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. 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. 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.

中文翻译：

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白尾鹰和黑鹳的巢穴选择-对保护实践的意义

筑巢树木和栖息地代表了森林鸟类选择林分的关键因素。虽然已知两种欧洲大型树种–黑鹳（Ciconia nigra L.）和白尾鹰（Haliaaetus albicilla L.）–需要老大树来筑巢，但我们试图通过在水平上比较物种需求来进一步调查的嵌套树，嵌套架和景观。这需要对半径为15 m的圆内的森林特征进行详细检查，围绕16棵和19棵分别拥有鹳和老鹰巢的树木。在50棵随机选择的成熟树木附近也检查了相同的参数。我们的结果表明了不同的筑巢偏好，老鹰将自己完全限制在苏格兰松（Pinus sylvestris L。）（黑鹳也选择了该物种，然而，它经常喜欢带花梗的橡木（Quercus robur L.）。两种树都选择了比随机树大的周长的树，但是白尾鹰选择在具有松散的树冠的成熟老林的斑块附近筑巢，其程度为筑巢树和周围树的年龄相似。相比之下，黑鹳更喜欢树冠矮小的“老手”树，这些树冠比附近的树老得多。老鹰的筑巢树远离道路，靠近湖泊，而黑鹳却避开道路。由于该地区的受管理森林中两种树种的筑巢年龄均大于最终伐木的年龄，因此需要调整造林措施，保留少量的森林，或将较大的区域作为老树的“孤岛”。同样，随着抚育和细化的进行，某些带有水平树枝的树木将需要保留，而残存的树木也将保持原状。碰巧的是，所有这些建议都是接近自然造林和多功能林业的关键要素。