evaluation of sound as a deterrent for reducing bird damage to farm fields

birds, sometimes numbering in millions, can cause serious damage to grain fields. in order to find a method to accordance with environmental issues and effective in controlling these birds, in this research, the effect of sound was studied for keep birds away. the broadcast unit was developed with the following design criteria: 1) three sound levels of hawk, gas gun and sparrow distress, with frequencies of 1, 5 and 10 khz. 2) the combination of the sounds of cannon gas and sparrow distress with a frequency of 5 khz and 3) in the morning and evening. the result showed percent flight birds was by mixture sound 92.46, gas gun 82.90, sparrow distress 74.58 and hawk 48.22. there was no significant difference between numbers of bird’s flight after sound producing in the different frequencies. also, it was recognized that percent of flight birds in the morning was 8.06 more than in the afternoon.