PROBLEM TO BE SOLVED: To provide a bird damage prevention device which can easily pass between a set of edge lines. SOLUTION: A bird damage prevention tool 10 is arranged in two stages in a tubular member 11 extending straight in the axial direction of the tubular member 11, and a plurality of branch members 12 and 13 radially protruding from the outer circumference of the tubular member 11, and a tubular member 11. The main shaft member 15 and the base end portion that are freely inserted inside the member 11 are fixed to the outer periphery of the main shaft member 15, and the tip end side advances and retreats in a state of being inclined downward from the tip edge of the branch members 12, 13, and 14 in the outer peripheral direction. A plurality of branch rods 16 that can be freely projected, and needle leaf members 17 and 17 that are bifurcated from the middle portion to the tip portion of the branch rods are provided. In a state where the spindle member 15 with a plurality of branch rods 16 moves toward the base end portion side of the tubular member 11, the diameter of the virtual circumference connecting the tip edges of the plurality of branch rods 16 is expanded, and the plurality of branch rods 16 are expanded. In a state where the attached spindle member 15 is moved toward the tip end side of the tubular member 11, the diameter of the virtual circumference connecting the tip edges of the plurality of branch rods 16 can be reduced. [Selection diagram] Fig. 1【課題】一組の縁線の間を容易に通過できる鳥害防止具を提供する。【解決手段】鳥害防止具１０は、真直に延びる管状部材１１、管状部材１１の軸方向に二段に配置し、管状部材１１の外周から放射状に突出した複数の分岐部材１２・１３、管状部材１１の内部に挿通自在に配置した主軸部材１５、基端部を主軸部材１５の外周に固定し、先端部側が分岐部材１２・１３・１４の先端縁から外周方向に下り傾斜した状態で進退自在に突出できる複数の枝棒１６、及び、枝棒の中間部から先端部に向けて二股に分岐した針葉部材１７・１７を備える。複数の枝棒１６付き主軸部材１５が管状部材１１の基端部側に向かって移動した状態では、複数の枝棒１６の先端縁を結ぶ仮想の円周を拡径し、複数の枝棒１６付き主軸部材１５が管状部材１１の先端部側に向かって移動した状態では、複数の枝棒１６の先端縁を結ぶ仮想の円周を縮径できる。【選択図】図１
