Chestnut-sided Warblers in song: more than meets the ear

This is a re-upload of an article I wrote in 2016: Birdsong is a fascinating study subject and living in this ‘day and age’ when one can step outside, record a bird in song with their smartphone, step back inside, upload the recording to their computer and analyze the recording via spectrograms (such as those outputted on xenocanto) = simply amazing. Continue reading Chestnut-sided Warblers in song: more than meets the ear

ID: Juvenile Lincoln’s vs. Swamp Sparrow

Identification of juvenile Lincoln’s Sparrow

Head: On Lincoln’s, the crown detail is especially important. The crown is wholly brown to buffy-brown with distinct black streaking throughout. The median crown stripe is poorly-defined, and blends into the lateral crown stripes; the lateral crown stripes are greyish and finely marked with dark brown/blackish streaking. The edge to the upper portion of the supercilium averages more weakly defined than on Swamp Sparrow. The moustachial and malar stripes appear, on average, less distinct, and slightly narrower compared to Swamp. The throat is often lightly streaked, especially along its edges. In its entirety, the head detail of a Lincoln’s Sparrow is quite muted overall compared to that of Swamp. There are less blackish tones throughout, and less sharply defined edges.

The bird in its entirety: In my opinion, second-rung behind head detail. Lincoln’s appear more muted in colour, overall. They have less sharply-defined edges throughout the head; have less blackish (more brownish) detailing throughout, and average slightly duller chestnut edging throughout the flight feathers.

Bill: Regardless of morphometric measurements, the importance for here is field applicability: is the difference perceptible? Photo after photo, the bill of a Lincoln’s is perceptibly more delicate in build compared to Swamp. The bill averages slightly lighter in build, being more slender and narrow, and sometimes appears shorter; when viewing the ‘face’ in its entirety, this sets off a “cuter” expression.

Greater coverts: Next in rung, in terms of field-applicability, is a look at the greater coverts. In Lincoln’s, each greater covert feather is dark, mainly blackish, with buff edging. This contrast averages slightly duller than the black-centred, bright buff edging seen with Swamp Sparrows. Note that this detail could be extremely difficult to correctly interpret without the use of photos of the specimen to examine once back home from the field.

Underpart streaking: Lincoln’s average more heavily-streaked throughout the underside, especially along the sides of the breast and just below the edges of the chin, where dense streaks rain down upon a buffy bloom to the entire chest. There is a surprising degree of overlap in this feature, however, so it’s not at all bulletproof. Does the streaking to the underside of Lincoln’s average slightly more extensive, marginally crisper, somewhat lighter in colour (lighter brown) than Swamp? I believe so, but these are averages, not absolutes.

Legs and feet: After reviewing hundreds of photos of both species, I couldn’t help but notice that the tarsi and feet of Lincoln’s Sparrows are daintier in build compared to Swamp. I’m not sure if this is described in the literature? Perhaps it’s an old hat field impression.

Buffy “bib”: This is a shared characteristic of juveniles of both species. My assumption is Lincoln’s are more likely to show consistency in this feature; Swamp possibly less likely. I wouldn’t give it much weight. It’s easy to see the classic adult Lincoln’s-buff in a juvenile bird, but know that it’s a shared character between the two species.

Photographs

Figure 1: Crown detail. Juvenile Lincoln’s Sparrow, Embrun Sewage Lagoons, Embrun, Ontario. 23 July 2017.

Figure 2: Crown detail. Juvenile Lincoln’s Sparrow, Embrun Sewage Lagoons, Embrun, Ontario. 23 July 2017.

Figure 3: Overall bird detail, juvenile Lincoln’s at left; juvenile Swamp at right. At left photographed at the Embrun Sewage Lagoons, Embrun, Ontario on 23 July 2017; at right, at the Nonquon Sewage Lagoons in Port Perry, Ontario on 21 July 2017. Copyright Wayne Renaud. Note also in this photo the delicate build of the legs and feet of the Lincoln’s in direct comparison to the Swamp (relative size difference between birds in photos was manipulated by eyeballing, so therefore it is not exact)

Figure 4: Overall bird detail, juvenile Lincoln’s at left; juvenile Swamp at right. At left photographed at the Embrun Sewage Lagoons, Embrun, Ontario on 23 July 2017; at right, in St. John’s, Newfoundland, on 22 July 2017. Copyright Frank King. Note also in this photo the delicate build of the legs and feet of the Lincoln’s in direct comparison to the Swamp (relative size difference between birds in photos was manipulated by eyeballing, so therefore it is not exact)

Figure 5: Overall bird detail, juvenile Lincoln’s at left; juvenile Swamp at right. At left photographed at the Embrun Sewage Lagoons, Embrun, Ontario on 23 July 2017. At right photographed in St. John’s, Newfoundland, on 22 July 2017. Copyright Frank King. Note also in this photo the delicate build of the legs and feet of the Lincoln’s in direct comparison to the Swamp (relative size difference between birds in photos was manipulated by eyeballing, so therefore it is not exact)

Figure 6: Bill detail. Juvenile Lincoln’s Sparrow, Embrun Sewage Lagoons, Embrun, Ontario. 23 July 2017.

Figure 7: Bill detail. Juvenile Lincoln’s Sparrow, Embrun Sewage Lagoons, Embrun, Ontario. 23 July 2017.

Figure 8: Greater covert detail. Juvenile Lincoln’s Sparrow, Embrun Sewage Lagoons, Embrun, Ontario. 23 July 2017.

Closing comments

Separating juvenile Lincoln’s from Swamp is challenging and requires a multi-character analysis of plumage detail. Hopefully, this ID guide proves to be helpful to those looking to separate the two species!

Acknowledgements

Thank you to Wayne Renaud and Frank King for the use of their photos of juvenile Swamp Sparrows.

Recommended Reading/Reference List

Migration Research Foundation, McGill University: http://www.migrationresearch.org/mbo/id/lisp.html

Pyle, P. 1997. Identification guide to North American Birds. 2nd printing. Part I, Columbidae to Plocidae. Slate Creek Press, Bolinas CA.

Rimmer, C.C. 1986. Identification of juvenile Lincoln’s and Swamp Sparrows. Journal of Field Ornithology 57: 114-125. https://sora.unm.edu/sites/default/files/journals/jfo/v057n02/p0114-p0125.pdf.

Sibley, D.A. 2014. The Sibley Guide to Birds. 2nd ed. New York: Alfred A. Knopf.

Western Meadowlark Field Mark Checklist

Western Meadowlark Field Mark Checklist

In Winter (Basic) Plumage

Head Detail

  • Head detail in winter Western Meadowlark (WEME) is key. The lateral crown stripes and post-ocular wedge are typically medium-brown, which contributes to weakened contrast with the adjacent areas of the head. In Eastern Meadowlark (EAME), the lateral crown stripes and post-ocular wedge are quite blackish; this colouration draws forth strong contrast with the adjacent areas of the head.

Body Detail

  • Overall, a basic plumage WEME is washed-out and “sandy” in appearance. The edging to the feather tracts throughout the upperparts is less rufous, as in EAME, and more “sandy” and cold-toned. EAME is notably higher in contrast, with stronger saturation to the plumage, showcasing higher contrast between the various feather tracts (head and body detail) than on WEME.
  • The base colouration to the greater coverts, folded secondaries and tertials is pale and more greyish in WEME, and typically is darker and warmer brown in EAME.
  • The greater coverts and folded secondaries and tertials on a WEME showcase thin, parallel-sided blackish barring on a pale base colour. On these same feather tracks, thick confluent blackish barring occurs on EAME, overtop a darker brown base colouration. The net result is a darker wing fold.
  • The flanks and undertail coverts (UTC) are paler and greyer on WEME and buffier on EAME.
  • WEME are longer winged than EAME.

Tail Detail

  • On WEME, the central tail feathers show free, parallel-sided blackish bars on a pale background. On EAME, the bars widen toward the rachis and become confluent with adjoining bars, along the mid-vein. Thus, the tail feathers appear dark with deep pale notches along the fringes on EAME (Jaramillo and Burke 1999).
  • WEME typically has less white in the tail than on EAME; however, there appears to be some overlap in this feature (Jaramillo and Burke 1999). Look for the amount of dark on R4 (third from the outside) and the outer two rectrices (R5 and R6). WEME tends to have a mostly dark R4 and noticeable dark terminal shaft streaks on R5 and R6 (Jaramillo and Burke 1999).

Photos

Photo: Western Meadowlark in Napanee, Lennox & Addington County. 25 January 2022. Luke Berg.

Photo: Western Meadowlark in Napanee, Lennox & Addington County. 25 January 2022. Luke Berg.

Photo: Western Meadowlark in Napanee, Lennox & Addington County. 25 January 2022. Luke Berg.

Photo: Eastern Meadowlark near Point Petre, Prince Edward County. 25 January 2022. Luke Berg.

Photo: Eastern Meadowlark near Point Petre, Prince Edward County. 25 January 2022. Luke Berg.

Acknowledgements

Thank you to Luke Berg for granting permission to use his photos in this document. Luke photographed both species of meadowlarks within several hours on a sunny day, availing an Apples-to-Apples comparison of features. Thank you to Brandon Holden for all previous discussions on the intricacies and challenges of meadowlark ID.

References

Jaramillo, A., and P. Burke (1999). New World Blackbirds: The Icterids. Princeton University Press, Princeton, NJ, USA.

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Click here for a PDF copy of the Western Meadowlark Field Mark Checklist web article

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Jon P. Ruddy

eontbird@gmail.com

26 January 2022 

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