03.08.2021 – Guessing game

As experienced as our team is when it comes to identifying cetaceans at sea, these smart creatures do occasionally have us scratching our heads when guests ask us about the species. Since the animals are often only partially visible at the surface, our team resorts to checking physical characteristics such as the dorsal fin or spout (in the case of a large whale) and even looks out for behavioural patterns or group dynamics that may be characteristic for a certain species. Nonetheless, sometimes these animals simply leave us guessing.

Our spotter had already spotted the large whale feeding in the company of a group of dolphins this morning. As we entered the sightings area, we immediately recognised the curious and energetic behaviour typical of the Atlantic spotted dolphins (Stenella frontalis) and a few of them confirmed our assumptions as they curiously approached our bow, before continuing their hun for Atlantic mackerel (Scomber scombrus). As we watched the dolphins dart towards the shore, an enormous baleen whale (Balaenoptera) surfaced, exposing its marked dorsal fin and the numerous cookie-cutter shark scars along its flank. Such scars may be an indication of an older animal and are most frequently seen on the larger rorquals like the Fin whale (Balaenoptera physalus). Despite its size, our team assumed the whale was a mature Sei whale (Balaenoptera borealis) or Bryde’s whale (Balenoptera edeni). In the end, after checking our photos and those from another whale-watching company on site we settled for it being a Sei whale, due to the absence of the three rostral ridges typical for Bryde’s whale. Phew! That one sure had us guessing!

In the afternoon we met yet another group of spotted dolphins and the sharp eyes of our captain Filipe even spotted a handful of Striped dolphins (Stenella coeruleoalba) camouflaged in the group. Our spotter often has trouble distinguishing the two species from land due to their surprisingly similar group dynamic. As we were returning to the marina we were greeted by a group of Short-beaked common dolphins (Delphinus delphis) close to shore. Whilst the yellow hourglass pattern on their flanks is uncanny and makes it almost impossible to confuse them with other species at sea, at a distance it can be tricky to recognise these dolphins. What a day!

By Paula Thake

Sightings of the day

Ribeira Brava

10:00 Atlantic spotted dolphins, Baleen whale

15:00 Atlantic spotted dolphins, Striped dolphins, Short-beaked common dolphins