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30 Bokotey A., Strus Iu., Dzubenko N.

In Ukrainian Polissya, storks usually build nests in the height ranges of 4-25 m (table 5).
The average nest height depends on the tree species (ANOVA: F=2,66, p=0,03) but is
usually fairly constant (10-15 m).
On the trees, nests were located mostly on side branches near the main trunk (55,7%,
n=147). 20,1% of nests (n=53) were built on side branches on some distance from the
trunk. Another 20,1% of nests (n=54) were built in the main trunk forks. Six nests (2,3%)
were located on the traditional hives in forest ("bort"), while four nests (1,5%) – in the
curvatures of the main trunk.

Table 5

Height of nest location on different trees species
in the Ukrainian Forest zone (Polissia)

Tree species M σ Min Max n
Silver birch 13,2 3,51 6 20 10
Willow 9,0 1,41 7 10 3
Alder 13,3 3,54 7 21 17
Oak 11,3 3,76 4 25 148
Powerline pole 25,0 - - - 1
Common aspen 14,1 3,04 10,5 20 10
Pine 12,1 3,73 4,5 22 88

Combined 11,9 3,85 4 25 277

Conclusions

In the Ukrainian Forest zone (Polissya) within the Rivne region, Black Stork uses for
breeding mostly mature forests with old trees located in humid places. In general, the
distribution of nests in the forests of different types reflects the structure of forests in the
region, although we found some statistically insignificant positive selectivity (shift in
occurrence/distribution) in the case of humid oak-pine forests and negative selectivity in the
case of semi-humid oak-pine and humid pure pine forests. The most preferable dominant
tree species in forest stands is Black Alder Alnus glutinosa and the least preferable – Silver
Birch Betula pendula, yet selectivity in case of prevailing tree species is also statistically
insignificant. In Polissia (Volyn, Rivne, Zhytomyr, Kyiv, Chernihiv, and Sumy regions),
the majority of nests are located on oaks Quercus robur (53,3%) and pines Pinus silvestris
(29,9%). As to the forest age, Black Storks prefers premature and mature forests
(significant) of the highest productivity classes. Our analysis has found very similar results
in comparison with other published studies.

Acknowledgments

The study was financially supported by the "CICONIA" fund within the scope of the
project "Protection and management of Black Stork populations and their habitats in the
transboundary area of Ukraine and Belarus. "
We are grateful to all those who participated in data collection, especially to Mykhailo
Franchuk, Rostyslav Zhuravchak, and Vasyl Mateichyk. Special thanks to Rivne Forestry
Agency that provided GIS layers describing forests structure.