PILOT WHALE – AWF Research Team ‘ status update April 2011
CLASS:
ORDER:
SUBORDER:
FAMILY:
GENUS:
MAMMALIA
CETACEA
ODONTOCETI
DELPHINIDAE
GLOBICEPHALA
SPECIES:
melaena (long-finned)
macrorhynchus (short-finned)
The social structure of Pilot Whales
1. Pilot Whales live in cohesive long-term social units called pods.
2. The size of a pod usually varies from fewer than 5 to about 20 individuals.
3. Pods usually consist of males, females, and calves of varying ages. Females and juveniles
generally remain in the center of the pod, while adult males swim at the wings.
4. The most fundamental social units in a resident pod are maternal groups. A maternal group
consists of a mother and her younger offspring. One or more maternal groups may travel
together in a ‘subpod’. Whales in a ‘subpod’ are likely to be closely related; a ‘subpod’ contains
mothers, daughters, sisters and cousins.
5. A clan is a social level above the pod level. Clans are made up of pods in an area with similar
dialects and are thought to be related. These pods may have developed from one ancestral pod
that grew and fragmented over time.
6. Finally, the top level of the Pilot Whale social structure is a community. A community is
composed of several pods that have been seen to travel together. Pods from one community
have not been observed traveling with those of another, even if their ranges overlap.
8. There is an occasional exchange of members between pods, especially during breeding
season.
9. They live in complex family group hierarchies, similar to lions. There is a bull male in the
pod, which can sometimes be seen.
Identification
Short-finned pilot whales are easy to study for a number of reasons. During the day (especially
the morning) they can be found logging at the surface of the water where they recuperate from
their night-time hunting efforts in shallower, warm water. For this reason, the species is very
easy to find and to photograph. Photographing is an essential part of research because each
individual animal has a unique dorsal fin on its back. A Pilot Whales dorsal fin is similar to that
of a humans finger print; each is completely different to another and no two will ever be the
same. All these can be photographed and compared to a catalogue of known individuals. This
catalogue has been created by the Atlantic Whale Foundation and consists of nearly 800 named
individuals.
Feeding
Short finned Pilot Whales are actually a type of dolphin. They grow a maximum of 7m long,
with males being bigger than females. Short-finned pilot whales are active hunters, and almost
all of their diet consists of squid. They are specialist in catching giant squid and have many
physical adaptations to allow them to do so. They have a rounded melon (forehead) which
contains an advanced echo-location system, whereby the pilot whales can use sound to create a
picture of their surroundings in low/no light conditions. The large surface area of the head
maximizes this ability, enabling pilot whales to catch squid at depths where light doesn’t reach.
Pilot whales’ second adaptation is an area of the head containing a waxy substance called
spermaceti. This spermaceti is on the threshold between being a solid and a liquid. Special blood
vessels which run through the spermaceti can control blood flow to the area by dilating or
constricting, either allowing blood flow or denying blood flow to the area. This blood flow alters
the temperature of the spermaceti and thus its state. This density change allows the pilot whale to
alter its buoyancy in the water using minimal energy.
Mating and breeding
Males reach sexual maturity at about 15 to 16 feet (4.6 m) and 12 years of age. Females reach
sexual maturity at about 12 feet (3.7 m) and 6 to 7 years of age. Gestation lasts approximately 12
to15 months and calving occurs once every 3 to 5 years. Calves are generally 6 feet (1.8 m) at
birth, and weigh about 225 pounds. The calf nurses for up to 22 months, with some evidence for
longer lactation and extensive mother calf bonds. Most calves are born in the summer, though
some calving occurs throughout the year. The males may compete for mates with fights
involving butting, biting, and ramming. Mating also involves these activities, and some females
carry scars from bites inflicted by males during the breeding season. Females have been
observed to have calves as late as 35 years old, and lactate as late as 51. This evidence indicates
that females may nurse their last calf until puberty (up to 10 years in males).
Population
Population estimates over the past 13 years using the Atlantic Whale Foundation’s data suggest
that there are some 1,000 Short-Finned Pilot Whales which frequent the water off the South West
coast of Tenerife. Out of these thousand not all are thought to be resident. It is probable that half
of these animals will be present in the same location throughout the year, whilst others are
possibly undergoing small scale migrations or are transient.
Pilot Whales are matriarchal living family groups of 15-20 animals. Through our research work
the AWF is following seven families.
Conservation status
Pilot whales are often found in captivity as they survive there and are easily trained. They have
been trained by the US Navy to locate military equipment from deep ocean depths for retrieval.
Pilot whales are also often associated with mass stranding’ of several hundred animals. The
cause of the mass stranding’ is unknown, although several theories exist such as sonar problems
or parasitic infections that interfere with the central nervous system causing neurological
disorders.
The conservation status of the short finned Pilot Whale is currently unknown as there is such
little research carried out on them. However, we know that there is still slaughter carried out
every year and so as far as we know we could be studying an endangered species.
Rebecca Creed