In the following figures the mean numbers of birds per hour per seven-day period are given for each coastal region. In these the mean numbers of birds flying north (east)wards are plotted above the abscis, while the mean numbers of birds flying south(west)wards are plotted below it. For most species the mean numbers of all three regions are given (Zuid-Holland + IJmuiden, Noord-Holland and Wadden Isles). Below each figure the percentages of presence are given for each month. These were obtained by dividing all hours in which a species was observed during a month by the total number of observed hours in that particular month. Thus this value gives an indication of the chances of seeing that particular species in that particular month.