ML32090101
Contributor
Date
Location
- Age and sex
- Adult, Unknown sex - 1; Immature Unknown sex - 1
Media notes
Determination of the species identification as Thick-billed Murre adult is on the bases of (a) general heavy black-on-white coloration; (b) stocky build and head; (c) a relatively short bill with a whitish tomial streak and a distinctly curved culmen near the tip (indicating Thick-billed Murre), which are unique to this species; (d) blackish color exhibiting less brown coloration than with Common Murre; (e) absence of any noticeable side streaks (unlike the Common Murre); and (f) tail length and shape (i.e., tail relatively short and rounded and ending close to the tips of the folded primaries) works strongly against Razorbill, which has a longer tail that ends noticeably beyond the folded primaries and has more pointed central rectrices, giving a pointed appearance; and (h) the bill on this adult Thick-billed Murre decidedly rules out Razorbill, for it is neither blunt enough nor swollen-tipped enough for Razorbill, and it lacks the noticeable vertical bill-groove and the white bill markings usually evident in adult Razorbills in all plumages (see illustrations in Mullarney et al., 1999, p. 197; reference given elsewhere herein). (See, also, important comments on age as discussed in association with photo ML32090151, which shows a first-winter Thick-billed Murre.)
Observation details
Two individuals of this species are documented here, via photographs, an adult (long slender bill) and an immature individual (short, less slender bill). Three different photos are provided herewith, but each is provided in two different versions (but both versions involve some cropping from the full frame). One version of each shows it without any electronic correction to remove the bothersome and potentially misleading reddish color in the originals that was due to chromatic aberration (i.e., differential diffraction of wavelengths). The chromatic aberration presumably was due, in large part, if not entirely, to the fact that in all of the photos--but in some much more than in others--the optical axis of the camera lens had inadvertently been tilted a bit relative to that of the spotting scope. This was possible because the camera's lens was simply hand-held up to the eyepiece of the scope, and it was easy to displace it a bit, especially when triggering the shot by pressing a button on the camera. Nonetheless, this technique made possible photos adequate both for species identification and determination of age of both of the Thick-billed Murres. One was an adult and the other, a first-winter bird.
Technical information
- Model
- Canon EOS 10D
- ISO
- 400
- Focal length
- 50 mm
- Flash
- Flash did not fire
- f-stop
- f/1.8
- Shutter speed
- 1/45 sec
- Dimensions
- 2150 pixels x 1434 pixels
- Original file size
- 324.83 KB