Abstract
In Finland, population monitoring for both diurnal and nocturnal raptors has been almost entirely based on fieldwork carried out by voluntary raptor ringers. Responsible organisations include the Finnish Museum of Natural History, with economic support for administration from the Ministry of Environment, “Metsahallitus” (former National Board of Forestry) and WWF Finland. Since the early 1970s, numbers and productivity of four endangered species, the White-tailed Eagle Haliaeetus albicilla, Golden Eagle Aquila chrysaetos, Osprey Pandion haliaetus and Peregrine Falcon Falco peregrinus have been monitored by country-wide Comprehensive Surveys, with the aim of checking all known nest sites of these species every year. The Gyrfalcon F. rusticolus was included in this group in the late 1990s. Data for monitoring the populations of the other raptor species have been gathered by the Raptor Grid and Raptor Questionnaire projects. The Raptor Grid project produces annual population indices, which are calculated from the data collected from 10 × 10 km study plots (n = ca. 130/year) and quite well reflect the annual population fluctuations and longterm trends of seven common species of diurnal and six species of nocturnal raptors breeding in the southern part of Finland. For the rest of the species, which are either rare all over Finland or breed mostly in the north, outside the good coverage of the distribution of Raptor Grid study plots, conclusions on population changes are based on the total numbers of occupied territories and active nests reported annually by the Raptor Questionnaires