MEDITERRANEAN PILOT WHALES

 

 

 

Photographs © Delphis mdc do not copy, use or circulate without permission

Long finned pilot whale (Globicephala melas) is a rare species in the Mediterranean Sea, relatively common only in the Alboran Sea and in the Strait of Gibraltar.

In 1995 we encountered for the first time a free-ranging pod of long finned pilot whales off the south-western coast of the island of Ventotene in the Archipelago Pontino (Tyrrhenian Sea, Italy).

This area has been the object of a long term study on Cetaceans since 1991. From 1995 to 2003 we observed, every year, this single stable pod of long finned pilot whales that seems to be seasonally resident off Ventotene island.

 

 

The sightings occurred from June to October, with a peak in September, when the animals occurred for 4 sequential days. Sightings were located within a relatively small area (3 Km2), mainly between 500 and 700 m depth (average depth 663.6±96.6 m, range 150/800), corresponding to a submarine crater not described in literature. We named this area "Globibar".

During the early morning hours the long finned whales were feeding with fast swimming behaviour and long and deep divings (> 4 minutes) recognizable by the strong bending of the caudal part. The resting behaviour was characterised by slow swimming, synchronous breathing and passive drifting into the current. These behaviours were interspaced with social interactions between pod members evidenced by modular whistles.

 

Through the years, whales' number in the pod decreased from 6 to 2.

In 1995 the pod was composed by six individuals: three adult males (Cagliostro ~7m length, Santiago ~6,5 m and Enea ~6 m), one adult female (Señora ~5,5 m), one juvenile female (Emma ~3 m; estimated age: 5 years), and one immature of unknown sex (Pan ~2,5 m; estimated age: 1-2 years). In 1996 Enea disappeared and was never sighted again.

The pod was headed by the largest male, the "pilot" Cagliostro, as observed in other social groups of this species.

 

 

In June 1999 we had a newborn in the group and the pod separated into two parts.

The "pilot" was taking constantly care of the juvanile Pan (now 8-9 years-old), isolating him from the rest of the pod. On the other hand, the two females and the other male of the group were taking care of the newborn, in a way that it was impossible to approach the calf closer than 100 m distance.

From 2000 to 2003 we encountered only Cagliostro and Pan.

 

 

 

 

Literature data on population genetics of this species revealed that pods contain related individuals and that males are rarely the fathers of the calves they accompany.

It is unknown also if adult males stay with the original, native pod, or live apart and move from one pod to another. Due to the fact that field observations of this species are limited, it's still unclear in which way adult males may help and interact with their relatives.