A throbbing or fluttering movement in the forehead of an elephant at the position where the nasal passages enter the skull (located in the center of the forehead just above the eyes), which occurs when air is pulsating through the nasal passages. This is particularly visible when a large adult male gives a deep throbbing Musth-Rumble. In some cases dust on the forehead can be dislodged by the movement and become airborne. Occasionally throbbing of the forehead can be detected when an adult female Rumbles. This fluttering is more apparent in Asian elephants who have a prominant bulge at the location where the nasal passages enter the skull. 

References: Payne et al 1986, Poole & Granli 2021. (Full reference list)

This behavior occurs in the following context(s): Advertisement & Attraction, Affiliative, Courtship