21.05.2019 – Golden brown
Our guests aboard the Stenella this morning managed to enjoy lovely sightings with a very surface-active group of Bottlenose dolphins (Tursiops truncatus). I was the guide on board the Ribeira Brava today during a rather challenging tour regarding our sightings. Our spotter searched far and wide for cetaceans before discovering a small group of Blainville’s beaked whales (Mesoplodon densirostris) around 4 nautical miles outside the coastline of Calheta.
In contrast to many of the other interactive members of the toothed whale family (Odontoceti), beaked whales tend to display a quite timid behaviour and often avoid approaching boats. Little is known about the estimated 22 species in this group of cetaceans as they spend most of their time foraging and socialising in their deep-sea habitat. In the dark ocean the whales use their biosonar to navigate and track prey which the majority of them ingest through suction feeding. Communication is also thought to occur at greater depths to avoid predation by larger whales such as Orcas (Orcinus orca). Their almost complete reliance on their bioacoustics makes them very sensitive to noise which adds to the fact that many species are difficult to distinguish at the surface, challenging scientists in estimating their actual abundances. In fact, the existence of several beaked whale species is only known through the cadavers of stranded animals.
The Blainvilles are a small exception to the rule; they happen to be one of the four relatively well-known beaked whale species due to their curious nature. Our team even had some lucky moments where we enjoyed some close encounters with these mysterious creatures. Moreover, their golden-brown skin color that is thought to be caused by a dermal parasite gives them away immediately as well as the two unmistakeable tusks on the lower jaw of the males. Unfortunately, these features could not be appreciated today due to the very evasive nature of the small group but, nonetheless, sightings like these can always be appreciated. Madeira is thought to be one of the best places in the world to see Blainvilles with some groups even considered as residents that have chosen the deep waters outside Calheta as one of their preferred hotspots around the island.
By Paula Thake
Sightings of the day
14:30 Blainville’s beaked whales, Loggerhead turtle
10:00 Bottlenose dolphins