ML378270731

Age

Not specified

Sex

Not specified

Media notes

Dusky Warbler initially found on 9 October 2021 by Jon Fisher and Sarah Ngo, here photographed by Curtis A. Marantz on 12 October 2021 along Woodley Creek in the Sepulveda Basin Recreation Area, Van Nuys, Los Angeles County, Califorhia.

Observation details

This bird was initially found in the morning on 9 October 2021 on by Jon Fisher and Sarah Ngo, after which many others saw it later the same day and in the two days prior to my visit this afternoon. Others had the bird in view when I arrived, so I was able to see it within five minutes of my arrival, and then many times thereafter, given that we saw the bird intermittently over a period of almost three hours before I departed the site about an hour before sunset. The warbler was most easily seen foraging on the paths on either side of the creek when it hopped on the ground in the shade of the Russian Thistles (Kali tragus) that were growing along the paths. When flushed the warbler would also fly into the river channel, in which it usually vanished quickly amid the impenetrable mass of sunflowers (presumably Helianthus sp.) and other annual shrubs, occasionally perching in the open momentarily atop the stalks but more often dropping into the middle of the vegetation. This bird was nevertheless relatively easily seen over extended periods of time as it moved right along the ground at edge of the vegetation or occasionally in the middle of the patch, but almost always in the shade and only occasionally moving rapidly through the sunlit patches. The easiest way to locate the warbler was when it called, giving a dry “tick” call that to me sounded much like the “chip” call of a Lincoln’s Sparrow (Melospiza lincolnii) in both its amplitude and overall quality. This said, the bird was generally silent when foraging, only calling when flushed or during interactions with other birds. This bird was moderately aggressive, in that I repeatedly saw it chasing other birds, including Common Yellowthroats (Geothlypis trichas), Lesser Goldfinches (Spinus psaltria), and possibly even the larger House Finches (Haemorhous mexicanus). This was a small, warbler-like bird that looked and behaved somewhat differently than a parulid warbler despite an overall similarity. The bill was slim throughout its length and tapering to a pointed tip along a culmen that appeared to be straight nearly to the tip, where it curved downward slightly, and short, in that it would have extended backward on the face to a point near the rear edge of the eye. The forehead was weakly sloping and the crown was gently rounded on a head that may have been larger in proportion to the body than those of most parulid warblers. I further thought the neck was short and relatively stout, and that the body was conspicuously plump and seemingly more full-chested than pot-bellied. The medium-length wings had a primary projection that was between one-third and one-half the length of the exposed secondaries, ad in which I saw the tips of quite a few primaries extending beyond the longest secondary, but I was unable to count them. I further thought the tapered wingtip reached right about to the tips of the uppertail coverts, but my impression was that it fell somewhat short of the tips of the undertail coverts, which appeared to be relatively long. The tail seemed shorter than those of most North American Warblers, in that it was only about as long as the body without the head or neck; it also appeared to be parallel-sided and jagged at the tip, but the precise shape was difficult to determine. The legs were of unremarkable mass for a small bird, but they may have been a bit longer than those of some arboreal parulids. This bird was a relatively warm, brownish color overall. I thought the forehead and crown were dark brown with a warm cast, but without appearing at all reddish, and lacking internal markings. Demarcating the dark cap rather sharply with a well-defined supercilium that extended through the supraloral region, over the eye, and back along the upper edge of the auriculars to their rear edge, and seemingly a short distance beyond, curving upward at its terminus to pinch off subtly the rear edge of the dark cap. The supercilium appeared to be buffy throughout, and not any more richly colored before the eye. Further demarcating the lower edge of the supercilium was a dark brown eyeline that appeared to extend form the base of the bill to the eye, and then behind the eye along the upper edge of the auriculars to their rear terminus. The eyeline was at least as dark as the cap, if not somewhat darker, it appeared to be brown rather than blackish, and it was about as deep as the eye was wide, though maybe a bit broader behind the eye than before. Complementing the supercilium, but seemingly more whitish was a narrow, but well-defined crescent under the eye. Between the supercilium and the crescent below the eye, I did not think the eyeline extended either above or below the eye. My impression was that the lower part of the face and the auriculars below the dark eyeline were a dingy buff color that was not unlike the color of the supercilium, and I did not notice either a dark rear edge to the auriculars or any obvious internal markings. I nevertheless thought the throat was a paler buff than the sides of the face, but with the two colors blending into one another without a sharp contrast. The underparts appeared to be a dingy-buff throughout, though maybe more brownish at the sides of the breast and along the flanks, and a duller and paler buff on the belly. I thought the undertail coverts were again a rather rich buff in color, and without obvious markings. I did not see the underside of the tail all that well, but it appeared to be dark brown and lacking obvious markings. The upperparts were a warm, dark brown color almost throughout. I thought the back and maybe also the sides of the neck were about the same shade of dark brown as the cap, but the sides in particular may have been paler and more buffy. The back and scapulars were indeed about the same shade of warm, dark brown as the cap, and they likewise appeared to lack any markings. I did not see any obvious contrast between the secondary coverts and the back and scapulars, but I suppose I could have missed a subtle contrast. Both the alula and associated feathers, and the primary coverts contrasted as darker markings along the leading edge of the closed wing even though close inspection seemed to suggest that the primary coverts were edged with a warmer and maybe even slightly reddish shade of brown that contrasted with the darker and colder brown alula and tips of the feathers, which resulted in an obvious demarcation of the bases of the primary coverts and similarly patterned primaries by a darker band that represented the tips of the primary coverts. The innermost secondaries were a relatively cold, dark brown color that contrasted weakly with what appeared to be subtly lighter and warmer edges that were poorly defined, but on the remaining remiges, the dark brown centers contrasted rather conspicuously with narrow but well-defined edges of a warmer and possibly slightly more reddish brown to create a finely striped pattern that appeared similar on the primaries and secondaries. I further thought the exposed primary tips were largely the same dark brown that characterized the inner webs of remaining remiges, and I did not see obviously paler fringed that would have facilitated my counting the exposed primary tips. I did not see the rump clearly, and my impression of the upperside of the tail was only that it was dark brown and not obviously different in color or pattern from the remiges; however, I did not specifically see whether the rectrices were fringed paler. I thought the bill was mostly dark, but the lower mandible was conspicuously paler and seemingly fleshy across about the basal half. The eyes were certainly dark, but I never did notice in the field any obvious brown tones. The legs were a dusky flesh in color, possibly appearing lighter and more flesh-colored when seen from behind, but this may also have reflected the light conditions. I think the feet were similar in color to the legs.

Technical information

Model

Canon EOS 7D Mark II

Lens

EF100-400mm f/4.5-5.6L IS II USM

ISO

800

Focal length

400 mm

Flash

Flash did not fire

f-stop

f/6.3

Shutter speed

1/125 sec

Dimensions

3376 pixels x 2135 pixels

Original file size

9.4 MB