Although size is often quoted as a field mark, it can be a difficult one to use. I used to believe I could judge any bird's size quickly in the field, but I now think that what was happening was that shape and behavior told me what species the bird was, and my mind automatically filled in the known size. In traveling outside North America I find that my first impression of the size of an unfamiliar bird may be grossly incorrect. If you are looking at an unknown bird, do not make assumptions about its size unless you see it in direct comparison to something else.
Sunday, January 15, 2006
Kaufman on size judgments in the field
Kenn Kaufman writes this on page 7 of his book "Advanced Birding" (the bold font is mine):
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4 comments:
Your quotes from Sibley and Kaufman are standard considerations of field ID that all who have considered these sightings are familiar with already, I am quite sure. The possibility of erroneous judgements of size and mental filling-in of field marks not actually seen are taken in to account when evaluating any sight record; this is in part why review committees tend to be highly dubious of a report that suggests too much detail inferrred from too little sighting. Such is not the case here; the observers readily describe both what thay saw and what they did not see.
In the Supporting Online Materials for Cornell's paper, I see one sentence of details for Sparling's sighting and two sentences of details for the Gallagher/Harrison sighting. The details of five other "robust sightings" are described within one single paragraph.
As far as I know, these details have never even been submitted to any records committee.
The State records committee has accepted the record based on Luneau's video. The sightings could be submitted also, but the State committee has already relisted the bird as extant rather than extinct. So it becomes a lower priority item and certainly not a time-critical item.
In the Supporting Online Materials for Cornell's paper, I see one sentence of details for Sparling's sighting and two sentences of details for the Gallagher/Harrison sighting. The details of five other "robust sightings" are described within one single paragraph.
I may be incorrect, but I think a recent edition of North American Birds has more details of the "robust" sightings.
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