6. Uurgemiddelde-grafieken

In the following figures the seasonal pattern of a number of species is presented, expressed as hourly averages per week. The data above the horizontal abscis refer to birds flying north. The data below this abscis to birds flying south. Due to an uneven coverage in Wd the figures are restricted to NH & ZH. Weeks with 5 or less observation-hours are marked with an asterisk (*). Below the figures the percentage of presence is given for each month. This percentage expresses the ratio of hours in which a species is recorded and the total number of observation-hours.