09.11.2018 – Nocturnal sprinters
Sightings involving Short-finned pilot whales (Globicephala macrorhynchus) are always breathtaking. The animals gentle nature and their unique social dynamic never fails to capture the hearts of our guests on board. What makes a sighting involving these deep-diving delphinids especially remarkable is the soft silence that prevails on board during our moments with these animals at sea. The animals lethargic, calm movements at the surface are largely responsible for this beautiful silence.
Pilot whales feed on squid making them so called teuthophages and the animals perform a number of deep-dives to forage for their prey. Despite some of these dives being incredibly deep, with the deepest dive documented around the island being 997m (!!), they are relatively short and range between 10-20 minutes. In contrast to other teuthophagous cetaceans such as beaked whales or Sperm whales (Physeter macrocephalus), foraging behaviour of Pilot whales is much more energetic at larger depths. The animals engage in a sort of sprint to catch their prey, reaching speeds of up to 6m/s during their dives and a pursuit velocity of 9m/s during their hunts. The animals high metabolism makes such sprint dives possible but to avoid unnecessary energy expenditure, these intelligent creatures wait for nightfall. It is during the darker hours where the squid vertically migrate to shallower areas of the water column, which allows the cetaceans to spare themselves a couple of hundred metres dive depth.
The daytime hours are usually used for more relaxing activities at the surface, where the whales tend to the younger members of their pod, engage in a variety of social activities or simply drift at the surface, in a behaviour referred to as logging. While these daytime activities masterfully disguise the incredible speed of these formidable nocturnal hunters, they also give us the chance to peacefully observe them and enjoy moments of tranquility out on the Atlantic ocean.
By Paula Thake
Sightings of the day
10:00 Short-finned pilot whales