The bird repellent system is particularly adapted to repel various species of birds on and around airports, but may be readily adapted for use in other environments where birds have become a nuisance or hazard. The system includes both a ground vehicle and an airborne vehicle to optimize the effect against both sitting birds and birds in flight. Both vehicles are unmanned and operate autonomously, or by remote control as drones. The airborne vehicle is preferably a quad rotor craft for very slow and hovering flight. Both vehicles are equipped with GPS guidance and are preprogrammed to travel about a predetermined area or route. The two vehicles communicate with one another for optimum effect. Both vehicles include audio systems to broadcast startling sounds and/or bird distress cries in sound frequencies audible to humans as well as in ultrasonic frequencies known to be audible to various species of birds.
