19.07.2018 – A cetacean combination

Eventful is definitely a word to sum up our tours today. The team on our snorkeling tour were successful in their search for Atlantic spotted dolphins (Stenella frontalis) and even had the pleasure to encounter Bottlenose dolphins (Tursiops truncatus) and enjoyed a rare sighting with Risso’s dolphins (Grampus griseus). Short-beaked common dolphins (Delphinus delphis), Bottlenose dolphins, Striped dolphins (Stenella coeruleoalba) and Short-finned pilot whales (Globicephala macrorhynchus) were seen in the course of our afternoon tours on both the Stenella and our traditional boat.

Of course these animals were not all seen on one trip and not all at the same time but sightings involving aggregations of more than one species are not a rarity. Interspecific associations are in fact quite common amongst cetaceans and such interactions are especially exciting to observe.

We managed to enjoy such an event today thanks to the excellent guidance of our spotter. During the evening tour on our zodiac we encountered a herd of Short-finned pilot whales who were in the company of a handful of Bottlenose dolphins about 5 nautical miles off the coast of Jardim do Mar. This combination of species is sighted quite frequently despite the significant differences between the social lives of these two members of the toothed whale family. The reasons for such associations may vary from collaborative foraging to socializing out of pure interest and curiosity.

It may even be possible that the animals recognize one another. This is merely a personal assumption but if we consider the intelligence of these animals anddata from local research, such aquaintances aren’t impossible. Biologists in Madeira have created photo-ID catalogues based on dorsal fin features for individuals of both species to monitor the dynamics of community structures around the island. These studies suggest that the Bottlenose communities around Madeira are very fluid in structure with several partially resident offshore type individuals forming loosely structured pods into which oceanic type individuals are randomly recruited. ID catalogues for pilot whale herds, which generally have a very established social structure, have shown that different clans have displayed site fidelity to the area. This means that these animals often return to Madeira and know the waters (and probably the Bottlenose dolphin communities) around the archipelago quite well.

Whale-watching companies such as ours supply photos to these ID-catalogues and therefore play an important role in the non-invasive monitoring of cetaceans in the oceans. So, besides taking photos for our guests to show off at home in our blog we also use such pictures to help support the research and conservation of these magnificent animals.

We are happy to contribute, after all there is still SO much we do not know!

By Paula Thake

Sightings of the day

Ribeira Brava

17:00 Short-beaked common dolphins

Stenella

09:00 Atlantic spotted dolphins (snorkeling), Bottlenose dolphins, Risso’s dolphins

15:30 Atlantic spotted dolphins, Bottlenose dolphins, Striped dolphins

18:00 Bottlenose dolphins, Short-beaked common dolphins, Short-finned pilot whales