04.05.2018 – Male or female?

Occasionally our guests ask us during sightings whether the animals that we are observing are male or female. To be honest, it’s not always so easy to determine. While Pilot whales (Globicephala macrorhynchus) and Sperm whales (Physeter macrocephalus) display sexual dimorphism with male animals being evidently larger than females, dolphin sex cannot be distinguished in its phenotype from the boat. The presence of mammary slits near the stomach of the animal is an indication that the animal is female but this of course cannot be determined during a tour on a moving boat. One way of assessing the possible gender of the animal is by observing their behavior, or estimating the group size while considering the presence of calves.

There were two calves present in the small group of Bottlenose dolphins (Tursiops truncatus) we encountered on todays afternoon trip, which allowed us to assume that the group may have predominantly consisted of females. While these are merely speculations and not the ultimate truth, it’s a refreshing experience to search for clues to answer challenging questions during field observations. We watched the animals hunt and feed and, after they briefly approached our vessel, gradually returned to the marina.

By Paula Thake

Sightings of the day

Ribeira Brava

15:00 Bottlenose dolphins, Loggerhead turtle