Following the recent exchanges about recent observations of these birds I
thought it worthwhile doing a couple of graphs of GBS data covering the last
two years. I have attached the result, as a zip file to save your
bandwidth. Note that the x axis is "weeks since July 03" and NOT 'survey
week' (ie it is 6 months out of number order).
While both charts show a low levels over summer, I have probably put the
graphs the wrong way round since it is the results in the second graph, for
number of birds observed, in year 22 (2002-03) which show the major increase
in the number of birds observed after the January 2003 fires. The other
graph of flock size suggests that flock size, as Geoffrey Dabb commented, is
low in Summer. There is a suggestion, which I haven't really thought about,
that flocks build up to a secondary peak in Spring: perhaps they like to
travel to the breeding grounds in large groups???
Martin
ytbc.zip
Description: Zip compressed data
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