31.08.2018 – Dolphin co-occurrences

Today we found an interesting situation out on the ocean: there were Short-beaked common dolphins (Delphinus delphis) closely accompanied by Short-finned pilot whales (Globicephala macrorhynchus). Occasionally, we find different combinations of cetacean species hanging out in close vicinity to each other but Common dolphins and Pilot whales, that is a rare combination.

There are a few potential reasons for co-occurrences among cetacean species. They could be looking for the same type of prey species and therefore hunt together. They might also share their travelling direction. Swimming alongside animals of another specie might increase the level of security but even direct social interactions can be an underlying cause.

It is very hard to tell what might have been the reason for the two mentioned species swimming close together today. Anyway, the situation didn’t last very long as the Common dolphins moved off and speeded up for hunting.

Another highlight of the day have been two very interactive female Blainville´s beaked-whales (Mesoplodon densirostris) approaching the Ribeira Brava closely and staying around for a good while.

by Jan-Christopher Fischer

Sightings of the day

Ribeira Brava

10:00 Blainville beaked whales, Short-finned pilot whales, Short-beaked common dolphins

15:00 no sightings

Stenella

08:30(Snorkeling) Short-beaked common dolphins, Short-finned pilot whales

12:00 Short-finned pilot whales, Striped dolphins, Bottlenose dolphins

18:00 Short-beaked common dolphins, Atlantic spotted dolphins