On The Problem Of Nesting Trees Preferred By Milvus Migrans In The Forest Belts Of The South Of Western Siberia

Roman Fedorovich Bakhtin

The Shukshin Altai State Academy of Education, 53, Korolenko Street, Biysk, Altai Territory, 659333, Russian Federation

DOI : http://dx.doi.org/10.13005/bbra/1920

ABSTRACT: The paper presents the data about Black Kite nesting in forest belts in the South of Western Siberia in the Altai territory. The length of the studied plantations was 50 km. In the study, 72 nesting trees of this predator were identified. Black Kites' preferences in selecting the specie of testing trees, its ontogenetic state, trunk thickness and tree strength were tested with the use of Ivlev-Jacobs selectivity index. The results have showed that the most preferred for nesting tree species in forest belts are poplar Populus sp. (selectivity index 0.5), birch Betula sp. occupied in proportion to their abundance (-0.02), while pine Pinus silvestris and maple Acer sp. are ignored to various degrees. By the ontogenetic state, middle-aged generative trees (0.74) are preferred, and old generative trees (-0.18) are ignored to a certain degree. In respect to the diameter of nesting trees' trunks, trees 31-40 cm in diameter are preferred (0.23). In proportion to their abundance, trees 21-30 cm in diameter are used (-0.04). Trees with other trunk thickness are ignored to various degrees, up to being totally avoided. The most preferred for nesting in forest belts are the trees with the index of power of 1.6–2 (0.31). Trees with the index of 1.1 to 1.5, and 2.1 to 2.5 are used approximately in proportion to their abundance (-0.02 and -0,07, respectively), and trees with the values of this index more than 2.6 and less than 1 are almost or completely ignored.

KEYWORDS: Black Kite; nesting tree; the Ivlev-Jacobs selectivity index; forest belt; ontogenetic state; trunk diameter; index of power

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