27.09.2019 – Harmony
Things are usually pretty peaceful out in the ocean even if animals from different species encounter one another. Such mixed species encounters (MSE) belong to some of the most important and interesting observations for behavioural scientists studying cetaceans! Toothed whales are particularly gregarious with some species like the Bottlenose dolphins (Tursiops truncatus) being more curious and social with other species than their more timid relatives. They are most frequently seen socialising with Short-finned pilot whales (Globicephala macrorhnychus) here in Madeira with most of these associations being very harmonious in nature.
Encounters with Atlantic spotted dolphins (Stenella frontalis), however, often consist of the larger Bottlenose displaying rather aggressive behaviour toward their smaller relatives. Such aggressive behaviour was even observed amongst resident Bottlenose and Spotted in the Bahamas by the Wild Dolphin Project but was observed to be altered after populations of both species were affected by two hurricanes in 2004. While the general social structures of each species community remained relatively intact, the temporal associations amongst the two different species varied after the storms receded with a significant reduction in aggressive behaviour. Whether environmental disturbances could have similar effects on the populations of these two cetaceans here in Madeira remains to be discussed.
However the most peaceful MSE of the day took place between snorkelers and spotted dolphins during this mornings tour. Our guests behaved perfectly in the water and our crew, as always, respected the behaviour displayed by the enormous group of dolphins that our spotter managed to track down. While we don’t have the power to determine the quality of such a sighting entirely through our own respectful behaviour, it does make a visible difference! So well done and thank you to all participants this morning, this was another one for the books!
By Paula Thake
Sightings of the day
13:30 Atlantic spotted dolphins, Loggerhead turtle
09:00 Atlantic spotted dolphins (Snorkeling)
12:00 Atlantic spotted dolphins
15:30 Atlantic spotted dolphins, Bottlenose dolphins, Short-finned pilot whales