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Paul
is certainly right with his first point (to reduce repetition, I will edit out
the rest). It is far from a new issue nor one unique to us. Raw number of
records is also very much an issue about the number of visits to the site
by people who report results. If I am reading an ABR I am satisfied with a
comment alerting the reader to the likelihood that a particular bird or group
has been recorded many times, if that is what appears likely. That is perfectly
understandable to me. Then again we should not overestimate it. Many studies,
when banding birds, have also shown that what people have assumed to be the same
birds present at a location over a long period, have in fact been many more
individuals than the casual observers had believed it to be.
I
point out that the structure of the GBS and the different use of statistics A,
W, R, G & F specifically address the main issue about repeat counts.
Such that one bird present at 1 site on 2 weeks has double the value of A, W, G,
R, but not F of one bird present at 1 site on 1 week. But not if it is recorded
at another site in the same week (W would differ). Other combinations will set
other comparisons. The GBS is at an advantage because it has a regular
structure. Other surveys have the same questions but the same questions become
harder to answer.
Repeat
counts are also useful for setting first and last dates, so don't discount their
usefulness.
Philip
The
issue of how often to record recurring sightings of the same individual bird of
a species, and how these records could be interpreted is an interesting
question, and one that regularly exercises the minds and judgement of the ABR
report writers and editors.
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