September, like August, was an excellent month for the diversity of cetacean species observed (13 in total), but also because the sei whale (Balaenoptera borealis) maintained first place in the top 5 with a still very high percentage of observation, 86 % per day at sea.
This summer the strong presence of sei whales deserves to be noted, both in terms of the quantity and also the quality of the observations with behaviors rarely observed in the Azores. Indeed, the young individuals accompanying their mother were very curious about the boats, even forgetting about the usual “safety distance”.
We have also been able to observe these animals in very calm and supposedly resting behaviour under the surface moving at reduced speed, or in a total feeding frenzy with other species such as spotted dolphins, various species of tuna and seabirds. However, although still seen in September, the frequency of this type of sighting is clearly starting to drop.
In second place also comes the most playful specie of the summer, the Atlantic spotted dolphin (Stenella frontalis), with a percentage per day which has however clearly decreased, reaching just the 60%.
Indeed this species is mainly observed between mid-June until early October in the Azores, where it will join temporary mixed-species feeding aggregations with tuna, seabirds, common dolphins, bottlenose dolphins and sometimes other cetaceans as the sei whales as mentioned before.
The bottlenose dolphin (Tursiops truncatus), even with a slightly lower percentage of sightings than the previous month (67% in August compared to 55% in September), climbed to third place in the ranking. The bottlenose dolphin is the quintessential dolphin and one of the best-known cetaceans. Frequently observed with other species of cetaceans, some interaction can be playful and other can be more aggressive.
The common dolphin (Delphinus delphis) with its unique criss-cross or hourglass color pattern on the sides make it easy do distinguish them from most other dolphins. In September they are rising on the classification, passing from the 7th place to the 4th place. In fact, other summer species are decreasing in the area, such as the Atlantic spotted dolphins who are starting to be less encountered, and the sighting of common dolphins is increasing. We welcome back this enthusiastic and energetic bow- and wave-rider!
The sperm whale (Physeter macrocephalus) ranks 5th, with a good 50% sighting per day at sea. This flagship species was more discreet during the month of September, as were the Rissos dolphins and the pilot whales, all of which are big consumers of cephalopods.
Finally, we had some single sightings such as false killer whales, striped dolphins, beaked whales, bryde’s whale and a pygmy sperm whale.
The month of September was globally rich in species of cetaceans observed with a special mention for the always consequent presence of sei whales!