| 摘要 |
<p>Birds, especially, pigeons dislike the presence of a magnetic field because each bird has a biological instinctive ability of sensing the presence of the magnetic field. In order to utilize this biological instinctive sensing ability for the purpose of preventing birds from crowding at the upper part of a building, a plurality of magnetic members are disposed on an arm(s) turnably held at the uppermost end of a support column. When a bird perches on the arm, the latter is turned by the action of his own dead weight, resulting in the bird amazingly flying away from the arm. It is effective that a rotary wind blade having two magnetic members immovably secured to the opposite sides thereof is disposed at the uppermost end of each support column so as to largely affect the magnetic field induced by the magnetic members disposed on the arm and the magnetic members disposed on the rotary wind blade. Magnetic members may be disposed on a wire-shaped member tightly spanned between adjacent support columns, a bird threatening unit, a plurality of wires suspending from the upper end of an opening portion located above the veranda of a building or a similar member. <IMAGE></p> |
