Study

Signature whistles of free-ranging bottlenose dolphins Tursiops truncatus: stability and mother-offspring comparisons

Sayigh, Laela S.; Tyack, Peter L.; Wells, Randall S.; Scott, Michael D.

Behavioral Ecology and Sociobiology, 1990

Peer-reviewedlongitudinal studywild

What they did

Whistles were recorded from individually known wild dolphins in Sarasota Bay during temporary capture-and-release health assessments, repeated over years, allowing the same animal to be recorded at intervals and calves compared with their mothers.

Studied in: Tursiops truncatus
Sample size: individually identified wild dolphins recorded across years

What they found

Signature whistle contours remain stable over at least a decade. Calves develop distinctive whistles within the first year that generally differ from their mother’s, though some daughters produce whistles resembling hers.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

The signature whistle is developed early, is individually distinctive, and is retained essentially unchanged across a lifetime.

How NatureHQ reads it

The stability is what makes the "name" analogy tempting, and it is the part that holds up best. A label that changed every few years would be useless for identifying an individual across a long life in a fission–fusion society where animals separate and reunite constantly. That the whistle is invented rather than inherited — calves generally do not copy their mothers — is the other half.

Limitations

Recording requires temporary restraint, which is itself an unusual context.
One long-studied population that may not be typical.
Whether a whistle is truly unchanged, or merely recognisable, depends on the acoustic measure used.