Università degli Studi di Pavia

Centro Interdisciplinare di Bioacustica e Ricerche Ambientali

The voices of marine mammals of the Mediterranean Sea

Species occasionally entering in the Mediterranean Sea

Orcinus orca

Killer whales have been extensively studied for their acoustic and social behaviour in particular on the pacific coast of Canada, where resident groups have been observed for many years. These animals are very vocal: they produce echolocation clicks and frequency modulated whistles rarely exceeding 5 kHz; frequently, whistles begin with short sequences of clicks with dominant energy at low frequency.
Individuals may have whistles with well recognizable shapes that can be used by researchers for individual recognition. On the Pacific coast of Canada killer whales live in stable groups, denominated pods, that regularly patrol the coast and the channels among the various islands; individuals in the pods can be recognized with the photo-identification of the dorsal fin and also with the whistles emitted by individual components. With hydrophones located in key points along the coast, the researchers can control the movements of the various pods.
It is interesting to notice that the killer whales living offshore, that can be isolated animals or small and dynamic groups, have a very different acoustic behaviour. They are normally silent to do raids close to the coast to find preys. This is one of the few examples on highly diversified acoustic behaviors in the same species. There are no recordings of killer whales occasionally entered in the Mediterranean Sea.

Killer whale sounds are mostly modulated tonals but they also emit echolocation pulses.

Pseudorca crassidens

The false killer whale has been relatively well-studied in terms of its echolocation characteristics and capabilities, largely due to studies from captive animals. As yet, no data from recordings of wild animals have been reported. Although this species produces whistles too, these vocalisations have not been studied in depth. The whistles are usually between 3 and 11 kHz and may last up to 1 sec.

Megaptera novaeangliae

The humpback whale is probably the most known species because of its “songs” composed by notes organized in sentences and in themes that are structured with characteristic, constant and repeated rhythms. It has been shown that different populations have different songs, though songs are subject to progressive changes during the years. Also, when groups with different songs come into contact, they can influence each other and new songs can be elaborated by incorporating new notes or new strophes.
The notes that compose the songs are mostly modulated tones, but there are also non tonal sounds with extremely varied features that seem puffs, rolls of drums, gurgles, meows, etc.

Balaenoptera acutorostrata

Like in most Balaenopteridae the acoustic repertoire of the Minke whale is relatively limited and simple; the most common vocalization is made by fast series of low frequency pulses with most energy below 500 Hz. The documented repertoire also includes a variety of sounds similar to grumbling and to modulated tones.
There are no recordings made in the Mediterranean Sea.

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Created June 2005, updated August 2005