BIOACOUSTICS AND BEHAVIOR
The franciscana is an animal with discreet habits, being difficult to observe in nature. Therefore, much of its behavior is still a mystery to researchers. They don’t usually jump and follow boats, like other dolphin species. In general, franciscanas only show a small part of the head, back and dorsal fin when they rise briefly to the surface to breathe. Most of the time, it is the rostrum that is seen first. However, aerial images have shown that they are very agile in the water, with constant head movements.
Franciscanas are social animals that live in small family groups, with 2 to 5 individuals. It is common to find several groups in the same area while feeding. During the reproductive period, they form monogamous couples.
The sounds produced by franciscanas are very special: they emit ultrasonic clicks (high-frequency pulsed sounds) that are very different from other dolphins. These clicks cannot be heard by humans, but, once recorded, they allow researchers to recognize the species by sound alone due to its distinct pattern. In addition to clicks, franciscanas also have the ability to produce tonal sounds, or whistles, but they are rarely registered.
The sounds are produced by the movement of air in the air sacs and are emitted by the frontal region of the head, known as the melon. In the case of clicks, they bounce off obstacles in the environment and bounce back in the form of echoes, which are then captured by the animal’s jaw and transmitted to the inner ear. From this information, the franciscana is able to produce an acoustic image of the environment around it, similar to an ultrasound exam. Through this process, called echolocation, dolphins are able to find prey and navigate in the ocean.