How dolphins communicate: long‑term Sarasota study finds shared non‑signature whistles

Researchers in Sarasota recorded signature whistles and identified at least 20 shared non‑signature whistle types used by multiple dolphins, with playback tests and observations linking some types to retreat or surprise behaviors.

Researchers studying a resident bottlenose dolphin community near Sarasota, Florida report new findings on dolphin vocal behavior from a long‑running project that began in 1970. The team records animals during brief catch‑and‑release health assessments using suction‑cup hydrophones placed on each dolphin's melon and compiles the recordings in a centralized whistle database. Earlier work established that many dolphins produce stable, individually distinctive "signature whistles" that function like names. The recent analyses document shared non‑signature whistle types produced by multiple animals and explore how social relationships and context affect whistle use. Key facts: - The Sarasota Dolphin Research Program began in 1970 and follows a resident community of free‑ranging bottlenose dolphins near Sarasota, Florida. - Researchers report knowing the age, sex and maternal relatedness for almost all of the approximately 170 dolphins in the community. - Recordings are made by attaching suction‑cup hydrophones to dolphins during brief health assessments and by observing known free‑swimming individuals. - The Sarasota Dolphin Whistle Database contains nearly 1,000 recording sessions of 324 individual dolphins, and more than half of those animals have been recorded more than once. - In catch‑and‑release contexts about 85% of whistles produced are signature whistles, which are generally stable over an animal’s lifetime, especially in females. - The team has identified at least 20 shared non‑signature whistle types; playback experiments and drone‑filmed responses indicate some types may prompt dolphins to swim away while others appear when dolphins encounter unexpected sounds. Summary: The work reinforces that dolphin vocal communication includes both individual signature whistles and shared non‑signature types whose use varies with social ties and context. Researchers plan more playback experiments, expanded cataloging, and drone observation, and they are exploring artificial intelligence methods to help classify whistle types. These efforts are intended to clarify how different whistle types function across ages, sexes and group compositions.