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Summary: Occurrence of raptors, owls and mammals at feeding sites of winter birds in Finland

Risto A. Väisänen 1999: Talvilintujen ruokintapaikoilla vierailevat petolinnut ja nisäkkäät. Linnut 4/1999 (vol 34), pp. 8-11.

Birds were counted at 455 winter feeding sites from 1 October to 30 April during 14 two-week periods in the winters 1988/89-1998/99 (the period 16-30 April has, however, been censused during the last two winters only) (Fig. 1). For each species, at least the maximum number of individuals observed on the "best day" was reported from each period. The average numbers of the most common raptors and owls observed at the feeding sites are shown in Fig. 2. In S Finland Sparrowhawk visits are most abundant in mid-winter, but in Central Finland also during the autumn and spring migration periods. In Lapland sparrowhawks are rare in wintertime. Visits of the Pygmy Owl are most common in mid-winter. Later the owls remain more on their breeding territories, but appear again at feeding sites in late April, when males hunt food for incubating females and hatching young. Visits of the two other species of Fig. 2 are rare. The Goshawk becomes slightly more common from October-December to January-February. The Tengmalm's Owl has been observed most often in October, when this species often is irruptive, and in late winter. (High values of the y-axis have been caused by numerous observations at sites where observers have learnt to detect this nocturnal species.)

The presence of mammals at winter feeding is shown in Fig. 3. The red squirrel has been the most common mammal, being recorded at 71 % of the sites and as a regular visitor at 50 % (often there were 2-3 squirrels, see Fig. 4). Three other species or species groups have been present at about half of the sites (Fig. 3): hares, mice plus voles, and cats. Cats (often 2-3 individuals) have been regular visitors in one third of the feeding sites in inhabited areas, but stoats and weasels have been rather rare. Because the rough data so far collected on mammals are promising, project instructions have been amended to include records of well known mammal species along the same principles applied for birds.