Posted by Phil Pickering (208.46.229.106) on February 20, 2002 at 21:04:41:
Looks like a puffinus shearwater based on plumage pattern, and body/head/bill shape and proportions (combination of shape/pattern wrong for fulmar, pterodromas, gulls, alcids, etc.) Pale underparts rule out Sooty, Short-tailed, and Flesh-footed. Combination of slight build, facial pattern, and uniformly dusky bill rule out Pink-footed. Overall brownish coloration and lack of defined dark pattern on the head, nape, and sides of the breast rule out Buller's. Slight build and head pattern wrong for Streaked. Facial pattern and apparently very short, blunt tail don't seem to fit (light-morph) Wedge-tailed. Seems to be a Manx/Black-vented type (of the reasonably possible species). This is supported by the mostly uniformly dark, unpatterned upperparts, slight build, proportionately large eye, and facial pattern including the dusky auriculars.
The obvious white ventral area staring us in the face seems to suggest Manx, but I think this is probably a Black-vented. The rear of the bird is such a jumble of out-of-focus feathers that it's hard to tell where the undertail, undertail coverts, and vent begin/end. I'm not sure that an extreme pale-end Black-vented couldn't have this pale a stern, anyway. And additionally, the white speckling in the upperparts (upper tertials? lower scaps?) seems kind of strange for either species to me, perhaps suggesting leucism or other genetic irregularity. A leucistic Black-vented certainly could be paler than expected in the ventral area.
The overall look to the pattern of the bird seems much better for Black-vented to me. The contrastingly paler upper nape and neck seems typical of Black-vented, and is not something I've noticed in person or in photos on Manx. My impression is that Manx are more typically uniformly dark from the body through the nape and neck, and up onto the head. The face is also quite pale, and the facial pattern and light/dark border on the sides of the breast are also somewhat undefined for Manx. I think Manx typically are more solidly dark through the face, with the light/dark border more often lower (more bill-level or below) than on this bird. The bird does seem to have a post-auricular pale area forming a sort of Manx "notch", but it also doesn't seem defined enough for a typical Manx to me. I'm not sure that a diffuse, pale post-auricular area wouldn't be typical of a pale-end Black-vented, anyway. Also, I don't recall noticing such a pronounced upper eye line/crescent on a Manx (even though it is illustrated in Sibley), while I have noticed it in a couple photos of pale-end Black-vented.
I think the very gray-brownish overall coloration (rather than darker, more neutral or slate gray) is also much better for Black-vented. The color in the scan seems to be balanced pretty well, so I think color can be used as a mark in this case. Several sources state that Manx can show a brownish hue when very worn, but I have not noticed it on the Manx I've seen in person, including multiple birds in Aug/Sept. The birds I've seen have been VERY dark, virtually blackish, without a hint of brownish tones on the upperparts, even in strong lighting.
So, pending the usual obsessive further research, gotta guess it's an (odd?) Black-vented based on gray-brown color, facial pattern, and contrastingly pale nape/neck.
Cheers,
Phil