Study

Dialect change in resident killer whales: implications for vocal learning and cultural transmission

Deecke, Volker B.; Ford, John K. B.; Spong, Paul

Animal Behaviour, 2000

Peer-reviewedlongitudinal studywild

What they did

Archived recordings of specific resident killer whale matrilines spanning more than a decade were compared using neural-network classification of call structure, asking whether the shared calls of a group stay fixed or drift over time.

Studied in: Orcinus orca
Sample size: calls from two matrilines compared across a 12-year recording archive

What they found

Call structure changed gradually over the period, and the changes were shared within a matriline rather than occurring independently in individuals. Two related matrilines diverged from one another as they changed.

What it means

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

How the authors put it

Killer whale dialects change through cultural drift, with modifications learned and shared within the matriline — evidence of vocal learning maintaining group-specific traditions.

How NatureHQ reads it

A dialect that never changed could be explained by inheritance. One that drifts, and drifts together within a group while diverging from a related group, cannot — that is the signature of learning. It is also the mechanism by which relatedness between matrilines can be read from how similar their calls are, and how two populations sharing the same water end up acoustically distinct.

Limitations

Two matrilines from one population; recording effort varies across years.
Automated classification of call similarity involves methodological choices that affect the result.
Cultural drift is inferred from the pattern rather than observed being transmitted.