Choosing the trees for nesting by the Buzzard, Goshawk and Raven in the Augustow Forest

Preferences of the Buzzard, Goshawk and Raven in choosing the trees for nesting were studied in northern part of the Augustow Forest (NE Poland) in 2014-2016 years. Study area is dominated by fresh and mixed fresh sites with Scots pine as a dominant species (86% of the forest area). Nests were searched in stands older than 60 years. We found 60 nests of Buzzard, 11 of Goshawk, and 31 of Raven. The diameter and the height of nest trees, the height of nest location, and length of tree crowns were measured. Diameter and height of surrounding trees were also determined. In total, 11 features of nest trees were assessed. For the location their nests, all analysed bird species preferred trees bigger and higher than neighbouring ones. The oldest stands (above 100 years old) were also preferred. The Raven built nests on trees average 139 years old, Goshawk - 119, while Buzzard - 109. Raven nested only on Scots pine, Goshawk on Norway spruce and Scots pine, while Buzzard on silver birch, Scots pine, European larch and Norway spruce. The Buzzard selected for nest trees growing in average distance about 1500 m from forest edge, while Goshawk and Raven preferred nest in a similar distance from the forest edge (707-783 m). Distance of the nests from forest road were similar for Buzzard and Goshawk - about 60 m, and in case Raven it was only 38 m. Raven chose for nesting old-growth islands located on forest edge, or even single old tree growing on plantation. The greatest plasticity in the nest location and habitat diversity was found for Buzzard. Both Goshawk and Raven had more precisely marked habitat and nest preferences.