05.11.2018 – Like old friends

Both our boats managed to reach a herd of Short-finned pilot whales (Globicephala macrorhynchus) this morning, that were travelling west alongside a few Bottlenose dolphins (Tursiops truncatus). Sightings involving mixed groups of these two cetacean species were rather frequent these last days and it would be interesting to find out whether the animals associating with one another may always be the same groups.

To further understand such sightings and the dynamics between groups of animals, our team has aimed to become more familiar with the photo-ID catalogues that have been compiled by local scientists over the years, particularly those of regularly sighted cetaceans like the ones encountered today. Dorsal fins of adult delphinids often contain several nicks that mainly occur as a result of repetitive body contact with fellow peers during socializing activities. Such nicks are reliable long-term markings that enable scientists to identify individual animals and thereby understand the group dynamics of the populations around Madeira.

Local research has shown that the Short-finned pilot whales frequenting the island occur in rather fixed group constitutions, with four of the visiting clans displaying residential patterns. Such information is extremely vital when it comes to identifying hotspots for the animals, which can in future be converted into marine sanctuaries.If we become more familiar with these catalogues, we can begin to understand whether these animals have just recently become aquainted with one another or whether they are greeting each other like old friends in the ocean.

Those of you who wish to discover what such a catalogue looks like should click on the link below. Here various documents crreated by the Oceanic Observatory of Madeira (OOM) can be downloaded, including a Photo-ID catalogue of the Short-finned Pilot whales around Madeira:

https://oom.arditi.pt/index.php?page=produtos

By Paula Thake

Sightings of the day

Ribeira Brava

10:00 Bottlenose dolphins, Short-finned pilot whales

Stenella

10:00 Bottlenose dolphins, Short-finned pilot whales