They utter one type of call to warn of a threat from the air ​ — such as a patrolling bird of prey — ​ but emit a different call to warn of a threat approaching from the ground.
اما هر دو چه نر چه ماده اصوات کوتاهی تولید می‌کنند که مفاهیم مختلفی دارند .‏