ML617551209
large shorebird sp. Scolopacidae sp. (large shorebird sp.)
Contributor
Date
Location
- Age
- Not specified
- Sex
- Not specified
Media notes
The possible Red Knot is immediately above the Greater Yellowlegs near the center of the photo. It is at the left end of a line of birds extending to the right. Only three of these birds show the side of their heads and their bills. There is the mystery bird, above the Greater Yellowlegs, and what I take to be two Stilt Sandpipers. Their long, decurved bills fit, and they seem to have a rufous stripe across their face, below a light supercilium, and descending towards the rear of the head. Both are much darker below than the mystery bird. Since Dunlin were in the pond also, I worried at first about these being Dunlins with the dark bellies of breeding plumage birds. Possible, I suppose, but Dunlin is more plain-faced, especially in breeding plumage, without a strong stripe through the face.
Observation details
This is a pro and con report, in two parts. First, a case for an ID for the Mystery Bird in the photo is given (exact location of the bird in the photo is described below). This ID is Red Knot. Second, similar species are considered for comparison and a case is given against Red Knot. In the end, the question of the ID of the Mystery Bird is left open. None of the 12 options considered seems to be a really good fit. A mystery indeed! The subject of this report is a larger shorebird, approximately the same length as two nearby birds that appear to be Stilt Sandpipers, but with a heavier build, a larger head, and, most notably, a much shorter, straighter bill than Stilt Sandpiper. These features at least suggest Red Knot. The bird's location in the photo is above the Greater Yellowlegs that is the largest bird in the photo. I call the bird in question the Mystery Bird. If more about its location is desired, it is at the left end of the tightly-bunched group of ca. 7 shorebirds at the top of the photo, the central part of the top. The question I asked myself is, are there any shorebirds of this approximate size, ca. 9.5 inches long (the Sibley length of a Stilt Sandpiper), that have a bill as straight and proportionally short as the 10.5" Red Knot? I couldn't come up with one at first, but after more thorough consideration of the case, I could. Hence, the two parts of this report. My photo documentation is unfortunately not sharp. But the question I'm posing is about structure, not about details of plumage. The key points are the size of the bird in comparison with the nearby Stilt Sandpipers, and the length and shape of the bill in proportion to the size of the bird. The photo may be good enough for judgment on these two points. To be sure, Red Knot would be much more expected on the coast. For example, it appears not to be present on the Sugar House Pond or Estero Llano Grande bar charts. But it has been reported inland in the Valley, for example, two years ago at Tiocano Lake, about 5 mi. away from Sugar House Pond. Granted, that was a 9/3 report, without a photo. But the date is not a problem. Indeed, Red Knot is more common in fall rather than spring migration. Red Knot has also been reported inland in Hidalgo County, many times in 2022, with at least some photos, at Delta Lake (from Nov-Dec). Let's get some comparative lengths of mostly relatively short-billed shorebirds on the table (all from Sibley 2nd ed.) as a prelude to considering other possible answers to the question of the identity of the Mystery Bird. The lengths considered are from 8" to 12". An asterisk after the name indicates that the species was reported on eBird at the Sugar House Pond on the same day I was there, on 4/14/24. The first two are not short-billed shorebirds, but are included to provide size comparisons. Except for the last two, all were reported from the Sugar House Pond on 4/14/24. Stilt Sandpiper* 9.5" (included because it is taken as essential for size comparison with the mystery bird in this photo, not because it is short-billed or straight-billed) Dunlin* 8.5" (also included for size comparison, not because it is short-billed or straight-billed) Pectoral Sandpiper* 8.75" (ruled out because mystery bird does not have sharp demarcation between dark and light areas near the line between breast and belly) Wilson's Phalarope* 9.25" (ruled out because of its overall whiteness, thinner bill, smaller head) American Golden-Plover* 10.5" (ruled out because its bill is too short, and there is no clear contrast between dark cap and light supercilium in the mystery bird in the photo.) Upland Sandpiper* 12" (ruled out because no long neck, small head, and long tail on Mystery Bird.) Buff-breasted Sandpiper* 8.25" (ruled out because its face is too pale and bill is too short and thin; even given the poor quality of the photo, one should be able to make out buff tones if the bird were BBSA.) Sanderling* 8" (ruled out because Sanderling is too gray above in basic plumage, not brown; in alternate plumage breast would appear dark at this distance, perhaps with some rusty tones showing) Lesser Yellowlegs* 10.5" (ruled out because its head is too small, bill a little too long, and build slight rather than heavy -- photo provides a direct comparison of the LEYE and the mystery bird: jizz does not match.j Black-bellied Plover* 11.5" (ruled out obviously in the case of its alternate plumage; for basic plumage, size and bill are problematic: a BBPL should be clearly longer than nearby Stilt Sandpiper and its bill should be a bit shorter and thicker. The upper parts should be more gray than brown.) Ruff 9" (ruled out because Ruff has a longer neck, and the neck and breast should show "blotchy black" at this time of year (Sibley, 2nd ). Usually, it has orange legs. If it did, there would be at least some hint of color on the legs in the photo.) Red Knot 10.5" Having gone through this list, after having given some basic points in favor of the ID of Red Knot for the Mystery Bird, are there any potential problems with such an identification? Yes, there are. Here are a few: measurements of the Mystery Bird and the Stilt Sandpiper in the photo show the former to be a bit shorter than the latter. This is not what would be expected if Red Knot were the correct ID, given the measurements above of the Red Knot and Stilt Sandpiper, 10.5" and 9.5", respectively. Of course, my rough and ready photo measurement is not the measurement of an ornithologist in a lab, working with specimens. But it is worrisome. Also, the bill of the Mystery Bird appears slightly decurved rather than simply straight. Another issue: Is the Mystery Bird short-legged, as a Red Knot should be? Compare with the Stilt Sandpiper: unless the depths they are in are different, the Mystery Bird seems to have legs as long or longer than those of the Stilt Sandpiper. Other details: on a Red Knot we should see more of an eyeline; the color should be more gray above than brown; and in alternate plumage, the breast would be darker rather than light, as in the photographic image of the Mystery Bird. Well, that concludes the con part of the report. Any other possibilities or counter-arguments?
Additional species
Technical information
- Model
- DC-G9
- ISO
- 200
- Focal length
- 400 mm
- Flash
- Flash did not fire
- f-stop
- f/6.3
- Shutter speed
- 1/1600 sec
- Dimensions
- 3270 pixels x 1839 pixels
- Original file size
- 1.03 MB