Subject: Pacific or Arctic Loon?
Date: Apr 29 10:50:27 1997
From: Don Cecile - dcecile at cln.etc.bc.ca



>Hi tweets, as the shorebird migration gears up for full swing, the waterfowl
>tapers off and loons in particular seem to have, for the most part, moved
>out of the local area. What I saw last weekend was an intriguing looking
>loon. It was a long ways off, typical of Pacific and Red-throated Loons,
>the Common Loon often much closer to shore... but it had white sides! Taken
>by itself, this field mark is rather useless but is very visible from a long
>distance and would likely be the first field mark that would steer an
>observer into speculation. Is it a Pacific or is it an Arctic Loon? For
>starters, I had to watch the bird for a few moments to be certain that the
>white was not simply due to the way the bird was sitting on the water (they
>sometimes preen with their bellies exposed-showing what appear to be white
>sides). Interestingly, the white sides were visible at all times during a 5
>minute observation. I was not pleased that the bird was a great distance
>away but nevertheless, I was determined that I would not let a potential
>Arctic Loon escape. As I watched the bird, I attempted to sort out other
>features that would coincide with either Pacific or Arctic field marks. As
>far as size goes, it appeared much smaller than the Common Loons that were
>nearby, perhaps too small for what I would expect for Arctic. It was in
>basic plumage, a few white spots were appearing on the otherwise dark
>mantle. I thought it's profile was smooth and sleek like a Pacific Loon, it
>should be more block-headed for Arctic, approaching the head-shape of Common
>Loon. The white sides appeared to darken toward the rear flanks and I
>thought this area should still be rather white for an Artic Loon. No
>chinstrap was visible but the bird was much too far away to see this.
>The bill was held horizontally as one would expect for Pacific Loon.
>
>I have seen Pacific Loons show white sides before, but never to this extent,
>so I was puzzled for a while. I was also hopeful that I might 'turn it into
>an Arctic' but too many clues led toward a Pacific Identification. In fact,
>as far as I could tell, it only had one arctic loon feature. This
>experience reminded me how easily one can put too much weight on one or two
>fieldmarks and mistake an identification whereas gathering as much evidence
>as possible is a much more reliable method.
>
>A few questions that I have are:
>
>1) What would be the most likely time to find an overdue Arctic Loon in the
>Pacific Northwest?
>
>2) would one expect to find an arctic loon in a mixed flock with Pacifics?
>or by itself?
>
>3) what are the chances of finding one close enough to shore that one might
>be better able to scrutinize its markings rather than relying on potentially
>misleading field marks like the bird in question. ( in other words, do
>Arctics prefer deeper waters?)
>
>
>
>cheers,
>
>Don Cecile
>dcecile at cln.etc.bc.ca
>
>
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>
>
cheers,

Don Cecile
dcecile at cln.etc.bc.ca