ML249360931
Double-crested x Neotropic Cormorant (hybrid) Nannopterum auritum x brasilianum
作者
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- 年龄
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观察细节
An apparent second-year cormorant on the island in Pond 1 showed several features of a young Neotropic Cormorant (NECO), but also some characteristics that were better for Double-crested. As I was able to later see photos of a bird that Tom Wurster found here about 3 months ago (12 April, 2020), that was ultimately thought by several to be a NECO X DCCO hybrid, it is quite possible (or probable?) this bird on 10 July, 2020, is the same individual. After studying the bird for the last ~1.5 hours of light (and taking a about 60 photos, but unfortunately in fading light), I spent a few evenings researching as much as I could on ID of NECOs (especially looking to see what variability they might show, where the species is more common). Also reached out to a few other local birders who have more experience with the species than me, Ended up, as with the others, thinking the bird possibly best fits a hybrid Neotropic X Double-crested. Features of the bird that best fit NECO would be: 1) it's small size. This was quite pronounced when close to the DCCOs (of which about a dozen where loafing on the island in fairly close proximity to the "NECO type"). It appeared pretty close to the relative size one would expect for a Neotropic. 2) The angle of the "gular pouch", at the gape, always looked to be acute (or less than 90-degrees). 3) The tail appeared relatively long, versus that of DCCO. An intermediate feature or one better for DCCO was the light, buffy-yellow color extending above the gape, and in some of the photos, into the lores as well. However, the photos that seem to show this light yellowish color the most are the ones taken during the last rays of the setting sun, when everything had an exaggerated "yellow glow". Even the intensity of the gular pouch's yellow was twice that vs. yellow shown in photos taken when the bird was first seen (about 6:20pm). So my feeling is the lores especially were a creamy color or buffy (at most a pale, yellowish-buff), though a light yellow did seem to extend along the fleshy area on the upper basal area of the gape. The yellow of the gular area was mostly restricted to the proximal portion and paled out to a pale creamy (or yellowish-buff) distally. There was the same (yellowish-buff) coloration extending around the eye, which from some accounts I read might be more typical of DCCOs. The relative bill length I'm not too sure on. It didn't seem to be on the relatively short end of the spectrum, which a typical NECO would tend to be, so the bill might be on the long extreme for a NECO, though this could be too close to be a usable feature (and not sure I can really judge this feature). The breast color may have been a little closer to DCCO than NECO, in that it seemed quite pale for a "typical" immature NECO. However, I did find an account that mentioned a very few NECOs can show a relatively pale brown breast, being more similar to the paleness shown by DCCOs--so there's apparently a little bit of variability in that feature for NECO. But on average the majority of young NECOs will show a darker brown breast color than DCCO. This bird would probably (?) be at the pale extreme, I'm guessing, for a SY NECO. I'm not sure how time of year affects this difference. I noticed that the bird was apparently acquiring some darker brown feathers in the lower center of the breast (as seen in some of the photos). At about 8pm the cormorant began to get active (it had seemed lethargic, sleeping or preening most of the time prior to this) and suddenly took flight, flying off in a W to SW direction, flying fairly low as it cleared the west side of Pond 1. Couldn't really see how far it went, if it left SJWS entirely or not. The DCCOs all looked content like they'd be spending the night on the island. But not sure if they ended up going to roost in trees somewhere in the area or not (though the light was already pretty dim).
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