Sounds and Vocal Behavior

Can be heard both on the beach during the day and in the Atacama Desert during the night. A flock in flight produces vocalizations that suggest a whining cry.

Development

During hatching, while the chick is still breaking out of its shell, it emits the first vocalization of its life: a very vigorous and long, high-pitched note with irregular pauses.

Vocal Array

Contact Vocalization. One of its most common vocalizations is one with a nasal timbre. It starts with a low ascending glissando that stays high and then declines. Its duration is approximately 0.3 to 1.1 s. The frequency is high and varies between 1,500 K and 1,800 K in superior harmonics. This vocalization is emitted both in flight and on land: Mheaaaoooow! The pause interval between the onset of each vocalization is very variable, but, in general, it varies from 1.7 s to approximately 9 s.

Call with Vibrato. Similar to the contact vocalization, this call starts with an ascending glissando that stays on a lingering note with a clear and wide vibrato, resembling a growl. Its intensity sometimes builds up at the end: Rrrrrraaaaooowww (2(b)). It also emits a vocalization with a long vibrato at the beginning and a glissando drop. This call is very high-pitched: the pitch can be visualized in a spectrogram. The intensity and strength of this vocalization varies based on the energy of the emission. The sonogram provides an example of this call. However, in flight, at night, it is much slower and calm.

Long Call. This rhythmic chant can end with a characteristic whining vocalization: gua-gua-gua-gua-gua mheaaaaaaooow. This vocalization ends with a long note with a wide vibrato: gua-gua-gua-gua-gua - rrraaaaoooww (9–11 seconds).

Mew Call. A drawn-out moan with fluctuating pitch, sometimes almost bisyllabic: ooooooooooaaaah. Similar to Contact Vocalizations or the long note of the Long Call, but more drawn out and muffled (35 Moynihan, M. M. (1962). Hostile and sexual behaviour patterns of South American and Pacific Laridae. Behaviour. Supplement 8:1-365 Close ), like a "weird moan" (3 Howell, T. R., B. Araya, and W. R. Millie (1974). Breeding biology of the Gray Gull, Larus modestus. University of California Publications in Zoology 104:1-57. Close ).

Short Call 1. This short call resembles a meow, with a much softer intensity, lower frequency, and short duration: Meeaw! (second 0:14).

Short Call 2. This short call has a pronounced irregular and fast rhythm pattern with short onsets and tiny pauses between notes. These onsets oscillate between 4 or 10 consecutive onsets. The intensity can grow or slow down. This vocalization is very similar to the bark of a dog: Gua-guagua-gua-gua. Closely resembles the introductory notes of the Long Call. The timbre and onset of this call resemble the vocalization of the Black-necked Stilt (Himantopus mexicanus).

Alarm Call. Another short call, described as either Ka or Ha. It can be given as a single note, or more often in a series of up to 4–5 notes in quick succession (35 Moynihan, M. M. (1962). Hostile and sexual behaviour patterns of South American and Pacific Laridae. Behaviour. Supplement 8:1-365 Close ).

Flock Vocalization. Very restless, uneasy, and tumultuous sonority. Different simultaneous vocalizations can be produced by the flock, with members not always using the same pattern.

Daily Pattern of Vocalization

Calls both during the day and at night. As a result of their nocturnal vocalizations, the first colony was discovered in the desert in the Antofagasta Region because of tales and testimony from miners and saltpeter workers: “Solían oír en los meses de verano, a altas horas de la noche o al amanecer, el chillido lastimero de las garumas” ["They used to hear in the summer months, late at night or at dawn, the plaintive shriek of the garumas"] (31 Philippi, R. A., A. W. Johnson, and J. D. Goodall (1944). Expedición ornitológica al norte de Chile. Boletín del Museo Nacional de Chile, Santiago 22:65-120. Close ).

Repertoire and Delivery of Song

When giving the "Long Call" on land, it makes an ascending movement, raising its neck and singing upward, generally in a duet. It is a courtship behavior very characteristic of the species. However, it does not always end with the same intensity, and can vary.

No non-vocal sounds known.