Figure 4. Frequency distribution of Lesser kestrel colony sizes in 1994 in the Guadalquivir Valley (SW Spain) (data from [33], [35]).
Multiplicative bins in a log-log plot are used such as in Figure 3c. Colony sizes of one, that is, solitary nests, were not included in function fitting because we know that their frequency was underestimated. This is because of the low value of these solitary settlements for estimating population size (which was the aim of this survey) jointly with the high cost of searching for all of them because these are the most abundant and less conspicuous colony sizes. A truncated power law with a breakpoint at ca.18 pairs achieved a high fit to the data (R 2>0.9).