24.06.2021 – Whirlpool

Today we encountered two seasonal marine mammal species that can be found here off Madeira’s coast. We refer to our elegant Short-beaked Common dolphins (Delphinus delphis) as our winter dolphins, and the lively Atlantic spotted dolphins (Stenella frontalis) mainly stay here in summer.

The small school of the beautiful Common dolphins was gliding relaxed through the blue sea. The quality of this encounter was inspiring and gentle.

The Atlantic spotted dolphins always seemed to send subgroups to the Ribeira Brava, which surfed there in the bow wave. A diversionary maneuver? Because the main group was completely absorbed in another activity. They seemed to be in a love frenzy. Well, as it turned out, Spotted dolphins don’t take privacy very seriously, because they sometimes made their love banter close to the boat. Often, two males hold a female in their midst, while a third male approaches the female from below. During such mating processes, the resulting activity often gushes the water like a whirlpool. And whirlpools were plentiful today.

The researcher Dara Orbach and her team found that female dolphins may be able to determine the paternity of their calf themselves. The researcher called this “post-copulatory paternity control”. Because the dolphins’ vagina is made up of many folds and niches, a female can direct the unwanted applicant’s penis into a niche. His sperm is now at a competitive disadvantage. While she puts herself in the right position for a desirable male.

Another behavior, dynamic leaps, we were also able to observe frequently today. Leaps are a diverse medium for non-verbal communication in dolphins, among other things they are also used to impress. Today’s leaps were phenomenal. One could well imagine that a female dolphin could easily be wrapped around her finger by such skilled and dynamic leaps.

🙂

by Fatima Kutzschbach

Sightings of the day

Ribeira Brava

10:00 Common dolphins, Atlantic spotted dolphins