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 en WD) as follows upper, medium and lower. 7-Day periods, in which 5 or less observation-hours were available, are marked with *. Below each 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 observation-hours 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 coastal region.