur on the eastern seaboard of North America: Turdus migratorius migratorius that ranges from central Quebec southward to southern Pennsylvania or north central Maryland and winters south into the southeastern United States; T. m. achrusterus that breeds from Maryland southward to northern Florida and winters in the southeast; and T. m. nigrideus, often known by the vernacular names black-backed or Newfoundland robin, that occurs in north central Quebec, Labrador south to the northeast shore of the Gulf of St. Lawrence, and insular Newfoundland (Pyle 1997, Godfrey 1986). The latter is apparently largely resident in eastern Canada, wintering in southern Quebec and the Maritime Provinces, and is regularly reported in New England. There are records of black-backed robin southward to northern Florida and westward to Illinois (Sallabanks & James 1999). It is likely that the blackbacked robin is also an uncommon but regular winter visitor to Maryland, particularly on the Coastal Plain Findings The following discussion of skins examined at the United States National Museum (USNM) is based on comparison of the single available specimen of T. m. nigrideus (Adult male, USNM , St. John s, NF, 20 July 2007, Photo ) to large series of the other eastern robin subspecies. As such nothing can be said about the range of variation of black-backed robin and comments herein represent generalizations from limited evidence. Also note that the bird was in worn late summer plumage and not in the fresher plumages expected in winter in Maryland. The most obvious difference between the black-backed and other eastern robins is the darkness of the upper back. The upper back feathers of the Newfoundland bird were broadly blackish-gray with very narrow pale fringes. The contrast with the dark crown was negligible (Photo ). The tail appears longer (not confirmed by measurement) than that of a specimen of southern robin (T. m. achrusterus, adult male, USNM , Mt. Mitchell, NC, 4 June 1930) and showed larger and whiter spots at the corners of the outer tail feathers (Photos , ). These differences are less pronounced in comparison to the common Maryland wintering subspecies migratorius (Pyle 1997). Differences in depth of the orange breast color were marginally useful, with nigrideus slightly darker than migratorius and achrusterus. It is doubtful that breast color would be of much use in the field. Other differences not mentioned in literature that we noted were the darker throat showing less extensive white with broader black streaks, and reduced white eye-arcs above and below the eyes (Photo ). These may be useful auxiliary characters in combination with the black upper back not contrasting with the nape but contrasting with the blue-gray rump, and the larger tail corner spots. These characters would not be as obvious in young males or might be absent in females, especially young ones. Therefore observers may be able to readily identify and document only adult males in Maryland. Page 34 of 45

35 Photo : Note relative tail length, and lack of contrast between nape and upper back in nigrideus. USNM , St. John s, NF, 20 July 2007 (above). T. m. achrusterus, USNM , Mt. Mitchell, NC, 4 June 1930 (below). Photo by Bill Hubick. Photo : Note coarser black throat streaks, slightly deeper orange breast, and prominent white spots at tail corners in nigrideus. USNM , St. John s, NF, 20 July 2007 (above). T. m. achrusterus, USNM , Mt. Mitchell, NC, 4 June 1930 (below). Photo by Bill Hubick. Page 35 of 45

36 3.6.3 Literature Cited Godfrey, W. E The Birds of Canada. National Museum of Natural Sciences, Ottawa. Pyle, P Identification guide to North American birds, Part I. Slate Creek Press, Bolinas, CA. Sallabanks, R., and F. C. James American Robin (Turdus migratorius). In The Birds of North America, No. 462 (A.Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA. Page 36 of 45

37 3.7 Variation between Pacific Wren and Winter Wren Account by Fred Shaffer Background General. In 2010, the American Ornithologists Union (AOU) voted to split Winter Wren into eastern and western species as part of the 51st supplement of the AOU Checklist. Traditionally, Winter Wren (Troglodytes troglodytes) had been divided into three major subspecies groups in North America: the eastern hiemalis group, the western pacificus group, and the alascensis group of the Aleutian Islands and Bering Sea area. The extent and frequency of vagrancy of the newly created species has yet to be determined. Eastern birds (Winter Wrens) have been found west to California. However, records of western vagrants (Pacific Wrens) to the east are not well documented and further research is needed to determine the extent to which Pacific Wrens stray to the east of their currently known range. Taxonomy. The MD/DCRC officially follows the AOU in terms of taxonomy. The 2010 AOU decision regarding Winter Wren produced two species of interest to North American birders; the eastern Winter Wren (Troglodytes hiemalis) and the western Pacific Wren (Troglodytes pacificus). Winter Wren consists of two subspecies: subspecies pullus in the Appalachian Mountains from West Virginia to Georgia; and the more widespread subspecies hiemalis. The Pacific Wren consists of seven subspecies broken into two main groups; the Western Group and the Alaska Island Group. There is much variation between the two groups, with the Western Group being significantly smaller and darker than the relatively large and uniformly pale brown Alaska Island Group. This account focuses on differences between the Winter Wren and western group of Pacific Wrens due to their similarities in size, structure and plumage and the increased possibility, at least theoretically, that the western group of Pacific Wren might stray into Maryland Findings Overview: At the February 2011 Skins Workshop of the Maryland/DC Records Committee, specimens of both Winter Wren and Pacific Wren were examined. More specifically, the committee examined a tray of Winter Wrens from Maryland, and several trays of Pacific Wrens from the west coast (predominately Washington state). A variety of differences were noted between the two species, some of which should be readily observable, while other differences were more subtle and probably more difficult to judge under field conditions. Page 37 of 45

38 General Differences and Distinguishing Field Marks: First, it was noted that Winter Wren appeared to show some variation over its eastern range, with birds from Georgia being slightly darker and more colorful below than the more northerly birds from Maryland. Although there was overlap, specimens from the Georgia tray were consistently darker below than the specimens from Maryland that the committee examined side by side. The Maryland birds appeared to be a more uniform medium brown below, while the Georgia specimens were darker below, with the belly being noticeably darker than the throat and upper breast. Not only were the Georgia specimens darker below, but they appeared to have a richer, almost chestnut wash to the throat and a darker brown/gray belly. The Maryland birds appeared more uniform below, lacking the more noticeable contrast between the throat and the belly. See Photo which captures this subtle difference between the Georgia specimens (above) and the Maryland specimens (below). These differences may reflect the variation between the widespread subspecies hiemalis and the subspecies pullus, which is generally confined to the central and southern Appalachians. While little readily available published material is available about subspecies pullus, Raymond A. Paynter, Jr. notes that it is barely distinguishable from hiemalis, but that specimens from Tennessee, Virginia, and North Carolina show that subspecies pullus is almost constantly, slightly darker than birds of the northern race collected in the same season. 9 This is consistent with the observations from the 2011 Skins Workshop. Photo : Specimens from Georgia (top row) appeared to be subtly darker below than the more northerly Maryland birds (bottom row), especially on the belly. This illustrates one of the apparent differences between Winter Wren subspecies hiemalis and pullus. 9 Paynter, Jr., Raymond A. Taxonomic Notes on the New World Forms of Troglodytes. Page 38 of 45

39 Photo : Winter Wren specimens from Maryland. Photo : Pacific Wren specimens from Washington State. Page 39 of 45

40 How does the Pacific Wren differ from Winter Wren? The committee mainly focused on the differences between Pacific Wrens and Winter Wrens from Maryland and several subtle differences were noted. Pacific Wrens were a deeper rufous brown on the breast and throat then Winter Wrens. Whereas the Winter Wrens were more uniformly light tan on the breast and throat (sometimes included a very pale, almost off-white throat), Pacific Wrens were consistently darker and more colorful on the throat and upper breast (see Photo ). Photos and show close-up views of the underparts of both species, which highlight the subtle differences in color, tone, and pattern. Photo : Underparts of four Winter Wrens. Note the more uniform brown color of the throat and breast, as well as the neatly patterned belly and undertail coverts. Photo : Note the slightly darker, rustier throat and breast of these three Pacific Wrens, contrasting less with the pattern of the belly and undertail coverts than on Winter Wren Pacific Wrens seemed more messily mottled with dark gray on the lower belly and undertail coverts (see Photos and ). This gave them an appearance of being fairly dark in the region, but messy. Winter Wrens appeared to be more neatly patterned in the flanks 10, lower belly and undertail coverts, with alternating light brown and dark brown barring (see Photos and ). The end result was that both species appeared fairly dark in this part of their plumage; but Winter Wrens had a neat barring pattern here, while Pacific Wrens appeared more unevenly dark and mottled. This may be partly due to the placement of 10 Sibley, page 387. Page 40 of 45

41 the feathers and the condition of the specimens, but this difference was noticeable on the majority of specimens viewed. Pacific Wrens were darker brown above, more of a chocolate brown than the rusty or rufous brown of the Winter Wren. While the Pacific Wrens had a deep, dark brown appearance, the Winter Wrens had a definite rusty tone to their upperparts. David Sibley notes that Pacific Wrens are a uniform color above with little or no barring, but that Winter Wrens are usually more mottled and barred with dark and white. 11 The most obvious of these markings are distinct white dots which contrasted strongly with the otherwise dark back. (See the second bird from the left in Photo ) Photo : Note the subtle color difference between the two Winter Wrens (left two) and the two Pacific Wrens (right two). The Winter Wrens have a rusty wash to the brown upperparts, while the Pacific Wrens appeared to be a deeper, chocolate brown lacking the rusty tones. Pacific Wrens had much smaller tan spots on the edge of the primaries. Winter Wren had similar but much larger tan spots in this area, which was seen as the leading edge of the folded wing on the specimens. Photos and show the difference in the size of the spots between the two species. David Sibley further notes that the spots on the Pacific Wren are darker and more brown on average, while Winter Wren are a paler off-white, though he qualifies that this is rather subjective and difficult to judge. 12 However, this color difference also appears to be evident between the two species in Photos and Sibley, 12 Sibley, Page 41 of 45

42 Photo : Note the small tan spots on the greater coverts of the Pacific Wren. Photo : Note the much larger tan dots on the greater coverts of the Winter Wren. Page 42 of 45

43 Pacific Wrens were consistently more even colored on the throat, breast, and upper belly. They were the same rusty brown on the throat, breast, and upper belly, with no part of this plumage appearing lighter or darker than the rest (see Photos and ). However, Winter Wrens showed more variation, often being palest around or slightly below the center of the belly. In addition to being a paler brown lacking the ruddy tones, they also often had paler areas on the belly or center of the throat (see Photos and ). Photo : Note the differences above in the color and tone of the throat and breast of the Winter Wren (left) and Pacific Wren (right) Conclusions The 2010 split of the Winter Wren into Eastern and Western Species will undoubtedly lead to increased scrutiny of the two species across North America. The pattern of vagrancy of Pacific Wrens has not been well documented and there is much to learn about the occurrence of Pacific Wrens in the east, if in fact it occurs at all. Similarly, many of the known field marks separating the two newly created species need to be field tested. Many field marks are not readily noticed under field conditions or are subjective, and may need refinement as additional information is gathered. However, as Winter Wrens (ssp. hiemalis) have been documented west to California, it seems plausible that Pacific Wrens could occur to the east of their known range. Hopefully, the field marks will be refined and a better understanding will be gained of the pattern of vagrancy of the newly created Pacific Wren in the coming years as additional research is done and field observations are made. Page 43 of 45

44 3.7.4 Literature Cited Alderfer, Jonathan (editor) Complete Birds of North America, National Geographic Society. Paynter, Raymond A Taxonomic Notes of the New World Forms of Troglodytes. Museum of Comparative Zoology. Sibley, David Allen The Sibley Guide to Birds. Alfred A. Knopf, Inc. Sibley, David Allen (posted August 13th, 2010; last edited February 18th, 2011) Stokes, Don and Lillian The Stokes Field Guide to the Birds of North America. Little, Brown and Company. Photo : Pacific Wren (above) with Winter Wren (below). Page 44 of 45

45 4. Adjournment The workshop ended at approximately 3:00 pm. Photo 4-1. Members taking a lunch break in the Richmond Library. Clockwise: Gwen Brewer, Mikey Lutmerding, Paul O'Brien, Rob Gutberlet, Tyler Bell, Walter Ellison, Nancy Martin, Fred Shaffer, Mike Bowen, Joe Hanfman, and Bill Hubick. Photo by Phil Davis. 5. Acknowledgements Many thanks to the species account authors. Special thanks to Roger Clapp, our USNM sponsor, for again hosting us. Respectfully submitted, Bill Hubick, Chair Pasadena, MD bill_hubick@yahoo.com Phil Davis, Secretary Davidsonville, MD pdavis@ix.netcom.com 21 Mar 2012 Page 45 of 45