6. De uurgemiddelde-grafieken
Club van Zeetrekwaarnemers Verslagen , Volume 32 - Issue 1 p. 13- 20
In the figures, the mean numbers of birds per hour per 7-day-period are given for each coastal region. 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. For all species the mean numbers are given for all 3 regions (ZH, NH & Wd) as follows: upper, medium and lower. 7-day-periods, in which less than 6 observation-hours were available, are marked with *. Below each region-figure the percentages of presence are given for each month. These were obtained by dividing the number of hours, in which a certain species was seen during a certain month by the total number of observationhours in that particular month in that particular region. Thus this value gives an indication of the chances of seeing that particular species in that particular month in that particular region.
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