Each bottlenose dolphin has its own distinct high-pitched whistle. Marine mammals use these whistles for identification, communication and bonding. They can even imitate the whistles of close friends and family.
“A signature whistle is often said to be similar to a name because it is individually distinct and serves to identify the animal,” National Marine Mammal Foundation researcher Brittany Jones told NBC News’ Sarah Sloat.
Previous research has shown that pods of dolphins tend to develop different whistling styles, but why dolphins develop these styles is still unclear, a statement said.
In a new study published in Scientific reports, scientists have found that the location and population demographics of bottlenose dolphins, genus Tursiopsinfluence the differences in these signature whistles even more than genetics.
The researchers collected 188 hours of recorded acoustic data on common bottlenose dolphins in the Mediterranean Sea and analyzed the differences in whistles between six distinct populations. They found that, like regional accents in humans, dolphins had similarities in their signature whistle depending on where they lived.
For example, dolphins living in seagrass areas had higher pitched and shorter signature whistles than dolphins in areas with muddy seabed, the statement said. The article explains why this happens: “Sound transmission in shallow waters is highly variable and depends on bottom sediments…temperature gradients, freshwater inputs, obstacles in the sound path and the interactive effect between sediments and plants (such as seagrasses) and/or animals (such as benthic fauna) that live on the bottom.
Population size also had an effect on whistle development – small populations had more pitch changes in their whistles than large populations. Together, the article concludes that the environmental conditions and demographics of a dolphin pod contribute strongly to signature whistles.
Other studies have looked at the development of whistles in specific subpopulations, such as bottlenose dolphins in the waters around Florida, Portugal and Namibia, but this study is a first for its breadth and scope in the study area, with a larger study area than any previous search. .
“The study provides the first evidence that the genetic structure, which distinguishes eastern and western Mediterranean bottlenose dolphin populations, does not have a strong influence on the acoustic structure of their characteristic whistles, and that the geographic isolation between populations only partially affects whistle variability”. according to the authors.
The study indicates that ambient noise and vessel traffic data were not available for all sites, so these factors could not be included in the research. However, previous studies have shown that high ship noise levels “can have a strong influence on whistle structure,” the authors write, although noise alone is not enough to explain differences in whistles.
“I would like people to think about the importance of the acoustic environment that dolphins live in for the development and maintenance of their communication,” lead study author Gabriella La told Earth.com. Manna, marine biologist at the University of Sassari in Italy. Andrei Ionescu. “Human activities, such as commercial shipping and nautical traffic, can seriously affect this fundamental aspect of dolphin life. ”
Another recent study showed that bottlenose dolphins can also be recognized by the taste of their urine.