7. De uurgemiddelde-grafieken
Club van Zeetrekwaarnemers Verslagen , Volume 33 - Issue 1 p. 14- 21
In the figures the mean numbers of birds per hour per 7-day-period for the coastal regions ZH and NH are given. In these the mean numbers of birds flying N(E)-wards are plotted above the abscis, while the mean numbers of birds flying S(W)-wards are plotted below the abscis. The upper figures for each species are from ZH, the lower ones from NH. 7-day-periods, in which less than 6 observation-hours were available, are marked with *. Below each region-figure the percetages of presence are given for each month. These were obtained by dividing the number of hours, in which a certain species was seen, by the total number of observation-hours in that particular month in that particular region. Thus this value gives an indication of the chances of encountering that particular species in that particular month in that particular region.
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