Communication and Perception
Black noddies use a variety of vocalizations and visual displays to communicate with conspecifics. Young use a begging call to beg for food. Main call types are identified as "chatters," "rattles," and "croaks." Black noddies do not sing and vocalizations don't vary seasonally. Foraging flocks constantly call and calls are common when nesting and roosting. Chatters are typically used in flight and may be a contact call. Rattles are alarm calls. Croaks may be given when an intruder is detected. Black noddies also use bill clacking during visual displays.
Black noddies employ a variety of visual displays to attract mates and in agonistic interactions. Displays include "nodding," "gaping," "foot-looking," "head-shaking," "bridling," "chin-up," and "appeasement." Many of these visual displays are used both in agonistic interactions, as when directed aggressively at an intruder, and in mating interactions. For example, nodding occurs when an intruder is approaching and also when a mate approaches. In the former context it is used to drive the intruder away, in the latter context it is used to greet a mate. Bridling - which involves forward and backward movements of the head, accompanied by opening and closing of the bill - advertises territory ownership to both mates and intruders. Appeasement displays are usually by juveniles, who point their bills downwards to avoid an aggressive interaction. This is similar to foot-looking, which also is used to avoid aggression.
Communication Channels: visual ; acoustic