投稿者
日付
場所
- 年齢
- 指定なし
- 性別
- 指定なし
観察結果の詳細
Initially noticed perched on power lines with other common swallows. I first noticed the overall buffy underside and buff forehead. The bird then started to fly around and I was able to get more shots of the upper and under parts with the buffy throat extending into the breast ruling out cliff swallow. Photos to follow. Justification for Caribbean sub-species designation is taken from the Sibley publication in 2021 (https://www.sibleyguides.com/2021/04/new-illustrations-of-cave-swallow-subspecies/#:~:text=Mexican%20(or%20Texas)%20subspecies%20%E2%80%93%20paler%20individual&text=Birds%20like%20this%20are%20fairly,once%20in%20the%20same%20individual.) The key features identifiable in the Somass estuary bird are: The rump color, which appears darker and more saturated than any of the other orange body plumage. Mexican subspecies tend to show a uniform orange color with the rump usually notably sandy-looking. Sibley suggests that this is the most reliable feature for separating the subspecies. The flank streaking also fits for the Caribbean, with obvious dark rufous streaks, instead of streaking that is low contrast/bleeds into other body feathers, as seen in the Mexican sub-species. Cheek color - this bird, like other individuals identified as Caribbean, averages darker, and also averages less uniform, with a band below the eyes to the chin often distinctly paler than the rear cheeks. Additionally, the Caribbean birds appear to be significantly smaller on average than other subspecies. This is obviously a difficult criterion to determine; however, I did note that this bird looked particularly small in comparison to the other swallow species present at the time. I have added extra photos that show the CASW next to a VGSW. I don't know how much value this really adds, as the angle and other factors make it difficult to be confident in comparing the two birds. Though, to my eye, the tail of the VGSW does appear a bit longer. It is also interesting to note that the observations of Caribbean cave swallows in the northeastern US were also spring finds, with some suggestion that this is more expected compared to the fall records, which seem to exclusively be of Mexican birds. This size variation and rump color variation are also supported by Pyle Volume 1 Version 1, though I have not been able to check if further detail has been added in version 2 of this publication.
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