The Raven Corvus corax is one of the oldest synanthropic bird species. Historical development of human settlements and cities was the reason of occupancy by ravens neighborhood of villages and town. Nowadays, suburban areas are, among forest and rural areas, habitats used by Ravens. Since end of middle ages Ravens began breeding in interior of towns in the Great Britain. During 20th century Raven occupied several big cities of Europe and North America. In Poland, the first attempts of colonization of cities took place in the 1950s in Warsaw and Kraków. During next decades Raven came back from centrum of cities and began colonized suburban zone, mainly big forests within the border of towns. Untilnow, Raven in Poland nest only in suburban zones. Observations of non-breeding pairs inside of cities are still rare. The biggest population in cities do not exceed 20 breeding pairs.

Highlights • The density of cavity trees in pine-dominated, managed forests varied in relation to stand age and was highest in stands older than 130 years of age. • Cavities excavated by woodpeckers dominated among all cavities. • The number of trees with cavities appears insufficient to ensure the effective protection of bird diversity in managed stands of Augustów Forest.

Background Nesting trees and habitat represent the key factor underpinning stand selection by forest-dwelling birds. While two large European species – the black stork (Ciconia nigra L.) and white-tailed eagle (Haliaaetus albicilla L.) – are known to require old, large trees for nesting, we sought to investigate further by comparing species requirements at the levels of the nesting tree, nesting stand, and landscape. This entailed a detailed examination of forest features within circles of radius 15 m surrounding 16 and 19 trees holding the nests of storks and eagles respectively. The same parameters were also checked in the vicinity of 50 randomly-selected mature trees. Results Our results indicate different nesting preferences, with the eagles entirely confining themselves to Scots pine (Pinus sylvestris L.) – a species also chosen by black storks, which nevertheless regularly favour pedunculate oak (Quercus robur L.). Both species select trees of greater girth than the random ones, but white-tailed eagles choose to nest in the vicinity of patches of mature old stands with a loose canopy, to the extent that nesting trees and surrounding trees are of similar ages. In contrast, black storks prefer “veteran” trees with low-set crowns that are much older than any others in their vicinity. Nesting trees of the eagles are away from roads and close to lakes, while black storks do not avoid roads. Conclusions As the ages of nesting trees of both species are greater than ages at final cutting in this region’s managed forest, silvicultural measures will need to be adjusted, with small patches of forest spared, or larger areas as “islands” of old-growth. Likewise, as tending and thinning are engaged in, certain trees with horizontal branches will need to remain, with relict trees also left untouched. As it happens, all of these recommendations are anyway key elements of close-to nature silviculture and multifunctional forestry.

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