Ospreys use several different vocalizations to communicate with one another. Up to five different calls have been recognized by researchers. These calls are nearly always associated with a visual display, such as a characteristic flight or posture. Vocalizations are used for begging, alarm, courtship, and nest defense. One notable display is the “sky-dance,” which is an elaborate aerial display performed by males during courtship and early incubation. During this display, a male carrying a fish or nest material gives a screaming call while simultaneously performing short undulating flights separated by periods of hovering. Alarm calls are often given when a potential predator or disturbance such as a boat or human approaches the nest. These calls are usually accompanied by erect posturing and diving flight.