Ultrasonic pest control!

Looking for a bird repellent ultrasonic device. Have loads of birds nesting in an old finca on our land and they are setting of our perimeter alarm and pooing like troopers! Yes I have an air pistol.....JOKING!!! (they are too small to hit anyway, need a machine gun!) These things send out a ultra high frequency humans cannot hear, and sends the birds away. There are loads of these things in the States but with 110 Volts and shipping its not an option. IS there anywhere here someone can recommend to buy these things? They are not normally the same as dog or cat devices?

La Marina