© Artescienza

pilot whale

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Cetartiodactyla

Infraorder: Cetacea

Parvorder: Odontoceti

Family: Delphinidae

Genus: Globicephala

Species: Globicephala melas (Trail 1809)

Description

The pilot whale has sexual dimorphism. The male reaches 7 meters in length and about 2.3 tons in weight, the female is slightly smaller (about 5.5 meters).

The body is solid, and the rostrum is barely noticeable due to the globe shape of the head. The coloration is ebony black or dark brown in the adult, while the juveniles are light brown. In the adult, there is a white spot on the chest and belly in the shape of an upside-down anchor.

The species is distributed in temperate and subpolar waters, it is found in pelagic and coastal areas of the North Atlantic and the North Sea.
In the Mediterranean sea, it is present in the Strait of Gibraltar, Alboran Sea, and in the Provençal Ligurian Basin. In Italy, the sightings are concentrated in the Ligurian Sea and Sardinia. The only known nucleus in our area of study today seems to have disappeared.

The pilot whale is a gregarious species that form groups of a few tens up to hundreds of specimens.
The species feeds in-depth and mainly on cephalopods.

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Except for the Alboran Sea, there are insufficient data to estimate the distribution and abundance of the Mediterranean population of pilot whales, so it is impossible to determine their conservation status.
Pilot whales are incidentally killed in gillnets, bottom trawls, and longlines. In the Mediterranean, the species is still threatened by the illegal use of drift nets to catch swordfish. Other potential threats include collisions, chemical, and noise pollution.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The local Nucleus

Since 1995 a stable group of pilot whales has been documented off Ventotene Island.

In 1995 the pod was composed of 6 photo-identified individuals: three adult males (Cagliostro, Santiago, and Enea), one adult female (Señora), one juvenile female (Emma), and one immature male (Pan). The herd was led by the largest male, the “pilot” Cagliostro, as observed in other social groups of this species.

In 1996, one of the adult males (Enea) disappeared; later, in 1999, a newborn to the group was recorded. Our observations documented that Cagliostro, the “pilot”, constantly took care of the young Pan (about 5-6 years old), remaining isolated from the rest of the pod. On the other hand, the two females and the second male of the group stayed apart with the newborn, perhaps in defense of the young.

From 2000 to 2004 we regularly sighted only Cagliostro and Pan, the other members of the group were never seen again. In 2006 Cagliostro and Pan were spotted for the last time, the animals were together with a female and a newborn.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sightings have been almost always south-west of Ventotene in a very narrow stretch of sea (3 square kilometers) corresponding to a submarine crater not described in the literature, which we nicknamed “Globibar”. The last sightings of 2006, have happened instead to the south-west of Ischia, in the canyon of Punta Imperatore.

 

 

 

 

 

 

Acoustic

The pilot whale has a varied acoustic repertoire, and several associations between sounds and behavior have been documented; however, there is little information on the degree of stereotyping of whistles and the “signature” function.
Thanks to the continuity of our observations and the small size of the observed group, it was possible to record and catalog the sounds emitted by Ventotene’s pilot whales.
All whistles (n. 899) were cataloged according to their shape and assigned to individual animals by observing the air bubbles that were emitted during the production of whistles while swimming on the bow. Results of the analysis showed that pilot whales predominantly (80%) produced their own signature whistle. The songs of males were predominant (80%). All whistles had an introductory structure. The juvenile male, Pan, did not develop this introduction until 1996, and in the same year introduced an additional final vocalization (closure) to his call.