Survival, ranging, habitat choice and diet of the Northern Goshawk Accipiter gentilis during winter in Northern Finland

The winter ecology of the Northern Goshawk Accipiter gentilis was studied i n northern Finland in 1991-95. The data consist of 26 radiomarked hawks, of which 331 day and 299 night positions were located. Average range size was 9894 ha for males (minimum convex polygon, n = 43 and 6282 ha for females Cn = 11). Ranges calculated by the 75% harmonic mean contour gave range are as of 3283 ha for males (n= 3> and 2753 ha for females (n = 11). Harmonic m ean centres concentrated near human settlements, implying better food avail ability there compared with woodland areas. Some Goshawks preyed upon anima ls living in the city dump in late winter. Goshawks preferred deciduous and mature conifer forests and avoided open areas such as fields and bogs. The y also avoided very heterogeneous sites. The winter diet consisted mostly o f Mountain Hares Lt-pus timidus (30.9%), Red Squirrels Sciurus vulgaris (23 .6%), Brown Rats Rattus norvegicus (12.7%) and forest grouse Tetraonidae (2 7.1%), of which Black Grouse Tetrao tetrix was the most important (14.5%). By weight, hares constituted 70% of the biomass consumed.