7. Uurgemiddelden grafieken
Club van Zeetrekwaarnemers Verslagen , Volume 26 - Issue 1 p. 20- 28
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 northwards (eastwards) are plotted above the abscis, while the mean numbers of birds flying southwards (westwards) are plotted below it. For most species the mean numbers of all three regions are given (Zuid Holland+IJmuiden, Noord Holland north and Wadden SEA area). Below all figures the percentages of presence are given for every month. These were calculated by dividing all hours in which a certain species was observed during the month concerned by the total number of hours observed in that month. Thus this value gives an indication about the changes of seeing that particular species in that particular month.
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