Sounds

“Gannets are noisy birds and the metallic clangour of a great colony in uproar imparts some of the excitement which grips the birds. I have sometimes squatted in the very heart of a dense nesting mass in the sunset of a fine July evening, when the flood of incoming birds stirred the group to a frenzy of calling as partners Fenced and single birds Bowed. Waves of harsh sound rose to a crescendo and died away whilst white plumage glowed in the serried ranks” (Nelson 1978a: 39).

Given the excitement of the colony that Nelson describes, it is a pity that more is not known of the vocalizations and their functions in this species.

Development

Cheeping calls given from pipped egg (W. A. Montevecchi pers. comm.); later replaced by high-intensity yip Food Call. Young utter excited Yapping Calls, like barking of small dog, in aggression toward trespassing chicks from other nests, during “attacks” on parents, and during Bowing display by older young. Vocalizations presumably not learned (given lack of evidence for vocal learning in gannets or close relatives—but no one seems to have studied this matter, either), and no information on how calls of young give way to adult calls (Nelson 1978a).

Vocal Array

Sounds of adults have been grouped into 3 types.

Figure 3 . Also arrrrr, arrah, or urrah rah rah, given by both male and female. Also called the “landing call,” as 6–12 of these loud, harsh calls are given at rate of about 2–4/s when landing, increasing in both loudness and rate as landing approaches, with a final “shout” just before landing. Also given when Bowing, Mutual Fencing, Menacing, and fighting. During the Bowing display, a gannet calls urrah loudly 10–30 times; loud urrah s used during Mutual Fencing, intensity of calls depending on intensity of visual display (see Behavior, below).

Quality of Urrah Call varies with circumstance. When heard at its loudest, at close quarters, it is a brassy note of deafening volume, forming background clamor at a gannetry. Excited calling that occurs when gannets are fishing or gathering nest material (both communal activities) is slightly different in quality; rather shorter rah rah and often gruffer but less metallic. Alarm version loud and staccato, repeated 3 or 4 times on a descending scale. Might be a subtle sex difference in Urrah Call detectable by human ear, as with Australasian Gan-net, but nothing striking as among some closely related boobies (Nelson 1978a).

Uttered at colony as a bird begins to take off or after a hop or a short run, soft and attenuated like a hollow groan. Thought by some to be simply a consequence of the strained body position during takeoff, as a similar sound can be evoked by pressing on a corpse and forcibly expelling air; sound also given by bird in normal body postures, however, so sound must be “voluntary.”

While at sea, gannets utter a soft krok krok, much like the call of a young Common Raven (Corvus corax), hence the old German name of Seerabe (sea raven). Given in level flight, but also while diving and swimming on surface.

Geographic Variation

No information.

Phenology

No information.

Daily Pattern

No information.

Places Of Vocalizing

See above.

Repertoire And Delivery Of Songs

Does not have a “song” in usual sense of the word.

Social Context And Presumed Functions

See above.

Amplitude envelope of the Urrah Call differs among individuals, perhaps providing cues used in individual recognition. A paired bird responds selectively to played-back Urrah Calls of its mate; data less convincing for adults recognizing neighbors and for chicks recognizing parents, though Nelson (1978a) is confident of these abilities.

While copulating, male waves his outspread wings and patters noisily with his feet, which move singly or in series—in latter case, he rests on his tarsi. During Mutual Fencing, bills hitting against one another can at times produce a soft, metallic clicking barely discernible over all the accompanying loud calling (Nelson 1978a, W. A. Montevecchi pers. comm.).