Scientific publications

Since 1971, authorized voluntary ringers have checked almost all known Finnish nest sites of the Osprey Pandion haliaetus annually. Finnish Osprey population remained on the same level through the seventies, increased from 1982 to 1994 by about 3% per year and, since then, has remained "stable". In 2005, of 1541 potential nest sites checked, 926 were occupied, 753 active and 699 successful. Productivity has improved considerably during the last decades and was in 1996–2005: 1.65 large nestlings per occupied territory, 2.04 per active nest and 2.25 per successful nest. The positive trend of Finnish Osprey population can be attributed (1) to decreased persecution during migration and wintering, (2) to decreased impact of environmental toxicants, and (3) to construction of artificial nests to compensate the losses caused by modern forestry. At present, almost 50% of the Finnish Ospreys breed in artificial nests constructed by voluntary ringers.