Dolphins are raising their voices just to be heard

Research published in the Journal of Experimental Biology shows that noisy humans are impacting the physiology and behaviors of dolphins and whales. To compete against man-made noises, these animals are altering the amplitude, frequency or length of their vocalizations or repeat what they need to say with the hope of being heard. Dr. Maria Holt and colleagues studied a par of bottlenose dophins vocalizing and discovered that the oxygen intake of the animals increased as they raised their voices. The team then calculated the number of additional calories the dolphins would need to ingest to make up for the extra energy used to communicate in a noisy environment. The results of these calculations showed that two additional calories were needed to make up for every two minutes the animals spent communicating over noises. According to a quote from Dr. Holt published in Scientific American: “To survive and breed, you have to make sure you have enough calories every day to support those activities.” Therefore, animals that live in a noisy environment which may have limited food availability might have a more difficult time supporting their metabolic needs. For juvenile or nursing dolphins, that already require additional nutrition, the costs may be more detrimental to the health of the animals.

Sources:

Holt MM, Noren D, Dunkin RC, Williams TM. Vocal performance affects metabolic rate in dolphins: implications for animals communicating in noisy environments. Journal of Experimental Biology. 218: 1647-1654, 2015.

Scientific American